INTERNET-DRAFT W. Biemolt, SEC NGTRANS WG M. Kaat, SEC April 1999 R. van der Pol, SURFnet H. Steenman, AT&T A Guide to the Introduction of IPv6 in the IPv4 World Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Distribution of this memo is unlimited. Abstract This document is a guide to the introduction of IPv6 in the current IPv4 based Internet or Intranets. Several general issues to start IPv6 networking in a predominantly IPv4 world are discussed, such as how to obtain IPv6 address space, IPv6 DNS and routing issues. Short descriptions are given of the different translation and migration tools that translate between IPv6 and IPv4 and/or tunnel IPv6 over IPv4. The remainder of the document describes how IPv6 can be introduced in various environments, such as ISPs, Internet Exchanges and end user environments and suggestions are given on the use of the different translation and migration tools. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 1] Internet Draft Guide to IPv6 Transition Apr 1999 Table of Contents Status of this Memo..............................................1 1. Introduction .................................................3 2. General IPv6 implementation issues............................3 2.1 IPv6 address assignments.. ................................4 2.1.1 Obtaining IPv6 address space...........................4 2.1.2 Example of IPv6 address usage..........................6 2.2 IPv6 registration issues...................................8 2.3 IPv6 and DNS...............................................8 2.3.1 Forward mapping........................................8 2.3.2 Reverse mapping.......................................10 2.3.3 Implementations.......................................10 2.4 Routing issues in IPv6....................................11 3. Migration tools..............................................11 3.1 Transition strategies.....................................12 3.2 A short characterisation of the different migration tools.13 4. ISP environments.............................................17 4.1 Introducing IPv6 in an ISP environment....................17 4.1.1 Introducing IPv6 in the core network..................17 4.1.2 Introducing IPv6 in the customer access network.......18 4.2 Internet Exchange.........................................18 5. End user environments........................................20 5.1 Introducing IPv6 in an Intranet environment...............20 5.2 Introducing IPv6 with IPv6 capable upstream provider......21 5.3 Introducing IPv6 without IPv6 capable upstream provider...21 5.4 Single host with upstream provider offering IPv6 connectivity..............................................22 5.5 Single host without upstream provider offering IPv6 connectivity..............................................22 6. IPv6 information on the Internet.............................22 7. Security considerations......................................23 References......................................................24 Authors' addresses..............................................26 Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 2] Internet Draft Guide to IPv6 Transition Apr 1999 1. Introduction This document is a guide to the introduction of IPv6 in the current IPv4 based Internet or Intranets. Section 2 outlines the general issues to start IPv6 networking in a predominantly IPv4 world. Things that will be handled here are ways to obtain IPv6 address space, IPv6 registration issues, IPv6 DNS issues and routing issues. In section 3 short descriptions will be given of the different translation and migration tools that translate between IPv6 and IPv4 and/or tunnel IPv6 over IPv4. In sections 4 and 5 we will discuss how IPv6 can be introduced in various typical environments. Environments we distinguish are: ISPs, Internet Exchanges and End User Environments. Emphasis in these sections will be on the use of the various translation and integration tools that are discussed in section 3. In section 6 pointers to IPv6 information on the Internet will be given. This document addresses the use of IPv6 in a unicast environment. Migration of IPv4 to IPv6 multicast environments has not been considered. This document is not intended to describe the complete migration from IPv4 to IPv6 for the whole Internet. It is however an attempt to describe the possibilities that exist today to introduce IPv6 in a predominantly IPv4 environment and have both IPv6 and IPv4 connectivity within the desired scope. 2. General IPv6 implementation issues The transition from IPv4 to IPv6 will probably follow a dual-stack strategy. The transformation of IPv4 hosts to dual-stack host should not require too much effort considering the similarities between the IPv4 and IPv6 protocol. Upgrading routers is slightly more complex. Besides implementing IPv6 for hosts and routers a few other things need to be done before IPv6 actually can be deployed. First of all IPv6 addresses need to be obtained and these IPv6 addresses need to be registered with Internet Registries and in the Domain Name System (DNS). Most sites will get a /48 prefix with 16 bits for subnetting and 64 bits for interface ID addressing. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 3] Internet Draft Guide to IPv6 Transition Apr 1999 0 48 64 127 +---------------------------------+--------+--------------------+ | prefix | subnet | Interface ID | +---------------------------------+--------+--------------------+ In the following sections it is discussed how to obtain aggregatable globally routable IPv6 address space and how to register this address space. Furthermore, in section 2.3 it is discussed how IPv6 hosts can be registered in the DNS. Section 2.4 discusses some IPv6 routing issues. 