Network Working Group Yunqing.Zeng Internet Engineering Task Force MCM INTERNET-DRAFT 19 September 2002 Expires March 2003 Enhanced Internet Protocol Specification Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026 except that the right to produce derivative works is not granted. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a Maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." Distribution of this memo is unlimited. The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Abstract This document describes aspects of "multi-tier" architecture, "Grid-net", addressing architecture, "address plane", "address swapping", "address option", and revises aspects of the security, precedence of the Standard Internet Protocol to suit newly development trend of Internet, Municipal Area Network, and "Home-net". This new addressing architecture provides much more capacious address space by attached 32-bit "Grid" IP address for transmitting datagram from sources to destinations, where hosts identified by twin 32-bit IP addresses, i.e. to provide "non- private" 32-bit IP address for transmission in adding "Grid" tier, and scalable service for data, voice, signaling, and multimedia. The proposed protocol provides of seamless integration with existing Internet, tier Boundary address swapping for transmission throughout public Internet tier, IP address planes inside Grid-net for data, IP phone, mobile phone, wireless PAD, video and other multimedia applications, and IP address personality for personal computer, IP phone, mobile phone, wireless PAD, home control/monitoring, and multimedia equipments. The goal of this document is to discusses the semantics of Enhanced Internet protocol for improvements, to provide a compatible mechanisms for less influence on most existing network equipments, to create new Internet Multimedia Environment, and to protect worldwide investment on network resources. Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. Expires March 2003 [Page 1] Draft Revised Internet Protocol September 2002 Table of Contents 1. INTRODUCTION ------------------------------------------- 4 1.1. Motivation ------------------------------------------- 4 1.2. Scope ------------------------------------------- 4 1.3. Network Architecture ------------------------------------ 4 1.4. Addressing Architecture --------------------------------- 6 1.5. Operation ------------------------------------------- 8 2. OVERVIEW ------------------------------------------- 8 2.1. Relation to Other Protocols ----------------------------- 8 2.2. Model of Operation -------------------------------------- 9 2.3. Enhanced Function Description --------------------------- 10 2.3.1. Names and Addressing ------------------------------------ 10 2.3.2. Fragmentation ------------------------------------------- 12 2.4. Gateways ---------------------------------------- 14 3. SPECIFICATION --------------------------------------- 14 3.1. Enhanced Internet Header Format ------------------------- 14 3.1.1. Version: 4 bits --------------------------------------- 16 3.1.2. IHL: 4 bits ------------------------------------------- 16 3.1.3. Type of Service: 8 bit ---------------------------------- 16 3.1.4. Total Length: 16 bits ---------------------------------- 17 3.1.5. Identification: 16 bits -------------------------------- 17 3.1.6. Flags: 3 bits ------------------------------------------ 17 3.1.7. Fragment Offset: 13 bits ------------------------------ 17 3.1.8. Time to Live: 8 bits ----------------------------------- 17 3.1.9. Protocol: 8 bits --------------------------------------- 18 3.1.10. Header Checksum: 16 bits ------------------------------ 18 3.1.11. AAO Header: 8 bits ------------------------------------ 18 3.1.12. AAO Length: 8 bits ------------------------------------ 19 3.1.13. Flow Labels: 16 bits ---------------------------------- 19 3.1.14. Attached Source Address ------------------------------- 19 3.1.15. Attached Destination Address -------------------------- 19 3.1.16. Options: variable ------------------------------------ 19 3.1.17. Padding: variable ------------------------------------- 20 3.2. Specific Option Definitions ------------------------------ 20 3.2.1. End of Option List ------------------------------------- 20 3.2.2. No Operation ------------------------------------------- 21 3.2.3. Security ----------------------------------------------- 22 3.2.4. Loose Source and Record Route -------------------------- 23 3.2.5. Strict Source and Record Route ------------------------- 23 3.2.6. Record Route ------------------------------------------- 24 3.2.7. Stream Identifier ---------------------------------------25 3.2.8. Enhanced Internet Timestamp -----------------------------25 3.3. Discussion --------------------------------------------- 26 3.3.1. Addressing --------------------------------------------- 26 3.3.2. Example Address Swapping ------------------------------- 27 3.3.3. Compatibility ------------------------------------------ 28 3.3.4. Fragmentation and Reassembly --------------------------- 28 3.3.5. Example Fragmentation Procedure ------------------------ 29 Expires March 2003 [Page 2] Draft Revised Internet Protocol September 2002 3.3.6. Example Reassembly Procedure ---------------------------- 30 3.3.7. Identification ---------------------------------------- 31 3.3.8. Type of Service ---------------------------------------- 32 3.3.9. Time to Live ---------------------------------------- 32 3.3.10. Options ---------------------------------------- 33 3.3.11. Checksum -------------------------------------------- 33 3.3.12. Errors ---------------------------------------------- 33 3.4. Interfaces --------------------------------------------- 33 3.4.1. An Example Upper Level Interface ---------------------- 34 4. APPENDIX ----------------------------------------------35 4.1. APPENDIX A: Examples & Scenarios -----------------------35 4.1.1. Example 1: --------------------------------------------35 4.1.2. Example 2: ------------------------------------------36 4.1.3. Example 3: ------------------------------------------37 4.2. APPENDIX B: Data Transmission Order ------------------- 37 5. GLOSSARY ----------------------------------------------38 6. REFERENCES -------------------------------------------------39 7. Authors' Addresses ------------------------------------------40 Expires March 2003 [Page 3] Draft Revised Internet Protocol September 2002 Enhanced Internet Protocol Specification 1. INTRODUCTION 1.1. Motivation The Internet Protocol is designed for use in interconnected systems of packet-switched computer communication networks. Predictions of IPv4 32-bit IP address crisis date back to the early 1990s, but global transition to the more capacious 128-bit IP Version 6 protocol, so-call Next Generation Internet program protocol, has not begun, and found out the hard way. Shift to a new protocol will affect 90 million routers, switches, computers, and excessive growth in the routing tables. The proposed Enhanced Internet protocol IPv4.e provides much more capacious address space by attached 32-bit "GRID" IP address for transmitting blocks of data called datagram from sources to destinations, where sources and destinations are hosts identified by normal 32-bit IP addresses when transmitted in existing Internet tier, or identified by enhanced twin 32-bit IP addresses, i.e. to use 2'nd tier 32-bit IP address for transmission in adding "GRID" tier. The proposed Enhanced internet protocol provides of seamless integration with existing Internet, and scalable service for data, voice, signaling, multimedia in adding tier, and provides more flexibility for security, precedence, compartments, fragmentation and reassembly of long datagram, and handling restriction features of the Standard Internet Protocol. The goal of the Enhanced internet protocol is to provides flexible Addressing Architecture, millions times more capacious address space to overcome address crisis that Ipv4 will faced, and to implement an perspicuous, compatible protocol to create new Internet Multimedia Environment, which would be coexistent with existing world wide Internet. The Enhanced internet protocol has more specification, such as IP address planes for data, IP phone, mobile, wireless PAD, video and multimedia application, and IP address personality for personal computer, IP phone, mobile, wireless PAD, home control, monitoring, and multimedia equipments. It's never too late to mend; it would protect worldwide investment on network resources. 1.2. Scope The Standard internet protocol is specifically enhanced in scope to provide more address space, flexible addressing architecture, and still capitalize on the functions, mostly provided by original network equipments, necessary to deliver a package of bits (an internet datagram) from a source to a destination over an tiered interconnected networks. There are more mechanisms to augment end-to-end data reliability, flow control, sequencing, or other services commonly found in its supporting networks to provide various types and qualities of service. 1.3. Network Architecture The core design principles and technology for large, decentralized, open-access networks, such as the Enhanced Internet, is commonly tiered into a hierarchical architecture. This protocol describes a new way to Expires March 2003 [Page 4] Draft Revised Internet Protocol September 2002 organize Internet network in three tiers, that differs from conventional two tier architectures, by adding a new "Grid-net" tier between Internet and Intranet. For example, a "Grid-net" could be a Municipal Area Network, to provide service for millions of small or middle scale Enterprise's Intranet and "Home-net", where personal computer, video-player, consumer electronic, building automation and wireless appliance are link to the "Grid-net" by gataways or "Home-net" bridge. A "Grid-net" also could be a Campus Network, or a large Enterprise's Network. The main contribution of this protocol is to describe the ideas behind our new architecture, illustrate the advantages of using the conceptual architecture, and demonstrate that this architecture results in capacious Enhanced Internet Address by less effect on current running Internet environment and huge investment in network construction. This protocol is called on by host-to-host protocols in a tiered Internet environment, and calls on local network protocols to carry the Internet datagram to the next gateway or destination host. Hierarchy of Enhanced Internet is as following: +-------------------------------------------------------------------+ |---------------------- Internet Tier ------------------------------| +---+-------+------+--------+---------+-------+---------+-------+---+ | PE | | PE | | PE | ... | PE | +-------+ +--------+ +-------+ +-------+ | | | | +-------+ +--------+ +-------+ HOST | GE | | GE | | CE | +-------+------+--------+ +---+--------+---+ | Grid-net Tier | | Intranet Tier | +-------+------+--------+ +----------------+ | PE | | PE | | +-------+ +--------+ HOST | | +-------+ +--------+ | CE | | CE | +---+-------+---+ +-+--------+-+ | Intranet Tier | | Home-net | +---------------+ +------------+ | HOST Enhanced Internet Hierarchy Figure 1. Here, PE is Provider End gateway, GE is Grid End gateway and CE is Customer End gateway. For example, a TCP module, which is situated in a host of a Grid-net, would call on the Internet module to take a TCP segment (including the TCP header and user data) as the data portion of an Internet datagram. The suggested TCP module would provide the tiered IP addresses and other parameters in the TCP header to the Internet module as arguments of the call. Expires March 2003 [Page 5] Draft Revised Internet Protocol September 2002 The Internet module would then create an Internet datagram and call on the local network interface to transmit the Internet datagram. If the Internet datagram would be transmitted to the other Grid-net in the Internet, there should be an Internet IP address in the destination portion of the TCP header, and attached second Grid-net IP address in the option field of the TCP header. The Internet datagram would be transmitted across the first "GRID" border to the Internet destination, the source Grid-net IP address would be swapped by the "GRID" Boundary gateway, i.e. replaced by Internet IP address of the "GRID". The Internet destination host might be a Boundary gateway to the second GRID. The Internet module on the second "GRID" Boundary would then swap the destination IP address in the TCP header of the Internet datagram, and then call on the neighboring network interface to transmit the Internet