INTERNET-DRAFT W. Biemolt, SEC NGTRANS WG M. Kaat, SEC October 1999 T. Larder 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 IPv4 based Internet or Intranets. Several general issues to start IPv6 networking in a predominantly IPv4 world are discussed, such as IPv6 addresses, IPv6 DNS and routing issues. Short descriptions are given of the different translation and migration tools and mechanisms that translate between IPv6 and IPv4 and/or tunnel IPv6 over IPv4. The remainder of this document describes how IPv6 can be introduced in various environments, such as ISPs, Internet Exchanges and end user environments. Suggestions are given on the use of the different translation and migration tools in each environment. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 1] Internet Draft Guide to IPv6 Transition Oct 1999 Table of Contents Status of this Memo..............................................1 1. Introduction .................................................3 2. General IPv6 deployment issues................................3 2.1 IPv6 addressing ...........................................4 2.2 IPv6 and DNS...............................................4 2.3 Routing in IPv6............................................4 3. Basic Migration tools.........................................5 3.1 Dual Stack and Tunneling - Overlay IPv6....................5 3.2 Protocol Translation.......................................6 4. The Tools In System Solutions.................................7 4.1 Configured and Automatic Tunnels...........................7 4.2 6TO4.......................................................8 4.3 6OVER4.....................................................8 4.4 DSTM.......................................................9 4.5 SIIT.......................................................9 4.6 NAT-PT....................................................10 4.7 BITSv6....................................................10 4.8 SOCKS64...................................................10 5. Case Studies, categorization.................................11 5.1 Large organization with a lot of global IPv4 addresses....11 5.2 Large organization with few global IPv4 addresses.........12 5.3 Office or home network with one global ipv4 address.......12 5.4 New network with brand new services.......................13 5.5 ISP case..................................................13 5.6 Internet Exchange.........................................14 6. Case studies, examples.......................................15 6.1 Isolated IPv6 host in an IPv4 Domain......................15 6.2 Small/Medium Organization using a NAT.....................18 6.3 Introducing IPv6 in an ISP environment....................23 6.4 Internet Exchange.........................................25 7. Security considerations......................................27 References......................................................27 Authors' addresses..............................................29 Appendix A - Example of IPv6 address usage......................30 A.1 Ipv6 Address Assignments.................................30 A.2 Ipv6 Registration Issues.................................32 A.3 Example of IPv6 address usage............................32 Appendix B - Example of IPv6 address usage......................35 B.1 Forward mapping..........................................35 B.2 Reverse mapping..........................................35 B.3 Implementations..........................................36 Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 2] Internet Draft Guide to IPv6 Transition Oct 1999 1. Introduction This document is a guide to the introduction of IPv6 in the current IPv4 based Internet or Intranets. Section 2 shortly introduces some aspects concerning the introduction of IPv6 like addressing, DNS and routing. Addressing and DNS issues are more extensively discussed in the Appendices A and B respectively. In sections 3 and 4 short descriptions will be given of the different translation and migration tools and mechanisms that translate between IPv6 and IPv4 and/or tunnel IPv6 over IPv4. In sections 5 and 6 we will discuss how IPv6 can be introduced in various typical environments. An overview is presented in chapter 5 where environments are categorized and the applicability of the different tools are discussed. In chapter 6 some examples of "real live" environments are presented. 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 to introduce IPv6 in a predominantly IPv4 environment and have both IPv6 and IPv4 connectivity within the desired scope. 