2.1 IPv6 address assignments Most of the transition mechanisms require dual stack systems and thus globally routable IPv6 addresses as well as globally routable IPv4 addresses. Although sometimes private IPv4 addresses [RFC1918] will suffice. But to allow communication between IPv4 and IPv6 hosts over the Internet at least one globally unique IPv4 address is always needed. Globally unique IPv4 addresses can be obtained from one of the Regional Internet Registries (IR), Local Internet Registries (LIR) or an Internet Service Provider (ISP). Without special registration a site can deploy IPv6 site local addresses which are similar to IPv4 private addresses [RFC1918]. However, site local addresses do not allow for communication over the Internet. For this you need to apply for globally routable IPv6 addresses. At present, there is an experimental network called the "6bone" which is operated based on IPv6. For this network, a part of the aggregatable address space is assigned, the so-called Pseudo TLA (pTLA) 3ffe::/16. Provider pTLAs are assigned by the 6bone [6BONE]. NLAs are assigned in turn by those organisations which have received pTLA assignments from the 6bone. 2.1.1 Obtaining IPv6 address space IPv6 addresses can be obtained from the same organisations as the ones who register IPv4 addresses. Basically regional IRs delegate a part of the IPv6 address space to local IRs who further delegate parts of the address space to their customers. The smallest assignment that can be made to a customer is a /48 prefix. A difference between IPv4 and IPv6 allocations is that one of the main objectives of IPv6 allocation is route aggregation, i.e. to minimise the number of prefixes that need to be advertised in the default-free core of the Internet. The regional IRs use a slow start mechanism [IRALLOC] to allocate TLAs to ISPs. ISPs can be divided into two categories: those ISPs Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 4] Internet Draft Guide to IPv6 Transition Apr 1999 that can get a (sub-)TLA from their regional Internet Registry (IR) and those ISPs that will not get a (sub-)TLA. In this document the first category is referred to as "TLA ISPs" and the second category is referred to as "NLA ISPs", because they will get an NLA from their upstream provider(s). TLA ISPs will get a sub-TLA first and can apply for a full TLA later. This sub-TLA is a /29 prefix. The TLA ISP will allocate /48 prefixes to end customer sites and /(29+n) prefixes to NLA ISPs, in which "n" (0<=n<=19) is the number of bits used to identify NLA ISPs [RFC2374]. +--+----------+---------+---------+--------+--------------------+ | 3| 13 | 13 | 19 | 16 | 64 bits | +--+----------+---------+---------+--------+--------------------+ |FP| TLA | sub-TLA | NLA | SLA | Interface ID | | | ID | | ID | ID | | +--+----------+---------+---------+--------+--------------------+ |<--- TLA ISP prefix -->|<--->|<------ bits for NLA ISP --------> | | NLA ISP identifier (n bits) An NLA ISP will be allocated a prefix between /29 and /48. It will use the remaining bits in the NLA ID to identify its customers. These customers will get a /48. +--+----------+---------+---------+--------+--------------------+ | 3| 13 | 13 | 19 | 16 | 64 bits | +--+----------+---------+---------+--------+--------------------+ |FP| TLA | sub-TLA | NLA | SLA | Interface ID | | | ID | | ID | ID | | +--+----------+---------+---------+--------+--------------------+ |<------ NLA ISP prefix ----->|<->|<------ bits for sites ------> | | end customer site identifier (19-n bits) Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 5] Internet Draft Guide to IPv6 Transition Apr 1999 2.1.2 Example of IPv6 address usage Sites will get a /48. An example of how to use such a /48 is given below. In this example the site is allocated 3FFE:1234:5678::/48. 3FFE:1234:5678::/48 | | Int1 +-----+-----+ Int2 +-------+ R1 +-------------------+ | +---------+-+ | | | Int3 | +-------+-------+ +----+ +-----+----+ | | | | R2 | | | | +----------+ +----+----+ +----+----+ +----+----+ |||||||||| | R3 | | R4 | | R5 | links +---------+ +---------+ +---------+ | | | | | | | | | | links links links R[1-5] are routers and I[1-3] are the interfaces of R1. Suppose the expected number of hosts on the links is: router immediate year 1 year 2 R2 34 50 70 R3 19 20 25 R4 9 10 15 R5 3 5 10 A number plan could be like the one shown in the table below. On R1 the following prefixes will be used on the interfaces: Int1 3FFE:1234:5678:2000::/50 Int2 3FFE:1234:5678:0000::/49 Int3 3FFE:1234:5678:2300::/50 Initially, R2 will get 256 /64s, R3 will get 48 /64s, R4 will get 32 /64s and R5 will get 16 /64s. 3FFE:1234:5678:0000::/50 ------------------------ 3FFE:1234:5678:0000::/49 Int2 3FFE:1234:5678:1000::/49 free 3FFE:1234:5678:2000::/49 Int1 + Int3 3FFE:1234:5678:3000::/49 free ..... 3FFE:1234:5678:F000::/49 free Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 6] Internet Draft Guide to IPv6 Transition Apr 1999 3FFE:1234:5678:0000::/49 ------------------------ 3FFE:1234:5678:0000::/64 interfaces of R2 ..... 3FFE:1234:5678:00FF::/64 interfaces of R2 3FFE:1234:5678:0100::/64 reserved for R2 ..... 3FFE:1234:5678:02FF::/64 reserved for R2 3FFE:1234:5678:0300::/64 free ..... 3FFE:1234:5678:2000::/49 ------------------------ 3FFE:1234:5678:2000::/50 Int1 3FFE:1234:5678:2100::/50 reserved for Int1 3FFE:1234:5678:2200::/50 reserved for Int1 3FFE:1234:5678:2300::/50 Int3 3FFE:1234:5678:2400::/50 reserved for Int3 3FFE:1234:5678:2500::/50 reserved for Int3 3FFE:1234:5678:2600::/50 free ..... 3FFE:1234:5678:2F00::/50 free 3FFE:1234:5678:2000::/50 ------------------------ 3FFE:1234:5678:2000::/64 interfaces of R3 ..... 3FFE:1234:5678:202F::/64 interfaces of R3 3FFE:1234:5678:2030::/64 reserved for R3 ..... 3FFE:1234:5678:204F::/64 reserved for R3 3FFE:1234:5678:2050::/64 interfaces of R4 ..... 3FFE:1234:5678:206F::/64 interfaces of R4 3FFE:1234:5678:2070::/64 reserved for R4 ..... 3FFE:1234:5678:209F::/64 reserved for R4 3FFE:1234:5678:20A0::/64 free ..... 3FFE:1234:5678:20FF::/64 free Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 7] Internet Draft Guide to IPv6 Transition Apr 1999 3FFE:1234:5678:2300::/50 ------------------------ 3FFE:1234:5678:2300::/64 interfaces of R5 ..... 