datagram to the Grid-net destination. The Grid-net address would be derived from the attached Grid-net destination IP address option by the second "GRID" Boundary gateway, and would be the address of some host in that Grid-net. 1.4. Addressing Architecture The Enhanced Internet protocol implements three basic functions: addressing, address swapping and fragmentation. The Internet modules use the addresses carried in the Enhanced Internet header to transmit Internet datagram toward their tier's destinations node or their tier's edge, in between the Internet modules in the "GRID" Boundary gateway use the addresses carried in attached address option fields of the Enhanced Internet header to replace the source or destination address field, then to transmit Internet datagram toward their next tier's destination node. Firstly, there is no change for the Addressing Architecture in Internet tier, for the Grid-net itself Addressing in Internet, a C class network address may be used, which has 8-bits address space, and splits up to some Address segment, which we name as "Address Plane": Data Plane, Control Plane, Voice Plane, Signaling Plane, Video Plane, Wireless Plane, and some other multimedia and reserved Address space. That forms the vertical Addressing Architecture. It would be effective and efficient to uniquely define Address Plane and to separate their paths and processing for different Service Provider. The "GRID" Boundary gateway using relative plane's address should have those corresponding functions, and support from relative Service Provider. For example, Signaling Plane could link to Signaling gateways provided by local PSTN operator, and Wireless Plane could link to Wireless gateways provided by local GSM or CDMA operator. There could be several corresponsive "Network Plane" physically in "GRID" local network, which can use same "GRID" tier interior address, but in different plane. For the Grid-net interior addressing, each Grid-net Addressing Plane has a reserved but now "non-private" "A" class network address. We suggest to use reserved address number (10.x.x.x / 28) for Data Plane, let the last 4-bits for Client Data Plane Addressing, and which splits at most up to 16 personality network address. By little trim, the reserved address number (10.x.x.x / 28) may also be used for Wireless Plane, Video Plane, and so on. For personality, same address number in different plane may assign to same one personnel. Even non-reserved Expires March 2003 [Page 6] Draft Revised Internet Protocol September 2002 address number (2o.x.x.x / 28) or (30.x.x.x / 28) may used for plane address, and assign to same one person for physically interconnected address planes. By plane address swapping, which we name for "In-tier Address Swapping", a datagram can be transmitted to other plane. Roughly estimated, the Grid-net Addressing Architecture totally supports up to one million clients, and client could possess all services currently from different local Service Provider in digital mode. The Enhanced Internet protocol increases the IP address size from 32 bits to 64 bits, (or even up to 96 bits if needed in future), to coexist in a more levels of addressing hierarchy, a much greater number of addressable nodes, and simpler auto-configuration of addresses for " Grid-net" and "Home-net" client. The Enhanced Internet protocol supports more services in several address "Plane", and the scalability of multicast routing is improved by adding the address "Plane" field, which we name for "Plane multicast " to all personal digital appliances. Enhanced Ipv4 header uses 32 bits address fields for tier transmission, to reduce the processing cost of packet handling, to limit the bandwidth cost of the Internet Backbone, and to protect worldwide investment on Internet Backbone and other network appliances. 1.5. Operation The selection of a path for transmission is called routing, including Internet tier routing and Grid-net tier interior routing. The Internet modules would process routing as used be, and be allowed to use different route protocol in tier mode The Internet modules may use fields in the Enhanced Internet header to fragment and reassemble Internet datagram when necessary for transmission throughout Grid-net. The model of operation is that two Internet module, which reside in each host and if both are situated in the Internet tier, would be engaged in Internet communication as model of original Internet protocol. These modules share common rules for interpreting address fields and for fragmenting and assembling enhanced Internet datagram. In addition, those modules, which both reside in one Grid-net tier, would be engaged in GRID communication same as model of original Internet protocol. But especially for Internet communication across GRID Boundary, these modules, which reside in each host, have procedures for attaching next tier's IP address (Internet or Grid-net 32-bit address) of the host, for routing decisions and other functions. The Internet modules, which reside in GRID Boundary gateway, have procedures for IP address swapping between Internet and Grid-net 32-bit address (use the addresses carried in option fields of the Enhanced Internet header), and for routing decisions in next tier. It is clear, that the standard sequent procedure from a client in the Grid-net tier, to a Proxy, and to a server in the Internet, is still effective. The Enhanced Internet protocol treats each Internet datagram as an independent entity unrelated to any other Internet datagram. There are no connections or logical circuits (virtual or otherwise). The Enhanced Internet protocol uses five key mechanisms in providing its service: Address Swapping, Type of Service, Time to Live, Options, and Header Checksum. The Address Swapping is an abstract, which characterize the network Expires March 2003 [Page 7] Draft Revised Internet Protocol September 2002 tier choices and their actual unique 32-bit IP address in that network tier. Source and destination IP address in the Internet header are set by the sender of the datagram, and represented as 32-bit address for transmission in tier mode, and combined with attached source and destination IP address option in the Internet header, would be specifically represented as 64-bit address for those host in Grid-net tier, (i.e. Internet IP address :: Grid-net IP address). This type of address indication is used merely by Grid-net tier Boundary gateways to select the adequate unique 32-bit IP address for datagram transmitting in next tier, either the internet tier or the Grid-net tier for the next hop, or for the next Boundary gateway when routing an Internet datagram to the other "GRID" networks. The Type of Service is used to indicate the quality of the service desired. The type of service is an abstract or generalized set of parameters, which characterize the service choices provided in the networks that make up the Internet. This type of service indication is to be used by gateways to select the actual transmission parameters for a particular sub-network for the next hop. The Time to Live is an indication of an upper bound on the lifetime of an Internet datagram. It is set by the sender of the datagram and reduced at the points along the route where it is processed. If the time to live reaches zero before the Internet datagram reaches its destination, the Internet datagram is destroyed. The time to live can be thought of as a self-destruct time limit. The Options provide for control functions used in some situations, but unnecessary for the most common communications. The options include provisions for attached address, timestamps, security, and special routing. The Header Checksum provides a verification that the information used in processing Internet datagram has been transmitted correctly. The data may contain errors. If the header checksum fails, the Internet datagram is discarded at once by the entity, which detects the error. The Enhanced Internet protocol could provide a reliable communication facility and flow control, and also implemented in tier Boundary gateways during Address Swapping interval. There are no acknowledgments either end-to-end or hop-by-hop. There is no error control for data, only a header checksum. There are no retransmissions. Errors detected may be reported via the Internet Control Message Protocol (ICMP), which is implemented in all Internet protocol module, including those tier Boundary gateways. 2. OVERVIEW 2.1. Relation to Other Protocols Internet protocol interfaces on one side to the higher-level host-to-host protocols and on the other side to the local network protocol. In this context a "local network" may be a small network in an office building, at a home, or in a large network such as the network over a district. The following diagram illustrates the place of the Enhanced Internet protocol in the protocol hierarchy: Expires March 2003 [Page 8] Draft Revised Internet Protocol September 2002 +-------------------------------------------------+ Application |Telnet | FTP | TFTP| Mobile |Voice | Video| ... | +-------------------------------------------------+ Transport | TCP | UDP | ... ... | +-------------------------------------------------+ Network, Gateway | Enhanced internet Protocol & ICMP | +-------------------------------------------------+ Link | Local Network Protocol | +-------------------------------------------------+ Protocol Relationships Figure 2. 2.2. Model of Operation The following scenario illustrates the model of operation for transmitting a datagram from one application program to another. We suppose that this transmission will involve some intermediate gateways. The sending application program prepares its data and calls on its local internet module to send that data as a datagram and passes the destination address, which is an internet tier address for out-bound, or a GRID tier address for in-bound, and attached destination address if needed, which is another GRID address for out-bound, and other parameters as arguments of the call. The Internet module prepares a datagram header and attaches the data to it. When the Internet module determines a Grid-net destination address for this datagram, which is the address of an inner gateway. It sends this datagram to the local network interface. The local network interface creates a GRID local network header, and attaches the datagram to it, then sends the result via the GRID local network. The datagram arrives at a gateway host wrapped in the GRID local network header; the local network interface strips off this header, and turns the datagram over to the Internet module. The Internet module determines from the GRID destination address that the datagram is to be forwarded to another host in this GRID local network. The Internet module calls on the local network interface for that network to send the datagram. This local network interface creates a local network header and attaches the datagram sending the result to the destination host. At this destination host the datagram is stripped of the GRID local net header by the local network interface and handed to the Internet module. The Internet module determines that the datagram is for an application program in this host. It passes the data to the application program in response to a system call, passing the source address and other parameters as results of the call. Application Application Program Program \ Inner gateway / Internet Module Internet Module Internet Module \ / \ / LNI-1 LNI-1 LNI-2 LNI-2 \ / \ / GRID Local Network 1 GRID Local Network 2 Transmission Path in Gridnet Figure 3 Expires March 2003 [Page 9] Draft Revised Internet Protocol September 2002 When the Internet module determines an Internet tier network address for the destination address, in this case it is the address of an Internet host. It sends this datagram to the GRID Boundary gateway. The local network interface creates a local network header, and attaches the datagram to it, then sends the result via the GRID local network to the GRID Boundary gateway. The datagram arrives at a GRID Boundary gateway wrapped in the local network header; the GRID Boundary gateway interface strips off this header, and turns the datagram over to the Internet module. The Internet module determines from the Internet IP address that the datagram is to be forwarded to some host in Internet. The Internet module determines an Internet IP address for the destination host. It calls on the local network interface of the GRID Boundary gateways for that network to send the datagram. This GRID Boundary gateways creates a Internet network header, which attaches the source host GRID' Internet address, and attached source host GRID address, and datagram, sending the result to the destination host in Internet. At this destination host the datagram is stripped of the network header by the local network interface and handed to the Internet module. The Internet module determines that the datagram is for an application program in this host. It passes the data to the application program in response to a system call, passing the source internet IP address, and attached source GRID IP address, and other parameters as results of the call. Application Program in Internet tier . / . Internet Module . / . LNI-3 . / Application GRID Boundary gateway Program in GRID tier Swap Address \ Inner gateway / Internet Module Internet Module Internet Module \ / \ / LNI-1 LNI-1 LNI-2 LNI-2 \ / \ / GRID Local Network 1 GRID Local Network 2 Transmission Path traversing a Grid-net to Internet Figure 4 By the way, if it is impossible to process GRID IP address by the application program in destination Internet host, alternatively source host could send this datagram and the GRID local network address to the GRID proxy. 