2. General IPv6 deployment issues The implementation of an IPv6 network is comparable to the implementation of an IPv4 network. In both cases address space needs to be obtained and the Domain Name System (DNS) and routing should be set up correctly. In Appendix A it is discussed how to obtain aggregatable globally routable IPv6 address space [RFC2374] and how to register this address space. Furthermore, it is discussed how IPv6 hosts can be registered in the DNS. Section 2.3 discusses some IPv6 routing issues. The transition from current IPv4 hosts will most probably follow a dual stack strategy. It is also foreseen however that new devices might be introduced on the network as IPv6 only hosts. Besides upgrading hosts and routers to IPv6 a few other issues need to be addressed like addressing, DNS and routing. These are shortly discussed in the following paragraph. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 3] Internet Draft Guide to IPv6 Transition Oct 1999 2.1 IPv6 addressing Some general information concerning IPv6 addressing is discussed in Appendix A. 2.2 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 record a name can point to an IPv4 address (forward mapping) and using a PTR 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]. A more extensive discussion on IPv6 and DNS is presented in Appendix B. 2.3 Routing 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 only a few implementations available at this moment [ZEBRA] [TELEBIT]. 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 Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 4] Internet Draft Guide to IPv6 Transition Oct 1999 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] and for 6bone routing practice see [RFC2546]. 3. Basic Migration Tools The main concern with the introduction of IPv6 in the current Internet is the need for IPv6 devices to be able to the existing IPv4 world. The (migration) tools that can help in accomplishing this are divided in two broad categories: - Dual Stack and Tunneling - Translation With the first approach the basic idea is that a host or device has two stacks implemented, one for IPv4 and one for IPv6. Each respective stack is used to communicate with other devices equipped with the same IP stack. Tunneling is added to this approach to facilitate the possibility to have two IPv6 (or IPv4) hosts communicating with each other separated by an infrastructure of the other version. The Translation category of tools solves the communication problem by translating the IPv6 packets into an IPv4 packet (and vise versa) while preserving as much as possible the information contained in the packet headers. 3.1 Dual Stack and Tunneling - Overlay IPv6 - 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. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 5] Internet Draft Guide to IPv6 Transition Oct 1999 +-------------------+ +--------+ | application | | IPv6 | +-------------------+ | domain | +--------+ | TCP / UDP | +--------*---* | +-------------------+ | IPv4 | | IPv4 | IPv6 | |networks| +-------------------+ | *---*--------+ | network layer | +--------+ | IPv6 | | | | domain | +-------------------+ +--------+ a. dual stack strategy b. route IPv6 over IPv4 only networks 3.1.1 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. 3.1.2 Tunneling IPv6 nodes (or networks) that are separate by IPv4 infrastructures 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 addresses [RFC2373] or IPv4-mapped IPv6 addresses [RFC2373]. 3.2 Protocol Translation Typically this a solution used to create the possibility to have IPv6 only hosts communicate with the IPv4 world. Typically a protocol translator maps the fields in the packets header of one of the protocols to semantically similar fields in the packet header of the other protocol. A set of rules for the translation between IPv4 and IPv6 is defined in the SIIT [SIIT] proposal further discussed below. It should be noted in IPv4 applications it is not uncommon that the application has knowledge of information from the network Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 6] Internet Draft Guide to IPv6 Transition Oct 1999 layer (like address length or addresses itself). An example of this is FTP. This makes it necessary not only to translate the network layer packets but also translate at the application layer. 4. The Tools In System Solutions 4.1 Configured And Automatic Tunnels 4.1.1 Configured tunnels Manually configured tunnels can be used to connect IPv6 hosts or networks over an IPv4 infrastructure. Typically configured tunnels are used between sites where traffic will be exchanged regularly. Applicability scope: site IPv4 requirements: IPv4 inter connectivity between sites IPv4 address requirements: >= 1 per site IPv6 requirements: none IPv6 address requirements: none specific Host requirements: IPv6 stack or IPv4/IPv6 stack Router requirements: IPv4/IPv6 stack Other requirements: none 4.1.2 Automatic tunnels Automatic tunnels are used as configured tunnels to connect separated IPv6 hosts or networks. Automatic tunnels are created when needed and broken up when no longer