3FFE:1234:5678:230F::/64 interfaces of R5 3FFE:1234:5678:2310::/64 reserved for R5 ..... 3FFE:1234:5678:231F::/64 reserved for R5 3FFE:1234:5678:2320::/64 free ..... 3FFE:1234:5678:23FF::/64 free 2.2 IPv6 registration issues In the current IPv4 world address space allocations are registered in the various databases managed by the regional IRs. Autonomous System (AS) information and routing policies are registered in the distributed Internet Routing Registry database (IRR). The IRs, LIRs and ISPs are supposed to register address space allocations and assignments, contact persons, AS numbers, routing policies and other useful data for network management in the various databases. A special IPv6 registration database has been setup for the 6bone community, on the whois server named "whois.6bone.net". This is a special version of the RIPE database software and it is referred to as the "6bone database". This database has special objects, the "inet6num:" object for assigned IPv6 prefixes, and the "ipv6-site:" object which is used to register specific information about a site connected to the 6bone, such as the configured tunnels and the origin AS. The database can be queried by using the web-based "whois" service at http://www.6bone.net/whois.html. At this time only the 6bone database supports the special IPv6 objects. Currently, there are no database objects to register IPv6 routing policies. When the regional IRs will start allocating (sub-)TLAs the allocated and assigned IPv6 prefixes, routing policies etc. will have to be registered. At this moment it is unclear how exactly IPv6 registrations will be done. 2.3 IPv6 and DNS Applications are not supposed to directly handle IP addresses but should use names. The mapping between host names and IP addresses in the Domain Name System (DNS) is a crucial service on the Internet [RFC1034, RFC1035]. This service is provided by DNS servers, commonly implemented with the BIND software [BIND]. Using an "A resource" record a name can point to an IPv4 address (forward Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 8] Internet Draft Guide to IPv6 Transition Apr 1999 mapping) and using a "PTR resource" record an IPv4 address can be mapped back to a name (reverse mapping). This mechanism cannot easily be extended to support IPv6 addresses. Some enhancements are needed to use DNS with IPv6 addresses [RFC1886]. To support the storage of IPv6 addresses within DNS and to facilitate renumbering currently other extensions are being defined [DNSLOOKUP]. 2.3.1 Forward mapping A host's 128 bit IPv6 address can be stored with an "AAAA resource" record. For example: $ORIGIN ipv6.surfnet.nl. ... zesbot IN AAAA 3FFE:0604:0000:0001:02C0:4FFF:FEC6:9CC7 This is similar to the use of the "A resource" record in IPv4, for example: $ORIGIN ipv6.surfnet.nl. ... zesbot IN A 192.87.110.60 Note that both "A" and "AAAA resource" records are stored in the same DNS data file. If a node has more than one IPv6 address it must have more than one AAAA record. For example: $ORIGIN ipv6.surfnet.nl. ... amsterdam9 IN AAAA 3FFE:0600:8000:0000::0001 IN AAAA 3FFE:0600:8000:0000::0005 IN AAAA 3FFE:0600:8000:0000::0009 IN AAAA 3FFE:0600:8000:0000::000D Currently a new resource record type, "A6", is being defined to map a domain name to an IPv6 address, containing a reference to a "prefix" [DNSLOOKUP]. The aim of the A6 resource record is to facilitate network renumbering and multihoming. Domains employing the A6 record for IPv6 addresses can have automatically generated AAAA records to ease transition. After the A6 resource records are widely deployed it is expected that the AAAA records are no longer needed. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 9] Internet Draft Guide to IPv6 Transition Apr 1999 2.3.2 Reverse mapping IPv4 uses the "in-addr.arpa" domain for the reverse mapping. An IPv4 address is represented as a name in the in-addr.arpa domain by a sequence of bytes, written as decimal digits, separated by dots with the suffix ".in-addr.arpa". The sequence of bytes is encoded in reverse order, i.e. the low-order bytes is encoded first, followed by the next low-order bytes and so on. For IPv6 addresses the special domain "ip6.int" is defined to look up a record given an IPv6 address. The process works exactly the same as with IPv4. Except that an IPv6 address is represented by nibbles, written as hexadecimal digits, separated by dots. For example the IPv6 address 3FFE:0604:0000:0001:02C0:4FFF:FEC6:9CC7 is represented as a name in the ip6.int domain as: 7.c.c.9.6.c.e.f.f.f.f.4.0.c.2.0.1.0.0.0.0.0.0.0.4.0.6.0.e.f.f.3.ip6.int. This name is stored in the a DNS data file as follows (assuming a /64 prefix): $ORIGIN 1.0.0.0.0.0.0.0.4.0.6.0.e.f.f.3.ip6.int. ... 7.c.c.9.6.c.e.f.f.f.f.4.0.c.2.0 IN PTR zesbot.ipv6.surfnet.nl. This can be compared to the reverse mapping of IPv4 addresses. For example the IPv4 address 192.87.110.60 is represented as a name in the in-addr.arpa domain as: 60.110.87.192.in-addr.arpa. This name is stored in a DNS data file as follows: $ORIGIN 110.87.192.in-addr.arpa. ... 60 IN PTR zesbot.ipv6.surfnet.nl. Note that the IPv4 and IPv6 reverse mappings are stored in different DNS data files. 2.3.3 Implementations Most DNS implementations will be able to deal with the reverse mapping as used with IPv6 addresses. However the AAAA resource record is only implemented in recent DNS implementations, like BIND version 8.1 and higher and the DNS server of Windows 2000. At this moment there is no known implementation of the A6 resource record [DNSLOOKUP] or binary labels [BITLBL]. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 10] Internet Draft Guide to IPv6 Transition Apr 1999 Note that although these DNS servers implement extensions to support the use of IPv6 addresses they are not necessarily IPv6 applications themselves. For IPv6 only nodes an IPv6 DNS server is crucial. 