2.3. Enhanced Function Description The function or purpose of Enhanced Internet Protocol is to move datagram through a tiered interconnected set of networks. This is done by passing the datagram from one Internet module to another until the destination is reached. The Internet modules reside in hosts and gateways in different network tier or on the tier Boundary. Expires March 2003 [Page 10] Draft Revised Internet Protocol September 2002 The datagram are routed from one Internet module to another through individual networks or GRID tier Boundary, which are based on the interpretation of an Enhanced Internet address. Thus, one important mechanism of the Enhanced Internet protocol is the network addressing. In the routing of messages from one Internet module to another, datagram may need to traverse a network or a network tier, whose maximum packet size is smaller than the size of the datagram. To overcome this difficulty, a fragmentation mechanism is provided in the Enhanced Internet protocol as usually. 2.3.1. Names and Addressing A distinction is made between names, addresses, and routes [4]. A name indicates what we seek. An address indicates where it is. A route indicates how to get there. The Enhanced Internet protocol deals primarily with tier IP addresses. It is the task of higher level (i.e., host-to-host or application) protocols to make the mapping from names to addresses. Name system should have unique and efficient structure correspond with Address tier's architecture. Due to extremely large GRID IP address space, many names could be mapped to one Internet Network address. So it is helpful to have a tree structure for Names. Name consists of several portion, is separated by comma, and is arranged in sequence: For example from left to right: , , , and . Each GRID has its unique domain name suffix attached to the target names. The DNS in Internet tier maps GRID domain name suffix to GRID Boundary gateways addresses. The uniform Domain Name policy has to be adopted by the GRID DNS for Assigned Names and Numbers, and the administrative resolution service provide rules. For example, a GRID in Shenzhen of China has a GRID domain name suffix as ".sz.cn", so a person has his home-Web name as "xxxxxx.hom.sz.cn" for his house real-time information browsing and control, and has his personal SGM mobile-phone name as "xxxxxx.gsm.sz.cn", and "xxxxxx@sms.gsm.sz.cn"to receive short message from whatever node in the world by near future. There are two cases for the representation of an address: Case 1: A single address of four octets (32 bits), and represented as ( I. I. I. I ). Case 2: Two single address of four octets (total 64 bits), which consists of Internet address (32 bits) and Grid-net address (32 bits), and represented as ( I. I. I. I :: G. G. G. G). All 32 bits addresses begin with a network number, followed by area address (called the "rest" field). The example of the mapping from names to addresses is as following: Name Address Address Plane ------- ---------- ---- "someone.hom.sz.cn" 204.16.16.0::10.35.78.96 data "someone.gsm.sz.cn" 204.16.16.192::10.35.78.96 mobile There are three formats or classes of Enhanced internet addresses: in class A, the high order bit is zero, the next 7 bits are the network, and the last 24 bits are the local address; in class B, the high order two bits are one-zero, the next 14 bits are the network and the last 16 bits are the local address; in class C, the high order three bits are Expires March 2003 [Page 11] Draft Revised Internet Protocol September 2002 one-one-zero, the next 21 bits are the network and the last 8 bits are the local address. For a C class GRID address 204.16.16.0, the example of the division map of Address Plane is as following: Address Address Plane ---------- ----------------- 204.16.16.0 ~ 204.16.16.127 data 204.16.16.127 ~ 204.16.16.159 video 204.16.16.160 ~ 204.16.16.191 voice 204.16.16.192 ~ 204.16.16.224 mobile 204.16.16.225 ~ 204.16.16.241 signaling 204.16.16.254 plane multicast We suggest to use a set of A class address for GRID inner IP address. For example, Data Plane identification address is fixed as "10", then 20 bits are the GRID network address, and the last 4 bits are the personality local address. Care must be taken in mapping Enhanced Internet addresses to hosts, a single GRID Boundary gateway must be able to act as if it were several distinct hosts to the plane extent of using several distinct Enhanced Internet addresses (multi-gateways). Some GRID Boundary gateways will also have several physical interfaces (multi-planes). The example of the IP addressing is as following: Network Class Address Description ---------- ----------------------------- ------------------- Internet A 1.0.0.0 ~ 127.255.255.255 public, exclude "F" B 128.0.0.0 ~ 191.255.255.255 exclude "G" C 192.0.0.0 ~ 223.255.255.255 exclude "H" Grid-net "F" 10.0.0.0 ~ 10.255.255.255 non-private, 20.0.0.0 ~ 20.255.255.255 used for different 30.0.0.0 ~ 30.255.255.255 physical plane D 232.0.0.0 ~ 232.255.255.255 inner multicast Intranet "F" 10.0.0.0 ~ 10.255.255.255 private, "G" 172.16.0.0 ~ 172.31.255.255 "H" 192.168.0.0 ~ 192.168.255.255 In GRID tier, it is also the task of higher level (i.e., host-to-host or application) protocols to make the mapping from target names to addresses. The GRID Domain Name Server maps names to GRID IP addresses. It is the task of lower level procedures (i.e. inner gateways in GRID) to make the mapping from GRID IP addresses to routes. Additionally, provision must be made for a host or a personnel to have several physical interfaces to the network, with each having several logical Enhanced Internet addresses. Here, 4 bits address space is suggested to provid for personality. There is a rule for address initiation in the Internet header: For source address it should be placed the current tier address, and for destination address it should be placed the top tier address. The address swapping process is as following: When the datagram is transmitted up to the internet tier, only the source address field is swapped by upper tier address (i.e. Internet tier address). Then the datagram is transmitted down to the destination Grid-net tier, the destination address field is swapped by lower Grid-net tier address. Expires March 2003 [Page 12] Draft Revised Internet Protocol September 2002 2.3.2. Fragmentation Fragmentation of an Enhanced internet datagram is necessary when it originates in a local net that allows a large packet size and must traverse a local net that limits packets to a smaller size to reach its destination. An Enhanced Internet datagram can also be marked "don't fragment." Any Enhanced Internet datagram so marked is not to be fragmented under any tier circumstances. If Enhanced Internet datagram marked don't fragment cannot be delivered to its destination without fragmenting it, it is to be discarded instead. Fragmentation, transmission and reassembly across a local network, which is invisible to the Internet protocol module, is called Intranet fragmentation. Fragmentation, transmission and reassembly across a Grid-net local network, which is visible to the Internet protocol module of a GRID Boundary gateway, is called Grid-net fragmentation, and should be effective for the GRID network. The Internet fragmentation and reassembly procedure needs to be able to break a datagram into an almost arbitrary number of pieces that can be later reassembled. The receiver of the fragments uses the identification field to ensure that fragments of different datagram are not mixed. The fragment-offset field tells the receiver the position of a fragment in the original datagram. The fragment offset and length determine the portion of the original datagram covered by this fragment. The more-fragments flag indicates (by being reset) the last fragment. These fields provide sufficient information to reassemble datagram. The identification field is used to distinguish the fragments of one datagram from those of another. The originating protocol module of an Enhanced Internet datagram sets the identification field to a value that must be unique for that source-destination pair and protocol for the time the datagram will be active in the Internet or the Grid-net system. The originating protocol module of a complete datagram sets the more-fragments flag to zero and the fragment offset to zero. To fragment a long Enhanced Internet datagram, an Internet or a Grid-net protocol module (for example, in a gateway), creates two new Enhanced Internet datagram and copies the contents of the Enhanced Internet header fields from the long datagram into both new Enhanced Interne headers. The data of the long datagram is divided into two portions on an 8 octet (64 bit) boundary (the second portion might not be an integral multiple of 8 octets, but the first must be). Call the number of 8 octet blocks in the first portion NFB (for Number of Fragment Blocks). The first portion of the data is placed in the first new Enhanced Internet datagram, the total length field is set to the length of the first datagram, and the more-fragments flag is set to one. The second portion of the data is placed in the second new Enhanced Internet datagram, the total length field is set to the length of the second datagram, and the more-fragments flag carries the same value as the long datagram. The fragment offset field of the second new Enhanced Internet datagram is set to the value of that field in the long datagram plus NFB. This procedure can be generalized for n-way split, rather than the two-way split described. To assemble the fragments of an Enhanced Expires March 2003 [Page 13] Draft Revised Internet Protocol September 2002 Internet datagram, an Internet or a Grid-net protocol module (for example at a destination host) combine Enhanced Internet datagram that all have the same value for the four to six fields: identification, source, destination, protocol, and attached source option, attached destination option if needed. The combination is done by placing the data portion of each fragment in the relative position indicated by the fragment offset in that fragment's Enhanced Internet header. The first fragment will have the fragment offset zero, and the last fragment will have the more-fragments flag reset to zero. 2.4. Gateways Gateways implement Enhanced Internet protocol to forward datagram between networks in the same or different tier. Gateways also implement the Gateway to Gateway Protocol (GGP) [7] to coordinate routing and other Internet control information. In a gateway the higher-level protocols need not be implemented and the GGP functions are added to the IP module. In a Grid Boundary gateway the IP address swapping function is added to the IP module. +-----------------------------------+ Internet Tier | Internet Protocol & ICMP & GGP | gateway +-----------------------------------+ | | +------------------------------------+ +----------+ | Internet Protocol & IP Swapping | | Local Net| | & ICMP & GGP | +----------+ +------------------------------------+ Grid Boundary gateway | | +-----------------------------------+ Grid-net Tier | Internet Protocol & ICMP & GGP | gateway +-----------------------------------+ | | +------------+ +-----------+ | Local Net | | Local Net | +------------+ +-----------+ Gateway Protocols Figure 5. 3. SPECIFICATION 3.1. Enhanced Internet Header Format There are two cases for the format of a Enhanced Internet Header: Case 1: Normal Case. Two 4-octet fields of Source Address and Destination Address, which are the same as Ipv4 usually be. This Format is used for those datagram, which is transmitted only in one Tier, either the Internet tier or the Grid-net tier. Case 2: Enhanced Case. Two 4-octet fields of Source Address and Destination Address, And a Fixed attached address option, which has 12-octet length, including an option-type octet, an option-length octet, and the 2-octet of Flow Labels, 4-octet of Source Address and 4-octet Expires March 2003 [Page 14] Draft Revised Internet Protocol September 2002 of Destination Address. This Format is used for those datagram, which is transmitted through the tier boundary gateway between the Internet tier and the Grid-net tier at least once. A summary of the contents of the Enhanced Internet header is as follows: Case 1: Normal Internet Header Format. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version|- IHL -|Type of Service|-------- Total Length ---------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-------- Identification -------|Flags|---- Fragment Offset ----| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-Time to Live--|-- Protocol ---|------- Header Checksum -------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |---------------------- Source Address -------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |--------------------- Destination Address ---------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |--------------------- Options -----------------|--- Padding ---| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Example Normal Internet Datagram Header Figure 6. Note that each tick mark represents one bit position. Case 2: Enhanced Internet Header Format. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version|- IHL -|Type of Service|-------- Total Length ---------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-------- Identification -------|Flags|---- Fragment Offset ----| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-Time to Live--|-- Protocol ---|------- Header Checksum -------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |---------------------- Source Address -------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |--------------------- Destination Address ---------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |- AAO Header --|- AAO Length --|--------- Flow Labels ---------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------ Attached Source Address --------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |---------------- Attached Destination Address -----------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-------------------- other Options ------------|--- Padding ---| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Example Enhanced Internet Datagram Header Figure 7. Note that each tick mark represents one bit position. Expires March 2003 [Page 15] Draft Revised Internet Protocol September 2002 3.1.1. Version: 4 bits The Version field indicates the format of the Enhanced Internet header. This document describes Enhanced version 4. 3.1.2. IHL: 4 bits Enhanced Internet Header Length is the length of the Enhanced Internet header in 32 bit words, and thus points to the beginning of the data. Note that the minimum value for a correct header is 5 for normal header. The example value for a Enhanced header is 8, where we add extra 3 of 32 bit words, including an Attached Source Address and an Attached Destination Address. 3.1.3. Type of Service: 8 bits The Type of Service provides an indication of the abstract parameters of the quality of service desired. These parameters are to be used to guide the selection of the actual service parameters when transmitting a datagram through a particular network. Several networks offer service precedence, which somehow treats high precedence traffic as more important than other traffic (generally by accepting only traffic above a certain precedence at time of high load). The major choice is a three-way tradeoff between low-delay, high-reliability, and high-throughput. Bits 0-2: Precedence. Bit 3: 0 = Normal Delay, 1 = Low Delay. Bit 4: 0 = Normal Throughput, 1 = High Throughput. Bit 5: 0 = Normal Reliability, 1 = High Reliability. Bit 6: reserved. Bit 7: reserved. 0 1 2 3 4 5 6 7 +-----+-----+------+-----+-----+-----+-----+-----+ |---- PRECEDENCE --|- D -|- T -|- R -| | | +-----+-----+------+-----+-----+-----+-----+-----+ Precedence 111 - Network Control 110 - Internetwork Control 101 - CRITIC/ECP 100 - Flash Override 011 - Flash 010 - Immediate 001 - Priority 000 - Routine IETF Diffserv (RFC2474) may supersede The ToS, use 6 bits of Differentiated Services Code Point (DSCP) to assign QoS for datagram. 0 1 2 3 4 5 6 7 +-----+-----+------+-----+-----+-----+-----+-----+ |------------- DSCP -----------------| | | +-----+-----+------+-----+-----+-----+-----+-----+ The type of service is used to specify the treatment of the datagram during its transmission through the Internet system. The use of the Delay, Throughput, and Reliability indications may increase the cost (in some sense) of the service. In many networks better performance for Expires March 2003 [Page 16] Draft Revised Internet Protocol September 2002 these parameters is processed in distribution way. Example mappings of the Internet type of service to the actual service provided on networks such as the EXP(Experimental) field of the MPLS header of RFC 3032. The Network Control precedence designation is intended to be used within a network only. The actual use and control of that designation is up to each network. The Internetwork Control designation is intended for use by gateway control originators only. If the actual use of these precedence designations is of concern to a particular network, it is the responsibility of that network to control the access to, and use of, those precedence designations. 3.1.4. Total Length: 16 bits Total Length is the length of the datagram, measured in octets, including Enhanced Internet header and data. This field allows the length of a datagram to be up to 65,535 octets. Such long datagram are suit for TCP, and are impractical for most hosts and networks. All hosts must be prepared to accept datagram of up to 576 octets (whether they arrive whole or in fragments). It is recommended that hosts only send datagram larger than 576 octets if they have assurance that the destination is prepared to accept the larger datagram. The number 576 is selected to allow a reasonable sized data block to be transmitted in addition to the required header information. For example, this size allows a data block of 512 octets plus 64 header octets to fit in a datagram. The maximal Enhanced Internet header is 60 octets, and a typical Enhanced Internet header is 32 octets, allowing a margin for headers of higher-level protocols. 3.1.5. Identification: 16 bits An identifying value assigned by the sender to aid in assembling the fragments of a datagram. 3.1.6. Flags: 3 bits Various Control Flags. Bit 0: reserved, must be zero Bit 1: (DF) 0 = May Fragment, 1 = Don't Fragment. Bit 2: (MF) 0 = Last Fragment, 1 = More Fragments. 0 1 2 +------+------+------+ | 0 | DF | MF | +------+------+------+ 3.1.7. Fragment Offset: 13 bits This field indicates where in the datagram this fragment belongs. The fragment offset is measured in units of 8 octets (64 bits). The first fragment has offset zero. 3.1.8. Time to Live: 8 bits This field indicates the maximum time the datagram is allowed to remain in the Internet system. If this field contains the value zero, then the Expires March 2003 [Page 17] Draft Revised Internet Protocol September 2002 datagram must be destroyed. This field is modified in Enhanced Internet header processing. The time is measured in units of seconds, but since every module that processes a datagram must decrease the TTL by at least one even if it process the datagram in less than a second, the TTL must be thought of only as an upper bound on the time a datagram may exist. The intention is to cause undeliverable datagram to be discarded, and to bound the maximum datagram lifetime. 3.1.9. Protocol: 8 bits This field indicates the next level protocol used in the data portion of the Enhanced Internet datagram. The values for various protocols are specified in "Assigned Numbers" [9]. For example, the value 51 in Protocol field represents Authentication. 3.1.10. Header Checksum: 16 bits A checksum on the header only. Since some header fields change (e.g., time to live), this is recomputed and verified at each point that the Enhanced Internet header is processed. The checksum algorithm is: The checksum field is the 16 bit one's complement of the one's complement sum of all 16-bit words in the header. For purposes of computing the checksum, the value of the checksum field is zero. This is a simple to compute checksum and experimental evidence indicates it is adequate, but it is provisional and may be replaced by a CRC procedure, depending on further experience. 3.1.11. AAO Header: 8 bits The AOO options Header may appear or not in datagram. They must be implemented by all IP modules (boundary gateways or host). For Enhanced Internet header the attached address option may added in all datagram, when transmitted across the Boundary between Internet tier and Grid-net tier. In some environments the Flow Labels may asignned in all datagram. The attached option field is fixed in length. There may followed by no or more variable options. The AAO Header octet is viewed as having 3 fields: 1 bit copied flag, always 1 = copied 2 bits option class, always 01 = attached IP address 5 bits option number. 0 1 2 3 4 5 6 7 +-----+-----+------+-----+-----+-----+-----+-----+ |flg=1|op-class=01 |- - -|- AGD|- AID|- AGS|- AIS| +-----+-----+------+-----+-----+-----+-----+-----+ The following Internet option bits are defined: AIS - attached Source Address, Used to indicate there is a 4 octets Internet IP Address of the source host. AGS - attached Source Address, Used to indicate there is a 4 octets Grid-net IP Address of the source host. AID - attached Destination Address, Used to indicate there is a 4 Octets Internet IP Address of the Destination host. AGD - attached Destination Address, Used to indicate there is a 4 octets Grid-net IP Address of the Destination host. Expires March 2003 [Page 18] Draft Revised Internet Protocol September 2002 For example AAO Header =161, if there is a attached Source Internet Address. 3.1.12. AAO Length: 8 bits AAO Length is always 12. 3.1.13. Flow Labels: 16 bits The 16-bit Flow Label field in the Enhanced Ipv4 header may be used by a source to label sequences of packets for which it requests special handling by the routers in Internet tier, such as non-default quality of service or "real-time" service. This aspect from IPv6 is still experimental and subject to change as the requirements for flow support in the Internet backbone. 3.1.14. Attached Source Address This Attached Source Address option appears at most once in a datagram. It provides a way for host to store source next tier's IP address of the host, and for Grid Boundary Gateway to swap the Source Address field by this address or it's Internet address for transmission throughout the Boundary, outbound to the Internet tier. This option should be copied on fragmentation. 3.1.15. Attached Destination Address This Attached Destination Address option appears at most once in a datagram. It provides a way for Grid Boundary Gateway to swap the destination address by this Address field, for transmission inbound to destination Grid-net. This option should be copied on fragmentation. 3.1.16. Options: variable The options may appear or not in datagram. They must be implemented by all IP modules (host and gateways). What is optional is their transmission in any particular datagram, not their implementation. In some environments the security option may be required in all datagram. The option field is variable in length. There may be zero or more options. There are two cases for the format of an option: Case 1: A single octet of option-type. ase 2: An option-type octet, an option-length octet, and the actual option-data octets. The option-length octet counts the option-type octet and the option-length octet as well as the option-data octets. The option-type octet is viewed as having 3 fields: 1 bit copied flag, 2 bits option class, 5 bits option number. The copied flag indicates that this option is copied into all fragments on fragmentation. Expires March 2003 [Page 19] Draft Revised Internet Protocol September 2002 0 = not copied 1 = copied The option classes are: 0 = control 1 = attached IP address, for fixed format in AAO above mentioned 2 = debugging and measurement 3 = Reserved The following Internet options are defined: Class Number Length Description ---- ------ ------ ----------- 0 0 - End of Option list. This option occupies only 1 octet; it has no length octet. 