2.4 Routing issues in IPv6 To exchange reachability information routing protocols are used. There are two types of routing protocols, the intra-domain (IGP) and inter-domain (EGP) routing protocols. In the IPv4 world commonly used IGPs are RIP, OSPF and IS-IS and the EGP that is used is mostly BGP4. Besides the use of routing protocols static routing can also be used. To use routing protocols in IPv6 networks they should be adjusted to be able to handle IPv6 routing information. At this moment only RIP (RIPng) [RFC2080, RFC2081] and BGP4 (BGP4+) [RFC2283, BGP4-IPV6] implementations with IPv6 extensions are available. The IETF OSPF Working Group [OSPFWG] has defined IPv6 extensions to the OSPF routing protocol. Unfortunately, there are no implementations at this moment. On the 6bone static routing, BGP4+ and RIPng are used. IPv6 routing is very strict in aggregation. Care must be taken what to announce to other ISPs, especially in peerings with other TLA ISPs. ISPs should only announce sub-TLAs and smaller (i.e. at most a /29) to other TLA ISPs. The TLA ISP can decide which (sub-)TLAs it will announce to another TLA ISPs according to its routing policy. The TLA ISP is allowed to announce prefixes larger than a /29 to ISPs and customers that fall inside its own (sub-)TLA. Usually, a /48 is the largest prefix that will be announced. An NLA ISP can be multi-homed to several TLA ISPs. The NLA ISP will get a next level NLA from all of them, but the NLA ISP should not announce these NLAs to all TLA ISPs. The NLA ISP should only announce the NLA that was given by that TLA ISP to that TLA ISP. On the other side, the NLA ISP will announce all NLAs to its customers. For specific information about routing aspects of IPv6 transition see [RFC2185]. 3. Migration tools In this section a short introduction will be given on transition strategies for IPv6 nodes. In section 3.2 short descriptions are listed for the various translation and migration tools that are being developed. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 11] Internet Draft Guide to IPv6 Transition Apr 1999 3.1 Transition strategies Basically there are two different mechanisms to allow IPv6 nodes to maintain compatibility with IPv4 only nodes. - Dual IP stack. Providing complete support for both IPv4 and IPv6 in hosts and routers. - IPv6 over IPv4 tunneling. Encapsulating IPv6 packets within IPv4 headers to carry them over IPv4 routing infrastructures. +-------------------+ +--------+ | application | | IPv6 | +-------------------+ | domain | +--------+ | TCP / UDP | +--------*---* | +-------------------+ | IPv4 | | IPv4 | IPv6 | |networks| +-------------------+ | *---*--------+ | network layer | +--------+ | IPv6 | | | | domain | +-------------------+ +--------+ a. dual stack strategy b. route IPv6 over IPv4 only networks * Dual IP stack Dual stack nodes will be able to interoperate directly with both IPv4 and IPv6 nodes. They must provide resolver libraries capable of dealing with the IPv4 A records as well as the IPv6 AAAA records. When both A and AAAA records are listed in the DNS there are three different options [RFC1933], (i) return only IPv6 address(es), (ii) return only IPv4 address(es) or (iii) return both IPv4 and IPv6 addresses. The selection of which address type to return, or, in which order can affect what type of IP traffic is generated. * Tunneling IPv6 nodes that are only connected through IPv4 networks can build a virtual link by configuring a tunnel. IPv6 packets going towards another IPv6 domain will then be encapsulated within IPv4 packets. The tunnel end-points are two IPv4 addresses. Two types of tunneling can be employed: configured and automatic. Configured tunnels are created by manual configuration. The 6bone itself is an example of a network containing mainly configured tunnels. Automatic tunnels on the other hand do not need manual configuration. The tunnel end-points are automatically determined. For example by using special IPv6 unicast addresses that carry an IPv4 address in the low-order 32-bits, e.g. IPv4-compatible IPv6 Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 12] Internet Draft Guide to IPv6 Transition Apr 1999 addresses [RFC2373] or IPv4-mapped IPv6 addresses [RFC2373]. 3.2 A short characterisation of the different migration tools A short description of the different translation and migration tools is listed below. Note that the mentioned "applicability scope" shows if the tool is intended to be used for an entire site or is to be implemented on a single host. Listed is further if there are any general IPv4 related requirements, IPv4 address requirements, specific IPv6 requirements, IPv6 address requirements or other requirements. * [6TO4]: Applicability scope: site IPv4 requirements: need IPv4 inter connectivity between sites IPv4 address requirements: >= 1 per site IPv6 requirements: global unique 6to4 prefix (624TLA) IPv6 address requirements: none Host requirements: IPv6 stack Router requirements: implementation of special forwarding and decapsulation rules Other requirements: creation of specific DNS record that reflects 6TO4 prefix and "IPv4" address NLA Description: The [6TO4] tool is applicable for interconnection of isolated IPv6 domains in an IPv4 world. The egress router of the IPv6 domain creates a tunnel to the other domain. The IPv4 endpoints of the tunnel are identified in the prefix of the IPv6 domain. This prefix is made up of a unique 6TO4 TLA plus an NLA that identifies the site by the IPv4 address of the translating egress router. * [6OVER4]: Applicability scope: host IPv4 requirements: IPv4 multicast inter connectivity between hosts IPv4 address requirements: 1 per host IPv6 requirements: none IPv6 address requirements: none Host requirements: IPv4/IPv6 stack Router requirements: 6OVER4 configuration to route between different virtual links and/or virtual links and the IPv6 Internet Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 13] Internet Draft Guide to IPv6 Transition Apr 1999 Other