0 1 - No Operation. This option occupies only 1 Octet; it has no length octet. 0 2 11 - Security. Used to carry Security, Compartmentation, User Group (TCC), and Handling Restriction Code compatible with DOD Requirements. 0 3 var. - Loose Source Routing. Used to route the Enhanced Internet datagram based on information supplied by the source. 0 9 var. - Strict Source Routing. Used to route the Enhanced Internet datagram based on information supplied by the source. 0 7 var. - Record Route. Used to trace the route an Enhanced Internet datagram takes. 0 8 4 - Stream ID for multimedia. Used to carry the stream identifier. 2 4 var. - Internet Timestamp. 3.1.17. Padding: variable The Enhanced Internet header padding is used to ensure that the Enhanced Internet header ends on a 32-bit boundary. The padding is zero. 3.2. Specific Option Definitions 3.2.1. End of Option List +-----------+ | 00000000 | +-----------+ Type=0 This option indicates the end of the option list. This might not coincide with the end of the Enhanced Internet header according to the Enhanced Internet header length. This is used at the end of all options, not the end of each option, and need only be used if the end of the options would not otherwise coincide with the end of the Enhanced Internet header. May be copied, introduced, or deleted on fragmentation, or for any other reason. Expires March 2003 [Page 20] Draft Revised Internet Protocol September 2002 3.2.2. No Operation +-----------+ | 00000001 | +-----------+ Type=1 This option may be used between options, for example, to align the beginning of a subsequent option on a 32-bit boundary. May be copied, introduced, or deleted on fragmentation, or for any other reason. 3.2.3. Security This option provides a way for hosts to send security, compartmentation, handling restrictions, and TCC (closed user group) parameters. The format for this option is as follows: +---------+---------+---//-----+---//-----+---//------+---//----+ | 10000010| 00001011| SSS SSS| CCC CCC| HHH HHH| TCC | +---------+---------+---//-----+---//-----+---//------+---//----+ Type=130 Length=11 Security (S field): 16 bits Specifies one of 16 levels of security (eight of which are reserved for future use). 00000000 00000000 - Unclassified 11110001 00110101 - Confidential 01111000 10011010 - EFTO 10111100 01001101 - MMMM 01011110 00100110 - PROG 10101111 00010011 - Restricted 11010111 10001000 - Secret 01101011 11000101 - Top Secret 00110101 11100010 - (Reserved for future use) 10011010 11110001 - (Reserved for future use) 01001101 01111000 - (Reserved for future use) 00100100 10111101 - (Reserved for future use) 00010011 01011110 - (Reserved for future use) 10001001 10101111 - (Reserved for future use) 11000100 11010110 - (Reserved for future use) 11100010 01101011 - (Reserved for future use) Compartments (C field): 16 bits An all zero value is used when the information transmitted is not compartmented. Handling Restrictions (H field): 16 bits The values for the control and release markings are alphanumeric digraphs and are defined in the Defense Intelligence Agency Manual DIAM 65-19, "Standard Security Markings". Transmission Control Code (TCC field): 24 bits Provides a means to segregate traffic and define controlled communities of interest among subscribers. The TCC values are trigraphs, and are available from HQ DCA Code 530.Must be copied on fragmentation. This option appears at most once in a datagram. Expires March 2003 [Page 21] Draft Revised Internet Protocol September 2002 3.2.4. Loose Source and Record Route . +--------+---------+-------+-------//-----------+ . |10000011| length |pointer| route data | . +--------+---------+-------+-------//-----------+ Type=131 The loose source and record route (LSRR) option provides a means for the source of an Enhanced Internet datagram to supply routing information to be used by the gateways in forwarding the datagram to the destination (or destination Grid-net), and to record the route information. The option begins with the option type code. The second octet is the option length which includes the option type code and the length octet, the pointer octet, and length-3 octets of route data. The third octet is the pointer into the route data indicating the octet, which begins the next source address to be processed. The pointer is relative to this option, and the smallest legal value for the pointer is 4. A route data is composed of a series of Internet addresses or Grid-net address. Each address is 32 bits or 4 octets. If the pointer is greater than the length, the source route is empty (and the recorded route full) and the routing is to be based on the destination address field. If the Internet address in destination address field has been reached and the pointer is not greater than the length, the next address in the source route replaces the address in the destination address field, and the recorded route address replaces the source address just used, and pointer is increased by four. The recorded route address is the Internet module's own Internet address as known in the environment into which this datagram is being forwarded. This procedure of replacing the source route with the recorded route (though it is in the reverse of the order it must be in to be used as a source route) means the option (and the IP header as a whole) remains a constant length as the datagram progresses through the Internet. This option is a loose source route because the gateway or host IP is allowed to use any route of any number of other intermediate gateways to reach the next address in the route. This option must be copied on fragmentation. Appears at most once in a datagram. 3.2.5. Strict Source and Record Route +---------+--------+--------+------//---------+ | 10001001| length | pointer| route data | +---------+--------+--------+--- --//---------+ Type=137 The strict source and record route (SSRR) option provides a means for the source of an Internet datagram to supply routing information to be used by the gateways in forwarding the datagram to the destination, and to record the route information. The option begins with the option type code. The second octet is the option length, which includes the option type code and the length octet, the pointer octet, and length-3 octets of route data. The third octet is the pointer into the route data indicating the octet, which begins the next source address to be processed. The pointer is relative to this option, and the smallest legal value for the pointer is 4. A route data is composed of a series of Internet or Grid-net addresses. Expires March 2003 [Page 22] Draft Revised Internet Protocol September 2002 Each address is 32 bits (4 octets). If the pointer is greater than the length, the source route is empty (and the recorded route full) and the routing is to be based on the destination address field. If the address in destination address field has been reached and the pointer is not greater than the length, the next address in the source route replaces the address in the destination address field, and the recorded route address replaces the source address just used, and pointer is increased by four. The recorded route address is the Internet module's own current tier address as known in the environment into which this datagram is being forwarded. This procedure of replacing the source route with the recorded route (though it is in the reverse of the order it must be in to be used as a source route) means the option (and the IP header as a whole) remains a constant length as the datagram progresses through the Internet. This option is a strict source route because the gateway or host IP must send the datagram directly to the next address in the source route through only the directly connected network indicated in the next address to reach the next gateway or host specified in the route. Must be copied on fragmentation. Appears at most once in a datagram. 3.2.6. Record Route +--------+--------+--------+-----//--------+ |00000111| length | pointer| route data | +--------+--------+--------+-----//--------+ Type=7 The record route option provides a means to record the route of an Internet datagram. The option begins with the option type code. The second octet is the option length which includes the option type code and the length octet, the pointer octet, and length-3 octets of route data. The third octet is the pointer into the route data indicating the octet, which begins the next area to store a route address. The pointer is relative to this option, and the smallest legal value for the pointer is 4. A recorded route is composed of a series of Internet addresses. Each Internet address is 32 bits or 4 octets. If the pointer is greater than the length, the recorded route data area is full. The originating host must compose this option with a large enough route data area to hold all the address expected. The size of the option does not change due to adding addresses. The initial contents of the route data area must be zero. When an Internet module routes a datagram it checks to see if the record route option is present. If it is, it inserts its own internet address as known in the environment into which this datagram is being forwarded into the recorded route beginning at the octet indicated by the pointer, and increments the pointer by four. If the route data area is already full (the pointer exceeds the length) the datagram is forwarded without inserting the address into the recorded route. If there is some room but not enough room for a full address to be inserted, the original datagram is considered to be in error and is discarded. In either case an ICMP parameter problem message may be sent to the source host [3]. Not copied on fragmentation, goes in first fragment only. Appears at most once in a datagram. Expires March 2003 [Page 23] Draft Revised Internet Protocol September 2002 3.2.7. Stream Identifier +--------+--------+-------+------+ |10001000|00000100| Stream ID | +--------+--------+-------+------+ Type=136 Length=4 This option provides a way for the 16-bit SATNET stream identifier to be carried through networks that do not support the stream concept. Must be copied on fragmentation. Appears at most once in a datagram. 3.2.8. Enhanced Internet Timestamp +--------+--------+--------+----------+ |01000100| length | pointer|oflw |flg | +--------+--------+--------+----------+ | current tier address | +--------+--------+--------+----------+ | Timestamp | +--------+--------+--------+----------+ Type = 68 The Option Length is the number of octets in the option counting the type, length, pointer, and overflow/flag octets (maximum length 40). The Pointer is the number of octets from the beginning of this option to the end of timestamps plus one (i.e., it points to the octet beginning the space for next timestamp). The smallest legal value is 5. The timestamp area is full when the pointer is greater than the length. The Overflow (oflw) [4 bits] is the number of IP modules that cannot register timestamps due to lack of space. The Flag (flg) [4 bits] values are 0 -- time stamps only, stored in consecutive 32-bit words, 1 -- each timestamp is preceded with current tier address of the registering entity, 3 -- the Internet address fields are prespecified. An IP module only registers its timestamp if it matches its own address with the next specified Internet address. For those IP module in Grid-net tier, the current tier address should be their own Grid-net address. The Timestamp is a right-justified, 32-bit timestamp in milliseconds since midnight UT. If the time is not available in milliseconds or cannot be provided with respect to midnight UT, then Local Time may be inserted as a timestamp provided the high order bit of the timestamp field is set to one to indicate the use of a non-standard value. The originating host must compose this option with a large enough timestamp data area to hold all the timestamp information expected. The size of the option does not change due to adding Timestamps. The initial contents of the timestamp data area must be zero or current tier address/zero pairs. If the timestamp data area is already full (the pointer exceeds the length) the datagram is forwarded without inserting the timestamp, but the overflow count is incremented by one. If there is some room but not enough room for a full timestamp to be inserted, or the overflow count itself overflows, the original datagram is considered to be in error and is discarded. In either case an ICMP parameter problem message may be sent to the source host [3]. Expires March 2003 [Page 24] Draft Revised Internet Protocol September 2002 The timestamp option is not copied upon fragmentation. It is carried in the first fragment. Appears at most once in a datagram. 