requirements: To connect IPv6 hosts on different physical links, IPv4 Multicast routing must be enabled on the routers connecting the links Description: Interconnection of isolated IPv6 hosts in a site is realised through IPv6 in IPv4 encapsulation. A virtual link is created using an IPv4 multicast group with organisational local scope. IPv6 multicast addresses are mapped to IPv4 multicast addresses to be able to do Neighbour Discovery. To route between the IPv6 Internet and the 6OVER4 domain in an organisation, a router needs to be configured as 6OVER4 on at least one interface. * [NAT-PT]: Applicability scope: site IPv4 requirements: none IPv4 address requirements: >=1 per site IPv6 requirements: none IPv6 address requirements: none Host requirements: IPv6 stack Router requirements: none, but the router might be the NAT-PT device Other requirements: none Description: [NAT-PT] address the communication between IPv6 only and IPv4 only hosts. The communication is realised by use of a dedicated device that does the translation between IPv4 and IPv6 addresses and keeps state during the time of the session. The NAT-PT device also includes an application layer gateway to make translation possible between IPv4 and IPv6 DNS requests and answers. * [SIIT]: Applicability scope: site IPv4 requirements: none IPv4 address requirements: 1 temporary per IPv6 host IPv6 requirements: none IPv6 address requirements: IPv4-mapped and IPv4-translated addresses to identify IPv4 nodes and IPv6 capable nodes respectively Host requirements: IPv6 stack Router requirements: none Other requirements: none Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 14] Internet Draft Guide to IPv6 Transition Apr 1999 Description: The protocol describes a method to translate between IPv6 and IPv4. Translation is limited to the IP packet header. The work does not describe a method to assign a temporary IPv4 address to the IPv6 node. The translator is operating in a stateless mode, which means that translation needs to be done for every packet. * [AIIH]: Applicability scope: site IPv4 requirements: none specific IPv4 address requirements: >= 1 per site IPv6 requirements: DHCPv6 extensions [DHCPv6-EXT] IPv6 address requirements: none Host requirements: IPv4/IPv6 stack Router requirements: none Other requirements: none Description: AIIH is based on cooperation between DNS and DHCPv6 [DHCPv6]. The main idea is that when an IPv4/IPv6 host wants to communicate with an IPv4 only host, it requests for the duration of the communication a temporary IPv4 address. If an IPv4 host wants to communicate with an IPv4/IPv6 host, the DNS server sends back an A record for the host and co-located DHCPv6 server (that is co-located with the DNS server) sends a reconfigure command to the dual stack host to assign a temporary IPv4 address. * [SOCKS64]: Applicability scope: site IPv4 requirements: none specific IPv4 address requirements: 1 per host IPv6 requirements: >= 1 per site IPv6 address requirements: none Host requirements: clients should be "socksified" Router requirements: none Other requirements: dual stack SOCKS server Description: The [SOCKS64] tool is a gateway system that accepts [SOCKSv5] connections from IPv4 hosts and relays it to IPv4 or IPv6 hosts. Especially for "socksified" sites, who already use SOCKS aware clients and a SOCKS server, SOCKS64 provides an easy way to let IPv4 hosts connect to IPv6 hosts. No DNS modifications or address mapping is needed. The principle can also be used to allow IPv6 Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 15] Internet Draft Guide to IPv6 Transition Apr 1999 hosts to connect to IPv4 hosts, IPv4 hosts over IPv6 networks and IPv6 hosts over IPv4 networks [SOCKS-TRANS]. The later cases resemble tunnel techniques without possible problems with fragmentation or hop limits. * [BITSv6]: Applicability scope: host IPv4 requirements: none IPv4 address requirements: pool of private address space per host IPv6 requirements: none IPv6 address requirements: none Host requirements: IPv6/IPv4 stack plus extensions Router requirements: none Other requirements: none Description: The model allows for the use of none IPv6 capable applications on a dual stack host to communicate with IPv6 only hosts. Added to the IPv4/IPv6 dual stack are three modules that intervene between the application and the network, an extension to the name resolver, an address mapper and a translator. The main idea is that when an IPv4 application needs to communicate with an IPv6 only host, the IPv6 address of that host is mapped into an IPv4 address out of a pool local to the dual stack hosts. The IPv4 packet generated for the communication is translated into an IPv6 packet according to SIIT. * [TunnelBroker]: Applicability scope: host IPv4 requirements: none IPv4 address requirements: 1 IPv6 requirements: none IPv6 address requirements: none Host requirements: IPv4/IPv6 stack, IPv4 Web browser Router requirements: none Other requirements: Tunnel Broker server Description: The tunnel broker is a web based tool that allows interactive setup of an IPv6 over IPv4 tunnel. By requesting a tunnel, the host gets assigned an IPv6 address out of the address space of the tunnel provider. DNS will be updated automatically. The created tunnel will provide IPv6 connectivity between the tunnel provider's IPv6 environment and the isolated host. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 16] Internet Draft Guide to IPv6 Transition Apr 1999 4. ISP environments This section describes how different organisations (ISPs, Internet Exchanges) can start deploying IPv6. It describes how IPv6 can be setup in the organisation and how to connect to the global IPv6 infrastructure. 4.1 Introducing IPv6 in an ISP environment The network of an ISP consists of at least three main areas: the core network, the connections to other IPSs and the customer access network. The next two sections will discuss how an ISP can introduce IPv6 in those areas. For each area a couple of steps must be taken first: * Request IPv6 address space as described in section 2.1. * Register the IPv6 site, routing and delegations as described in section 2.2. * Setup DNS as described in section 2.3. 