3.3. Discussion The implementation of Enhanced Internet protocol must be robust. Each implementation must expect to interoperate with others created by different individuals. While the goal of this specification is to be explicit about the protocol there is the possibility of differing Interpretations. In general, an implementation must be conservative in its sending behavior, and liberal in its receiving behavior. That is, it must be careful to send well-formed datagram, but must accept any datagram that it can interpret (e.g., not object to technical errors where the meaning is still clear). The basic internet service is datagram oriented and provides for the fragmentation of datagram at gateways, with reassembly taking place at the destination internet protocol module in the destination host. Of course, fragmentation and reassembly of datagram within a network or by private agreement between the gateways of a network is also allowed since this is transparent to the Enhanced Internet protocols and the higher-level protocols. This transparent type of fragmentation and reassembly is termed "network-dependent" (or Intranet) fragmentation and is not discussed further here. Enhanced Internet addresses distinguish sources and destinations to the host level, which is compatible with original Internet protocols, and provide a protocol field as well. It is assumed that each protocol will provide for whatever multiplexing is necessary within a host. 3.3.1. Addressing Address Formats: Tier High Order Bits Format Class ----- ----------------- -------- ------- Internet 0 7 bits of net, 24 bits of host A 1.0.0.0 ~ 127.255.255.255 10 14 bits of net, 16 bits of host B 128.0.0.0 ~ 191.255.255.255 110 21 bits of net, 8 bits of host C 192.0.0.0 ~ 223.255.255.255 Grid-net 0 24 bits of host A 10.0.0.0 ~ 10.255.255.255 multicast 1110 24 bits of host D (for grid-net) 232.0.0.0 ~ 232.255.255.255 Intranet 10 16 bits of host B 172.16.0.0 ~ 172.31.255.255 110 8 bits of host C 192.168.0.0 ~ 192.168.255.255 To provide for flexibility in assigning address to networks and allow for the large number of small to intermediate sized networks the interpretation of the address field is coded to specify a small number of networks with a large number of host, a moderate number of networks with a moderate number of hosts, and a large number of networks with a small number of hosts. In addition there is an escape code for extended addressing mode. Expires March 2003 [Page 25] Draft Revised Internet Protocol September 2002 A value of zero in the network field means this network. This is only used in certain ICMP messages. The actual values assigned for network addresses is given in "Assigned Numbers" [9]. The tier address, assigned by the local service provider, must allow for a single physical host to act as several distinct hosts. That is, there must be a mapping between host addresses and network/host interfaces that allows several Enhanced Internet addresses to correspond to one interface. It must also be allowed for a host to have several physical interfaces and to treat the datagram from several of them as if they were all addressed to a single host, these are specifically useful for Grid-net Address Plane. 3.3.2. Example Address Swapping The Grid-net Boundary gateway processes address swapping of each outbound datagram, which checks if the destination would be an Internet Address, and the source would be an Grid-net Address. The fields which may be affected by address swapping include: (1) source field (2) header length (3) Attached Source option field (4) Total Length (5) header checksum Notation: SO - Source Address ASO - Attached Source Option GSI - Grid-net Gateway Internet Source Address NIHL - New Internet Header Length OO - Option Offset AAOH - Attached Address Option Header AAOL - Attached Address Option Length AISOH - attached Option Header with Internet Source bit on AGSOH - attached Option Header with Grid-net Source bit on TL - Total Length OSO - Old Source OASO - Old Attached Source Option OIHL - Old Internet Header Length OTL - Old Total Length Procedure: IF Destination not in Internet Address Set THEN discard the datagram IF Source not in Grid-net Address Set THEN discard the datagram ELSE To swap the Source address: (1) Copy the original Enhanced Internet header; (2) OSO <- SO; (3) IF ((AAOH && AISOH)== AISOH ) IF Attached Source Option is Internet Address of the Grid-net THEN SO <- ASO.S; ASO <- OSO; AAOH <- ((AAOH | AGS)& not AIS); ELSE discard the datagram ELSE To insert a Source address option: Move the option portion from OO down 12 octets offset; SO <- GSI; ASO <- GSOH+ OSO; AAOH <- 162; AAOL <- 12; Expires March 2003 [Page 26] Draft Revised Internet Protocol September 2002 NIHL <- OIHL+3; TL <- OTL+12; (4) Correct the header: Recompute Checksum; (5) Submit this datagram to the test; DONE. 3.3.3. Compatibility The Enhanced Internet Protocol is compatible with the original internet protocol, so at the very beginning when the Grid-net being set up, not all Web server can handle the attached address option, the hosts inside the Grid-net can operate as if in the lower Intranet tier. IE Browser inside the Grid-net can access World Wide Web by local Proxy as usual. 3.3.4. Fragmentation and Reassembly. The Internet identification field (ID) is used together with the source and destination address, and the protocol fields, to identify datagram fragments for reassembly. The More Fragments flag bit (MF) is set if the datagram is not the last fragment. The Fragment Offset field identifies the fragment location, relative to the beginning of the original unfragmented datagram. Fragments are counted in units of 8 octets. The fragmentation strategy is designed so, then an unfragmented datagram has all zero fragmentation information (MF = 0, fragment offset = 0). If an Enhanced Internet datagram is fragmented, its data portion must be broken on 8 octet boundaries. This format allows 2**13 = 8192 fragments of 8 octets each for a total of 65,536 octets. Note that this is consistent with the datagram total length field (of course, the header is counted in the total length and not in the fragments). When fragmentation occurs, some options are copied, but others remain with the first fragment only. Every Internet module must be able to forward a datagram of 68 octets without further fragmentation. This is because an Enhanced Internet header may be up to 60 octets, and the minimum fragment is 8 octets. Every Enhanced Internet destination must be able to receive a datagram of 576 octets either in one piece or in fragments to be reassembled. The fields which may be affected by fragmentation include: (1) options field (2) more fragments flag (3) fragment offset (4) Enhanced internet header length field (5) total length field (6) header checksum If the Don't Fragment flag (DF) bit is set, then fragmentation of this datagram is NOT permitted, although it may be discarded. This can be used to prohibit fragmentation in cases where the receiving host does not have sufficient resources to reassemble Enhanced internet fragments. One example of use of the Don't Fragment feature is to down line load a small host. A small host could have a boot strap program that accepts a datagram stores it in memory and then executes it. The fragmentation and reassembly procedures are most easily described by examples. The following procedures are example implementations. Expires March 2003 [Page 27] Draft Revised Internet Protocol September 2002 General notation in the following pseudo programs: "=<" means "less than or equal", "#" means "not equal", "=" means "equal", "<-" means "is set to". Also, "x to y" includes x and excludes y; for example, "4 to 7" would include 4, 5, and 6 (but not 7). 3.3.5. Example Fragmentation Procedure The maximum sized datagram that can be transmitted through the next network is called the maximum transmission unit (MTU). If the total length is less than or equal the maximum transmission unit then submit this datagram to the next step in datagram processing; otherwise cut the datagram into two fragments, the first fragment being the maximum size, and the second fragment being the rest of the datagram. The first fragment is submitted to the next step in datagram processing, while the second fragment is submitted to this procedure in case it is still too large. Notation: FO - Fragment Offset IHL - Enhanced internet Header Length DF - Don't Fragment flag MF - More Fragments flag TL - Total Length OFO - Old Fragment Offset OIHL - Old Internet Header Length OMF - Old More Fragments flag OTL - Old Total Length NFB - Number of Fragment Blocks MTU - Maximum Transmission Unit Procedure: IF TL =< MTU THEN Submit this datagram to the next step in datagram processing ELSE IF DF = 1 THEN discard the datagram ELSE To produce the first fragment: (1) Copy the original Enhanced internet header; (2) OIHL <- IHL; OTL <- TL; OFO <- FO; OMF <- MF; (3) NFB <- (MTU-IHL*4)/8; (4) Attach the first NFB*8 data octets; (5) Correct the header: MF <- 1; TL <- (IHL*4)+(NFB*8); Recompute Checksum; (6) Submit this fragment to the next step in datagram processing; To produce the second fragment: (7) Selectively copy the Enhanced internet header (some options are not copied, see option definitions); (8) Append the remaining data; (9) Correct the header: IHL <- (((OIHL*4)-(length of options not copied))+3)/4; TL <- OTL - NFB*8 - (OIHL-IHL)*4); FO <- OFO + NFB; MF <- OMF; Recompute Checksum; (10) Submit this fragment to the fragmentation test; DONE. Expires March 2003 [Page 28] Draft Revised Internet Protocol September 2002 In the above procedure each fragment (except the last) was made the maximum allowable size. An alternative might produce less than the maximum size datagrams. For example, one could implement a fragmentation procedure that repeatly divided large datagrams in half until the resulting fragments were less than the maximum transmission unit size. 3.3.6. Example Reassembly Procedure For each datagram the buffer identifier is computed as the concatenation of the source, destination, protocol, and identification fields. If this is a whole datagram (that is both the fragment offset and the more fragments fields are zero), then any reassembly resources associated with this buffer identifier are released and the datagram is forwarded to the next step in datagram processing. If no other fragment with this buffer identifier is on hand then reassembly resources are allocated. The reassembly resources consist of a data buffer, a header buffer, a fragment block bit table, a total data length field, and a timer. The data from the fragment is placed in the data buffer according to its fragment offset and length, and bits are set in the fragment block bit table corresponding to the fragment blocks received. If this is the first fragment (that is the fragment offset is zero) this header is placed in the header buffer. If this is the last fragment ( that is the more fragments field is zero) the total data length is computed. If this fragment completes the datagram (tested by checking the bits set in the fragment block table), then the datagram is sent to the next step in datagram processing; otherwise the timer is set to the maximum of the current timer value and the value of the time to live field from this fragment; and the reassembly routine gives up control. If the timer runs out, the all reassembly resources for this buffer identifier are released. The initial setting of the timer is a lower bound on the reassembly waiting time. This is because the waiting time will be increased if the Time to Live in the arriving fragment is greater than the current timer value but will not be decreased if it is less. The maximum this timer value could reach is the maximum time to live (approximately 4.25 minutes). The current recommendation for the initial timer setting is 15 seconds. This may be changed as experience with this protocol accumulates. Note that the choice of this parameter value is related to the buffer capacity available and the data rate of the transmission medium; that is, data rate times timer value equals buffer size (e.g., 10Kb/s X 15s = 150Kb). Notation: FO - Fragment Offset IHL - Enhanced internet Header Length MF - More Fragments flag TTL - Time To Live NFB - Number of Fragment Blocks TL - Total Length TDL - Total Data Length BUFID - Buffer Identifier RCVBT - Fragment Received Bit Table TLB - Timer Lower Bound Expires March 2003 [Page 29] Draft Revised Internet Protocol September 2002 Procedure: (1) BUFID <- source|destination|protocol|identification; (2) IF FO = 0 AND MF = 0 (3) THEN IF buffer with BUFID is allocated (4) THEN flush all reassembly for this BUFID; (5) Submit datagram to next step; DONE. (6) ELSE IF no buffer with BUFID is allocated (7) THEN allocate reassembly resources with BUFID; TIMER <- TLB; TDL <- 0; (8) put data from fragment into data buffer with BUFID from octet FO*8 to octet (TL-(IHL*4))+FO*8; (9) set RCVBT bits from FO to FO+((TL-(IHL*4)+7)/8); (10) IF MF = 0 THEN TDL <- TL-(IHL*4)+(FO*8) (11) IF FO = 0 THEN put header in header buffer (12) IF TDL # 0 (13) AND all RCVBT bits from 0 to (TDL+7)/8 are set (14) THEN TL <- TDL+(IHL*4) (15) Submit datagram to next step; (16) free all reassembly resources for this BUFID; DONE. (17) TIMER <- MAX(TIMER,TTL); (18) give up until next fragment or timer expires; (19) timer expires: flush all reassembly with this BUFID; DONE. In the case that two or more fragments contain the same data either identically or through a partial overlap, this procedure will use the more recently arrived copy in the data buffer and datagram delivered. 3.3.7. Identification The choice of the Identifier for a datagram is based on the need to provide a way to uniquely identify the fragments of a particular datagram. The protocol module assembling fragments judges fragments to belong to the same datagram if they have the same source (or pair), destination (or pair), protocol, and Identifier. Thus, the sender must choose the Identifier to be unique for these source (or pair), destination (or pair) and protocol for the time the datagram (or any fragment of it) could be alive in the internet. It seems then that a sending Internet module needs to keep a table of Identifiers, one entry for each destination it has communicated with in the last maximum packet lifetime for the internet. However, since the Identifier field allows 65,536 different values, some host may be able to simply use unique identifiers independent of destination. It is appropriate for some higher level protocols to choose the identifier. For example, TCP protocol modules may retransmit an identical TCP segment, and the probability for correct reception would be enhanced if the retransmission carried the same identifier as the original transmission since fragments of either datagram could be used to construct a correct TCP segment. 3.3.8. Type of Service The type of service (TOS) is for internet service quality selection. The type of service is specified along the abstract parameters precedence, delay, throughput, and reliability. These abstract Expires March 2003 [Page 30] Draft Revised Internet Protocol September 2002 parameters are to be mapped into the actual service parameters of the particular networks the datagram traverses. Precedence. An independent measure of the importance of this datagram. Delay. Prompt delivery is important for datagram with this indication. Throughput. High data rate is important for datagram with this indication. Reliability. A higher level of effort to ensure delivery is important for datagram with this indication. For example, the ARPANET has a priority bit, and a choice between "standard" messages (type 0) and "uncontrolled" messages (type 3), (the choice between single packet and multipacket messages can also be considered a service parameter). The uncontrolled messages tend to be less reliably delivered and suffer less delay. Suppose an Internet datagram is to be sent through the ARPANET. Let the internet type of service be given as: Precedence: 5 Delay: 0 Throughput: 1 Reliability: 1 In this example, the mapping of these parameters to those available for the ARPANET would be to set the ARPANET priority bit on since the Internet precedence is in the upper half of its range, to select standard messages since the throughput and reliability requirement are indicated and delay is not. More details are given on service mappings in "Service Mappings" [8]. 3.3.9. Time to Live The time to live is set by the sender to the maximum time the datagram is allowed to be in the internet system. If the datagram is in the internet system longer than the time to live, then the datagram must be destroyed. This field must be decreased at each point that the internet header is processed to reflect the time spent processing the datagram. Even if no local information is available on the time actually spent, the field must be decremented by 1. The time is measured in units of seconds (i.e. the value 1 means one second). Thus, the maximum time to live is 255 seconds or 4.25 minutes. Since every module that processes a datagram must decrease the TTL by at least one even if it process the datagram in less than a second, the TTL must be thought of only as an upper bound on the time a datagram may exist. The intention is to cause undeliverable datagrams to be discarded, and to bound the maximum datagram lifetime. Some higher level reliable connection protocols are based on assumptions that old duplicate datagrams will not arrive after a certain time elapses. The TTL is a way for such protocols to have an assurance that their assumption is met. 3.3.10. Options The options are optional in each datagram, but required in implementations. That is, the presence or absence of an option is the choice of the sender, but each internet module must be able to parse every option. There can be several options present in the option field. The options might not end on a 32-bit boundary. The Internet header and Expires March 2003 [Page 31] Draft Revised Internet Protocol September 2002 the Enhanced Internet header must be filled out with octets of zeros. The first of these would be interpreted as the end-of-options option, and the remainder as Internet header padding. Every Iinternet module must be able to act on every option. The attached address option is only required be processed by Grid Boundary Gateway. The Security Option is required if classified, restricted, or compartmented traffic is to be passed. 3.3.11. Checksum The internet header checksum is recomputed if the internet header is changed. For example, a reduction of the time to live, additions or changes to internet options, or due to fragmentation. This checksum at the internet level is intended to protect the internet header fields from transmission errors. For Internet address swapping the IP address data only change their position, so the internet header checksum should not be changed. There are some applications where a few data bit errors are acceptable while retransmission delays are not. If the internet protocol enforced data correctness such applications could not be supported. 3.3.12. Errors Internet protocol errors may be reported via the ICMP messages [3]. 3.4. Interfaces The functional description of user interfaces to the IP is, at best, fictional, since every operating system will have different facilities. Consequently, we must warn readers that different IP implementations may have different user interfaces. However, all IPs must provide a certain minimum set of services to guarantee that all IP implementations can support the same protocol hierarchy. This section specifies the functional interfaces required of all IP implementations. Internet protocol interfaces on one side to the local network and on the other side to either a higher level protocol or an application program. In the following, the higher level protocol or application program (or even a gateway program) will be called the "user" since it is using the internet module. Since internet protocol is a datagram protocol, there is minimal memory or state maintained between datagram transmissions, and each call on the internet protocol module by the user supplies all information necessary for the IP to perform the service requested. 3.4.1. An Example Upper Level Interface The following example calls satisfy the requirements for the user to TCP protocol module, and TCP protocol module to internet protocol module communications ("=>" means returns): Calls for the user to TCP protocol module are: OPEN (local port, foreign socket, active/passive [, timeout] [, precedence] [, security/compartment] [, options]) , local connection name => result) SEND (local connection name, buffer address, byte count, PUSH flag, Expires March 2003 [Page 32] Draft Revised Internet Protocol September 2002 URGENT flag [,timeout]) Then the TCP protocol module create a transmission control blockú¿TCBú¨ú¼ where the parameters come from OPEN call. In sequence, send call for the TCP protocol module to internet protocol module is: SEND (srcc, srcu, dsti, dstg, prot, TOS, TTL, BufPTR, len, Id, DF, opt => result) where: srcc = current tier source address, nonblank srcu = upper tier source address, if there is dsth = higher tier destination address, nonblank dstl = lower tier destination address, if there is prot = protocol TOS = type of service TTL = time to live BufPTR = buffer pointer len = length of buffer Id = Identifier DF = Don't Fragment opt = option data result = response OK = datagram sent ok Error = error in arguments or local network error Note that the precedence is included in the TOS and the security/compartment is passed as an option. A receive call for the user to TCP protocol module is: RECEIVE (local connection name, buffer address, => byte count, urgent flag, push flag) In sequence, receive call for the TCP protocol module to internet protocol module is: RECV (BufPTR, prot, => result, srcc, srcu, dsth, dstl, TOS, len, opt) where: BufPTR = buffer pointer prot = protocol result = response OK = datagram received ok Error = error in arguments len = length of buffer srcc = current tier source address, nonblank srcu = upper tier source address, if there is dsth = higher tier destination address, nonblank dstl = lower tier destination address, if there is TOS = type of service opt = option data When the user sends a datagram, it executes the SEND call supplying all the arguments. The internet protocol module, in sequence on receiving this call, checks the arguments and prepares and sends the message. If the arguments are good and the datagram is accepted by the local network, the call returns successfully. If either the arguments are bad, or the datagram is not accepted by the local network, the call returns unsuccessfully. On unsuccessful returns, a reasonable report must be made as to the cause of the problem, but the details of such reports are up to individual implementations. When a datagram arrives at the internet protocol module from the local network, there are three cases: Expires March 2003 [Page 33] Draft Revised Internet Protocol September 2002 firstly there is a Boundary gateway have received the datagram but there is not a high level call, secondly there is a pending RECV call from the user addressed, or thirdly there is not a pending RECV call. In the first case, If the next tier address does not exist, an ICMP error message is returned to the sender, and the data is discarded. In the second case, the pending call is satisfied by passing the information from the datagram to the user. In the third case, the user addressed is notified of a pending datagram. If the user addressed does not exist, an ICMP error message is returned to the sender, and the data is discarded. The notification of a user may be via a pseudo interrupt or similar mechanism, as appropriate in the particular operating system environment of the implementation. A user's RECV call may then either be immediately satisfied by a pending datagram, or the call may be pending until a datagram arrives. The source address is included in the send call in case the sending host has several addresses (multi-tier addresses or multiple physical connections or logical addresses). The internet module must check to see that the source address is one or two of the legal address for this host. An implementation may also allow or require a call to the internet module to indicate interest in or reserve exclusive use of a class of datagrams (e.g., all those with a certain value in the protocol field). This section functionally characterizes a USER/IP interface. The notation used is similar to most procedure of function calls in high level languages, but this usage is not meant to rule out trap type service calls (e.g., SVCs, UUOs, EMTs), or any other form of inter-process communication. 