4.1.1 Introducing IPv6 in the core network It is not really necessary to introduce IPv6 into the core of the network. An ISP may decide to tunnel IPv6 over its existing IPv4 infrastructure. But if the ISP decides to introduce IPv6 into the core, this can be done in several ways. An ISP might decide to install separate dual stack or IPv6-only routers in the core. These will be interconnected by dedicated lines (ATM PVCs, leased lines, etc.) or (if the routers are dual stack) by IPv6 in IPv4 tunnels over the existing IPv4 core infrastructure. Routing can be setup such that IPv4 packets are routed through the old IPv4 infrastructure and IPv6 packets are routed through the new IPv6 infrastructure. When dual stack routers are stable enough to be used in the core, things become simpler. The ISP can configure the core routers as dual stack routers which will route both IPv4 and IPv6 packets. Next a connection to the global IPv6 network should be made. This can be done by a direct IPv6 connection or by some tunneling mechanism. If the core of the network supports IPv6 and the other ISP also supports IPv6 a direct link can be used to transport IPv6 packets. When there is no direct IPv6 connection tunneling mechanisms must be used to reach the global IPv6 network. Automatic tunneling can be done with for example [6TO4]. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 17] Internet Draft Guide to IPv6 Transition Apr 1999 An ISP might decide to setup one or more routers at the edge of its network to act as 6to4 gateways. This enables other IPv6 islands to reach the ISP by 6to4 tunneling. An alternative to the use of dynamic tunnels is the use of static ones as is the case on the 6Bone. 4.1.2 Introducing IPv6 in the customer access network The customer access network consists of dial up and leased lines connected to an access router. There are at least two possibilities to introduce IPv6. The first possibility is to upgrade access routers to dual stack routers. Both IPv4 and IPv6 customers connect to these dual stack routers. Another possibility is to install separate IPv6 or dual stack routers. IPv4-only customers connect to the old IPv4-only access routers. IPv6 customers connect to the new access routers. These IPv6 access routers must be connected to the global IPv6 network. If the core does not support IPv6, one of the transition mechanisms from section 3 must be used. Automatic tunneling can be done with for example [6TO4]. An alternative to the use of dynamic tunnels is the use of statically configured ones. When the core network does support IPv6 the access routers can be connected to the nearest IPv6 core router (either by IPv4/IPv6 link, dedicated link or tunneling over IPv4). When the customer is an IPv6-only site, the ISP might decide to provide some transition mechanisms to help the customer reach IPv4-only nodes. To do this the ISP can install e.g. NAT-PT (see section 5.3). 4.2 Internet Exchange Based on address space distribution we can distinguish two models for the setup of an IPv6 Internet Exchange (IE). 1. The more or less traditional model that is most common in the IPv4 world. In this case each ISP connecting to the IE arranges its own IPv6 address space. In peering arrangements between ISPs the prefix for this address space is exchanged. 2. An addressing model where the IE acts as an address space provider. In this case the IE obtains a TLA and can assign NLAs from this TLA address space to connected ISPs. In order to obtain global connectivity for the Internet Exchange TLA, the IE needs to arrange for global transit through one or more global transit Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 18] Internet Draft Guide to IPv6 Transition Apr 1999 providers (TLA ISPs) which are connected to the IE. Implicitly, this means that the IE arranges transit for all connected ISPs that use the address space assigned to the IE. This requires quite a different business model for an IE than in model 1. Models 1 and 2 described above require the following steps to be taken by the IE operator and/or the connected ISPs: * Model 1: - IE operator requests an NLA Obtain globally unique address space. This can be an NLA from a transit provider (TLA provider) that offers connectivity for the IE infrastructure. A global prefix is preferred as next hop attribute in BGP4 [BGP4-IPV6]. - Addressing infrastructure on IE From the obtained address space addresses are assigned to the interfaces of the routers connecting to the IE infrastructure. - Update the IPv6 registry The sites, allocations and route objects should be registered as described in section 2. - BGP announcements ISPs connecting to the IE advertise to their peers their own address space which is independent of the IE. This address space can either be a TLA or an NLA. * Model 2: - IE operator requests a (sub-)TLA The IE requests a (sub-)TLA from its regional IR. Customers on the Internet Exchange get a next level NLA from this (sub-)TLA. - Addressing infrastructure on IE From the obtained address space addresses are assigned to the interfaces of the routers connecting to the IE infrastructure. - Update the IPv6 registry The sites, allocations and route objects should be registered as described in section 2. - IE operator contracts global transit ISPs (TLA ISPs) The IE should contract several TLA ISPs that will provide connectivity to the global IPv6 network. Such a TLA ISP must agree to transit traffic from all customers connected to the IE. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 19] Internet Draft Guide to IPv6 Transition Apr 1999 - BGP announcements The transit providers for the IE address space announce the (sub-)TLA from the IE to the global IPv6 network. To the IE customers they announce all prefixes that can be reached by them and for which they have a contract with the IE. Customers (NLA ISPs) get a next level NLA from the IE. The NLA ISPs announce their NLA to the TLA ISPs. They also announce their NLA to other NLA ISPs of the IE if there is a peering agreement between them. 5. End user environments This section describes how end users can start deploying IPv6 in their networks. We define an end user environment as a network consisting of a single routing domain that is not being used to offer Internet access to others. In the extreme case an end user can be only one host that dials in to an ISP. For the cases of end users we can distinguish two main situations, one where the Internet provider for the end host offers IPv6 connectivity and the other where the Internet provider does not offer IPv6 connectivity. Next to this distinction the situation is different for a single dial-in host or for a network. Last we can distinguish the case where the end user is an Intranet that is not connected to the Internet. The general expectation is that the introduction of IPv6 in the Internet will happen with dual stack hosts and routers. However, for a very long time (one might consider decades) there will remain IPv4 only applications, servers and end stations. Also, one might expect the introduction of IPv6 only stacks in devices that up till now do not run on IP, for example GSM telephones, PDAs and home devices. To make inter-operability possible between the IPv6 and the IPv4 world a number of tools are available. The sections below discuss the different end user situations described above and the possibilities to introduce IPv6 in that particular environment. 5.1 Introducing IPv6 in an Intranet environment Methods to introduce IPv6 in an Intranet environment depend very much on the scale and topology of the Intranet. Assumed is that there is no IPv4 addressing issue in the Intranet. We distinguish the following situations: * A number of isolated IPv4/IPv6 dual stack hosts. - In case the hosts all reside on the same link there is no issue. - In case the IPv6/IPv4 hosts reside on different links there are several options for IPv6 communication between these hosts: Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 20] Internet Draft Guide to IPv6 Transition Apr 1999 - IPv6 routing is turned on on the routers connecting the links. - if IPv4 multicast routing is enabled between the links, [6OVER4] can be used to create virtual links. * A number of isolated IPv6 capable networks can be distinguished in the Intranet. - For IPv6 communication between these networks the following could be applied : - turn on routing on the routers interconnecting the networks. - implement [6TO4] on the egress routers connecting the networks to the Intranet. In all cases it might be useful to implement [BITSv6] to make it possible for IPv4 only applications to communicate in the IPv6 world. 5.2 Introducing IPv6 with IPv6 capable upstream provider To introduce IPv6 in end user networks where the upstream provider is offering both IPv4 and IPv6 connectivity the implementation issues are actually the same as in the Intranet environment described in the previous section. The end user network must be made capable of routing IPv6. The upstream provider for Internet connectivity will take care of routing to both the IPv4 and the IPv6 world. 5.3 Introducing IPv6 without IPv6 capable upstream provider To introduce IPv6 in an end user network if the upstream provider is not offering IPv6 connectivity there are two possible approaches. To implement connectivity for the end user network to the IPv6 world one can either use [6TO4] or a statically configured tunnel from the end user network egress router to an IPv6 provider. Once there is IPv6 connectivity between the end user network and the IPv6 world we can have the following situations: * IPv4/IPv6 hosts - General availability of IPv4 addresses: in this situation there is no issue. - Limited availability of IPv4 addresses: in this case we have no problems to communicate from the host at the end user network to an IPv6 capable host in the rest of the world. In order to communicate with the IPv4 world, assignment of a temporary IPv4 address to a host is necessary. This can be accomplished with [AIIH]. * IPv6 only hosts - If there are IPv6 only hosts on the end user network then Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 21] Internet Draft Guide to IPv6 Transition Apr 1999 [NAT-PT] offers a solution to communicate with the IPv4 world. In all cases it might be useful to implement [BITSv6] to make it possible for IPv4 only applications to communicate in the IPv6 world. 5.4 Single host with upstream provider offering IPv6 connectivity This situation typically applies in the case of a dial-in user connecting to a dial-in provider. We assume the provider takes full responsibility to reach both the IPv4 and the IPv6 world at the network level and the dial-in user should not be concerned with this. We can distinguish the following situations: * If the dial-in host gets assigned both an IPv6 and IPv4 address: full connectivity between both the IPv6 and IPv4 world is possible. * The dial-in user only gets assigned an IPv6 address: in case connectivity with an IPv4 hosts is necessary, the ISP might typically offer interconnectivity services like [AIIH], [SIIT] or [NAT-PT]. The host might consider implementing [BITSv6] to use IPv4 only applications to communicate with IPv6 servers. 5.5 Single host without upstream provider offering IPv6 connectivity This situation typically applies to dial-in users connecting to a dial-in provider with no IPv6 support or to isolated IPv6 users or testers in an pure IPv4 environment. In case of a dual stack host the typical solution for this situation is use of the web based [TunnelBroker] application to obtain connectivity to the IPv6 world. The use of the [BITSv6] implementation can be considered for the use of communicating between IPv4 only applications on the local host and IPv6 only servers. 