4. APPENDIX 4.1. APPENDIX A: Examples & Scenarios 4.1.1. Example 1: This is an example of the internet datagram carrying attached Internet Source Address: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Ver= 4 |IHL= 7 |Type of Service|-------Total Length = 30-------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identification = 111 |Flg=0| Fragment Offset = 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |---Time = 123--|-Protocol = 1--|--------header checksum--------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-----------------current tier source address-------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-----------------------destination address---------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |---AAOH = 161--|--AAOL = 12 ---|-------------- 0 --------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-------------------- Attached Source Address ------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires March 2003 [Page 34] Draft Revised Internet Protocol September 2002 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------------ 0 ------------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | data | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Example Internet Datagram Figure 7. Note that each tick mark represents one bit position. This is an internet datagram in version 4 of Enhanced Internet Protocol; the internet header consists of seven 32 bit words, and the total length of the datagram is 30 octets. This datagram is a complete datagram (not a fragment). 4.1.2. Example 2: In this example, we show first a moderate size internet datagram (452 data octets), then two internet fragments that might result from the fragmentation of this datagram if the maximum sized transmission allowed were 280 octets. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Ver= 4 |IHL= 5 |Type of Service|------Total Length = 472-------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-----Identification = 111------|Flg=0|-----Fragment Offset = 0-| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |--Time = 123---|--Protocol = 6-|-------header checksum---------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------source address-------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |----------------------destination address----------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------------data-----------------------------| \------------------------------data-----------------------------\ |------------------------------data-----------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |---------data------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Example Internet Datagram Figure 8. Now the first fragment that results from splitting the datagram after 256 data octets. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Ver= 4 |IHL= 5 |Type of Service|------Total Length = 276-------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |----Identification = 111-------|Flg=1|---Fragment Offset = 0---| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |--Time = 119---| Protocol = 6 |------- Header Checksum -------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------ source address -----------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires March 2003 [Page 35] Draft Revised Internet Protocol September 2002 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |--------------------- destination address ---------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------------ data ---------------------------| \------------------------------ data ---------------------------\ |------------------------------ data ---------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------------ data ---------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Example Internet Fragment Figure 9. And the second fragment. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Ver= 4 |IHL= 5 |Type of Service|----- Total Length = 216 ------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |----- Identification = 111 ----|Flg=0|- Fragment Offset = 32 --| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-- Time = 119 -|- Protocol = 6 |------- Header Checksum -------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------ source address -----------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |--------------------- destination address ---------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------------ data ---------------------------| \------------------------------ data ---------------------------\ |------------------------------ data ---------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------ data -------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Example Internet Fragment Figure 10. 4.1.3. Example 3: Here, we show an example of a datagram containing attached address options, which has been send by a Host in Grid-net A, and now is transmitted throughout Internet, and will send to a destination in Grid-net B: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ver= 4|IHL= 8 |Type of Service|----- Total Length = 576 ------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |----- Identification = 111-----|Flg=0|-- Fragment Offset = 0 --| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires March 2003 [Page 36] Draft Revised Internet Protocol September 2002 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |-- Time = 100 -|- Protocol = 6 |------- Header Checksum -------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |----------------- current tier source address -----------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |--------------- destination Internet address -----------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |AAO Header =166|-Opt.Len = 12--| 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | attached Internet source address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | attached Grid-net B destination address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |------------------------------ data ---------------------------| \------------------------------ data ---------------------------\ |------------------------------ data ---------------------------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Example Internet Datagram Figure 11 4.2. APPENDIX B: Data Transmission Order The order of transmission of the header and data described in this document is resolved to the octet level. For example, in the following diagram the octets are transmitted in the order they are numbered. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |----- 1 -------|----- 2 -------|----- 3 -------|----- 4 -------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |----- 5 -------|----- 6 -------|----- 7 -------|----- 8 -------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |----- 9 -------|----- 10 ------|----- 11 ------|----- 12 ------| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Transmission Order of Bytes Figure 12. Whenever an octet represents a numeric quantity the left most bit in the diagram is the high order or most significant bit. That is, the bit labeled 0 is the most significant bit. For example, the following diagram represents the value 170 (decimal). 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |1 0 1 0 1 0 1 0| +-+-+-+-+-+-+-+-+ Significance of Bits Figure 13. Expires March 2003 [Page 37] Draft Revised Internet Protocol September 2002 Similarly, whenever a multi-octet field represents a numeric quantity the left most bit of the whole field is the most significant bit. When a multi-octet quantity is transmitted the most significant octet is transmitted first. 5. GLOSSARY Destination The destination address, an internet header field. DF The Don't Fragment bit carried in the flags field. Flags An internet header field carrying various control flags. Fragment Offset This internet header field indicates where in the internet datagram a fragment belongs. GGP Gateway to Gateway Protocol, the protocol used primarily between gateways to control routing and other gateway functions. header Control information at the beginning of a message, segment, datagram, packet or block of data. ICMP Internet Control Message Protocol, implemented in the internet module, the ICMP is used from gateways to hosts and between hosts to report errors and make routing suggestions. Identification An internet header field carrying the identifying value assigned by the sender to aid in assembling the fragments of a datagram. IHL The internet header field Internet Header Length is the length of the internet header measured in 32 bit words. IMP The Interface Message Processor, the packet switch of the ARPANET. Internet Address A four octet (32 bit) or eight octet (64 bit) source or destination address consisting of a Network address field and a attached tier Address option field. internet datagram The unit of data exchanged between a pair of internet modules (includes the internet header). internet fragment A portion of the data of an internet datagram with an internet header. Local Address The address of a host within a network. The actual mapping of an internet local address on to the host addresses in a network is quite general, allowing for many to one mappings. MF The More-Fragments Flag carried in the internet header flags field. module An implementation, usually in software, of a protocol or other procedure. Expires March 2003 [Page 38] Draft Revised Internet Protocol September 2002 more-fragments flag A flag indicating whether or not this internet datagram contains the end of an internet datagram, carried in the internet header Flags field. NFB The Number of Fragment Blocks in a the data portion of an internet fragment. That is, the length of a portion of data measured in 8 octet units. octet An eight bit byte. Options The internet header Options field may contain several options, and each option may be several octets in length. Padding The internet header Padding field is used to ensure that the data begins on 32 bit word boundary. The padding is zero. Protocol In this document, the next higher level protocol identifier, an internet header field. Rest The local address portion of an Internet Address. Source The source address, an internet header field. TCP Transmission Control Protocol: A host-to-host protocol for reliable communication in internet environments. TCP Segment The unit of data exchanged between TCP modules (including the TCP header). TFTP Trivial File Transfer Protocol: A simple file transfer protocol built on UDP. Time to Live An internet header field which indicates the upper bound on how long this internet datagram may exist. TOS Type of Service Total Length The internet header field Total Length is the length of the datagram in octets including internet header and data. TTL Time to Live Type of Service An internet header field which indicates the type (or quality) of service for this internet datagram. UDP User Datagram Protocol: A user level protocol for transaction oriented applications. User The user of the internet protocol. This may be a higher level protocol module, an application program, or a gateway program. Version The Version field indicates the format of the internet header. Expires March 2003 [Page 39] Draft Revised Internet Protocol September 2002 6. REFERENCES [1] Cerf, V., "The Catenet Model for Internetworking," Information Processing Techniques Office, Defense Advanced Research Projects Agency, IEN 48, July 1978. [2] Bolt Beranek and Newman, "Specification for the Interconnection of a Host and an IMP," BBN Technical Report 1822, Revised May 1978. [3] Postel, J., "Internet Control Message Protocol - DARPA Internet Program Protocol Specification," RFC 792, USC/Information Sciences Institute, September 1981. [4] Shoch, J., "Inter-Network Naming, Addressing, and Routing," COMPCON, IEEE Computer Society, Fall 1978. [5] Postel, J., "Address Mappings," RFC 796, USC/Information Sciences Institute, September 1981. [6] Shoch, J., "Packet Fragmentation in Inter-Network Protocols," Computer Networks, v. 3, n. 1, February 1979. [7] Strazisar, V., "How to Build a Gateway", IEN 109, Bolt Beranek and Newman, August 1979. [8] Postel, J., "Service Mappings," RFC 795, USC/Information Sciences Institute, September 1981. [9] Postel, J., "Assigned Numbers," RFC 790, USC/Information Sciences Institute, September 1981. [10] Kent, S., and R. Atkinson, "Security Architecture for the Internet Protocol", RFC 2401, November 1998. [11] Kent, S., and R. Atkinson, "IP Encapsulating Security Payload (ESP)", RFC 2406, November 1998. 7. Authors' Addresses Yunqing Zeng Internet Department MCM/Shenzhen Modern Computer Manufacture Limited Corp. 4 South Avenue High-tech Park, Shezhen 518057 Phone: +86 755-6616888-6111 Fax: +86 755-6635988 Email: zengyq@mcm.com.cn Expires March 2003 [Page 40]