6. IPv6 information on the Internet On various places on the Internet information can be obtained on IPv6 implementations, deployment and transitioning. Some good starting points are listen below. * http://playground.sun.com/pub/ipng/html/ Provides general information about the Next Generation Internet Protocol (IPng). Also contains pointers to other IPv6 resources. * http://www.6bone.net Source of information about the 6bone, a virtual network layered on top of portions of the physical IPv4-based Internet used as a testbed for IPv6 connectivity and interoperability. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 22] Internet Draft Guide to IPv6 Transition Apr 1999 Also contains pointers to other IPv6 resources. * http://www.6ren.net Source of information about the 6ren, an initiative that wants to provide production IPv6 transit service to facilitiate high quality, high performance, and operationally robust IPv6 networks. Also contains pointers to other IPv6 resources. * http://www.ipv6.org Contains many pointers to various IPv6 resources. 7. Security considerations There are no specific security issues introduced by this document. For the specific security issues with the different translations and migration tools that are discussed in section 3 of this document the reader is referred to the referenced documents. Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 23] Internet Draft Guide to IPv6 Transition Apr 1999 References [6BONE] http://www.6bone.net. [6OVER4] B. Carpenter, C. Jung, "Transmission of IPv6 over IPv4 Domains without Explicit Tunnels", draft-ietf-ipngwg-6over4-02.txt (work in progress). [6TO4] B. Carpenter, K Moore, "Connection of IPv6 Domains via IPv4 Clouds without Explicit Tunnels", draft-ietf-ngtrans-6to4-01.txt (work in progress). [AIIH] Jim Bound, "Assignment of IPv4 Global Addresses to IPv6 Hosts (AIIH)", draft-ietf-ngtrans-assgn-ipv4-addrs-01.txt (work in progress). [BGP4-IPV6] Pedro R. Marques and Francis Dupont, "Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing", draft-ietf-idr-bgp4-ipv6-02.txt, (work in progress). [BITLBL] Matt Crawford, "Binary Labels in the Domain Name System", draft-ietf-dnsind-binary-labels-04.txt (work in progress). [BITSv6] K. Tsuchiya, H. Higuchi, Y. Atarashi, "Dual Stack Hosts using the Bump-in-the-Stack technique", draft-ietf-ngtrans-dual-stack-hosts-00.txt (work in progress). [DHCPv6] J. Bound, C. Perkins, "Dynamic Host Configuration Protocol for IPv6", draft-ietf-dhc-dhcpv6-14.txt (work in progress). [DHCPv6-EXT] C. Perkins, J. Bound, "Extensions for the Dynamic Host Configuration Protocol for IPv6", draft-ietf-dhc-v6exts-11.txt (work in progress). [DNAME] Matt Crawford, "Non-Terminal DNS Name Redirection", draft-ietf-dnsind-dname-03.txt (work in progress). [DNSLOOKUP] Matt Crawford, Christian Huitema, Susan Thomson, "DNS Extensions to Support IP Version 6", draft-ietf-ipngwg-aaaa-03.txt (work in progress). [IRALLOC] Regional IRs, "IPv6 assignment and allocation policy document (5th draft)", ipv6policy-draft-160499.txt (work in progress). Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 24] Internet Draft Guide to IPv6 Transition Apr 1999 [NAT-PT] George Tsirtsis, Pyda Srishuresh, "Network Address Translation - Protocol Translation (NAT-PT)", draft-ietf-ngtrans-natpt-05.txt (work in progress). [OSPFWG] http://www.ietf.org/html.charters/ospf-charter.html. [RFC1034] P. Mockapetris, "Domain names - concepts and facilities", RFC 1034, November 1987. [RFC1035] P. Mockapetris, "Domain names - implementation and specification", RFC 1035, November 1987. [RFC1886] S. Thomson and C. Huitema, "DNS Extensions to support IP version 6", RFC 1886, December 1995. [RFC1918] Y. Rekhter, B. Moskowitz, D. Karrenberg, G. J. de Groot and E. Lear, "Address Allocation for Private Internets", RFC 1918, February 1996. [RFC1933] R. Gilligan and E. Nordmark, "Transition Mechanisms for IPv6 Hosts and Routers", RFC 1933, April 1996. [RFC2080] G. Malkin, R. Minnear, "RIPng for IPv6", RFC 2080, January 1997. [RFC2081] G. Malkin, "RIPng Protocol Applicability Statement", RFC 2081, January 1997. [RFC2185] R. Callon, D. Haskin, "Routing Aspects of IPv6 Transition", RFC 2185, September 1997. [RFC2283] T. Bates, R. Chandra, D.Katz, Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 2283, February 1998. [RFC2373] R. Hinden, S. Deering, "IP Version 6 Addressing Architecture", RFC 2373, July 1998. [RFC2374] R. Hinden, M. O'Dell, S. Deering, "An IPv6 Aggregatable Global Unicast Address Format", RFC 2374, July 1998. [SIIT] Erik Nordmark, "Stateless IP/ICMP Translator", draft-ietf-ngtrans-siit-05.txt (work in progress). [SOCKS64] A. Jinzaki and S. Kobayashi, "SOCKS64: An IPv4-IPv6 intercommunication gateway using SOCKS5 protocol", draft-jinzaki-socks64-00.txt (work in progress). [SOCKS-TRANS] H. Kitamura, "A SOCKS-based IPv6/IPv4 Translator Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 25] Internet Draft Guide to IPv6 Transition Apr 1999 Architecture", draft-kitamura-socks-ipv6-trans-arch-00.txt (work in progress). [SOCKSv5] M. Leech, M. Ganis, Y. Lee, R. Kuris, D. Koblas and L. Jones, "SOCKS Protocol Version 5", RFC 1928, March 1996. [TunnelBroker] http://www.freenet6.net/. Authors' Addresses Wim Biemolt SURFnet ExpertiseCentrum bv P.O. Box 19115 3501 DC Utrecht The Netherlands Phone: +31 30 230 5305 Fax: +31 30 230 5329 E-mail: Wim.Biemolt@sec.nl Marijke Kaat SURFnet ExpertiseCentrum bv P.O. Box 19115 3501 DC Utrecht The Netherlands Phone: +31 30 230 5305 Fax: +31 30 230 5329 E-mail: Marijke.Kaat@sec.nl Ronald van der Pol SURFnet bv P.O. Box 19035 3501 DA Utrecht The Netherlands Phone: +31 30 230 5305 Fax: +31 30 230 5329 E-mail: Ronald.vanderPol@surfnet.nl Henk Steenman AT&T, ICoE Laarderhoogtweg 25 1101 EB Amsterdam The Netherlands Phone: +31 20 409 7656 Fax: +31 20 453 1574 E-mail: Henk.Steenman@icoe.att.com Biemolt, Kaat, van der Pol, Steenman Expires October 1999 [page 26]