necessary. Typically Automatic tunnels are used between individual hosts or between networks where only incidentally there is a need for traffic exchange. A pre-requisite for the use of Automatic tunnels is the existence of IPv4 compatible addresses for the IPv6 hosts that need intercommunication. These addresses allow the hosts to derive the IPv4 addresses of the tunnel endpoints from the IPv6 addresses. Applicability scope: host IPv4 requirements: IPv4 interconnectivity between sites IPv4 address requirements: >= 1 per site IPv6 requirements: none IPv6 address requirements: IPv4 compatible addresses Host requirements: IPv4/IPv6 stack Router requirements: none Other requirements: none 4.1.3 Tunnel Broker The tunnel server [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 Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 7] Internet Draft Guide to IPv6 Transition Oct 1999 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. Currently several implementations of tunnel servers exist [FREENET6], [CSELT]. Applicability scope: host IPv4 requirements: none specific 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 server 4.2 6TO4 The 6to4 [6TO4] tool is applicable for the 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. Applicability scope: site IPv4 requirements: IPv4 interconnectivity between sites IPv4 address requirements: >= 1 per site IPv6 requirements: globally unique 6to4 prefix (TLA624) IPv6 address requirements: none Host requirements: IPv6 stack Router requirements: implementation of special forwarding and decapsulation rules Other requirements: creation of DNS record that reflects 6TO4 prefix and "IPv4" address NLA 4.3 6OVER4 6over4 [RFC2529] interconnects isolated IPv6 hosts in a site through IPv6 in IPv4 encapsulation without explicit tunnels. A virtual link is created using an IPv4 multicast group with organizational local scope. IPv6 multicast addresses are mapped to IPv4 multicast addresses to be able to do Neighbor Discovery. To route between the IPv6 Internet and the 6over4 domain in an organization, a router needs to be configured as 6over4 on at least one interface. Applicability scope: host IPv4 requirements: IPv4 multicast connectivity between hosts IPv4 address requirements: 1 per host IPv6 requirements: none Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 8] Internet Draft Guide to IPv6 Transition Oct 1999 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 Other requirements: To connect IPv6 hosts on different physical links, IPv4 Multicast routing must be enabled on the routers connecting the links 4.4 DSTM Dual Stack Transition Mechanism [DSTM] is a combination of two mechanisms, Assignment of IPv4 Global Addresses to IPv6 hosts (AIIH) and Dynamic Tunneling Interface (DTI). 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 DHCPv6 server sends a reconfigure command to the dual stack host to assign a temporary IPv4 address. The DTI is a virtual interface on the host which takes care encapsulating the IPv4 packets into IPv6 packets. 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 4.5 SIIT The [SIIT] 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. 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 Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 9] Internet Draft Guide to IPv6 Transition Oct 1999 Router requirements: none Other requirements: none 4.6 NAT-PT [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. 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 4.7 BITSv6 The Bump-In-The-Stack [BITSv6] 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. Applicability scope: host IPv4 requirements: none specific 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 4.8 SOCKS64 The SOCKS Gateway [SOCKS-GATE] tool is a gateway system that accepts enhanced [SOCKS-EXT] SOCKS [RFC1928] connections from IPv4 hosts and relays it to IPv4 or IPv6 hosts. Especially for "socksified" Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 10] Internet Draft Guide to IPv6 Transition Oct 1999 sites, who already use SOCKS aware clients and a SOCKS server, SOCKS Gateway 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 hosts to connect to IPv4 hosts, IPv4 hosts over IPv6 networks and IPv6 hosts over IPv4 networks. The later cases resemble tunnel techniques without possible problems with fragmentation or hop limits. 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 5. Case Studies, categorization 5.1 Large organization with a lot of global IPv4 addresses 5.1.1 Description - large organization - multiple sites - No shortage of IPv4 address space, i.e. every host in the organization has Global Iv4 address. - not possible to migrate at once - introduction of IPv6 will be in islands in IPv4 ocean 5.1.2 Possible transition mechanism(s) 5.1.2.1 Internal communication - Dual Stack/Tunneling - 6over4 if a multicast environment is available - Translation is only necessary if islands of IPv6 only devices are created 5.1.2.2 External communication In case the provider does not supply IPv6 connectivity, for connectivity with other IPv6 domains use: - Configured Tunnels - Automatic tunnels (6TO4) For connectivity with the IPv4 world use the existing set-up. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 11] Internet Draft Guide to IPv6 Transition Oct 1999 5.2 Large organization with few global IPv4 addresses (a /24 or less) 5.2.1 Description - large organization - multiple sites - IPv4 address space used on the Intranet is from the private ranges - not possible to migrate at once - introduction of IPv6 will be in islands in IPv4 ocean - NAT between organization network and commodity Internet 5.2.2 Possible transition mechanism(s) 5.2.2.1 Internal communication In essence this is the same situation is in the previous case, but now all hosts use private address space for internal communication over IPv4. - Dual Stack/Tunneling - 6over4 if a multicast environment is available - Translation is only necessary if islands of IPv6 only devices are created within the organization 5.2.2.2 External communication In case the provider does not supply IPv6 connectivity. For connectivity with other IPv6 domains: - Configured or automatic (6TO4) tunnels originating on dual stack routers that have at least one globally unique IPv4 address For connectivity with the IPv4 world: - Use the existing NAT box - Use DSTM to temporarily assign a globally unique IP address to the host. If IPv6 only devices are introduced in the organization a translator mechanism should be added for these devices to talk to the IPv4 world - Implement NAT-PT (or similar) 5.3 Office or home network with ONE global ipv4 address 5.3.1 Description Small amount of hosts One network segment One IPv4 address typically Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 12] Internet Draft Guide to IPv6 Transition Oct 1999 assigned to NAT capable device. 5.3.2 Possible transition mechanism(s) Upgrade to Dual Stack those devices that need communicate with the outside world. No need to assign IPv4 addresses on these. 5.3.2.1 Internal communication - IPv6 - IPv4 using private address space 5.3.2.2 External communication For connectivity to IPv6 world: - IPv6 if upstream provider is IPv6 capable - Dynamic tunnels (6TO4) from egress router - Configured tunnel to IPv6 capable provider For connectivity to IPv4 world: - NAT-PT 5.4 New network with brand new services 5.4.1 Description [needs to be worked out ...] 5.4.2 Possible transition mechanism(s) [needs to be worked out ...] 5.4.2.1 Internal communication [needs to be worked out ...] 5.4.2.2 External communication [needs to be worked out ...] 5.5 ISP case 5.5.1 Description [needs to be worked out ...] Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 13] Internet Draft Guide to IPv6 Transition Oct 1999 5.5.2 Possible transition mechanism(s) [needs to be worked out ...] 5.5.2.1 Internal communication [needs to be worked out ...] 5.5.2.2 External communication [needs to be worked out ...] 5.6 Internet Exchange [needs to be worked out ...] 5.6.1 Description [needs to be worked out ...] 5.6.2 Steps to be taken [needs to be worked out ...] 5.6.2 Possible transition mechanism(s) [needs to be worked out ...] 5.6.2.1 Internal communication [needs to be worked out ...] 5.6.2.2 External communication [needs to be worked out ...] Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 14] Internet Draft Guide to IPv6 Transition Oct 1999 6 Case studies, examples. Below are some worked out examples for situations that might occur in real live environments. Please note that the provided solutions are only meant as global directions and should not be considered as the final or even the best solution for the given situation. 6.1 Isolated IPv6 host in an IPv4 Domain 6.1.1 Introduction A Corporate Customer requires connection to a new bank system. An IPv6 host in the customer's site is needed to connect to the bank's IPv6 only site. The bank decided to implement IPv6 only, to benefit from its enhanced functionality e.g. standardised security. The bank system is a specialised system and therefore only requires communication with customer sites. The bank's border router (R2) is a dual router but nodes within the Bank's network are IPv6 only. [A diagram showing the current situation goes here] 6.1.2 Migration Requirements - IPv6 host needs to communicate with all other nodes within the customer network. - Continually maintain IPv6 functionality, therefore no use of translators should be permitted, need to maintain security and authentication procedures. - No changes should be made to the Bank's network. 6.1.3 Suitability of the Transition Categories for this Scenario IPv4 AND IPv6 MECHANISMS One of these mechanisms will be required to allow the node within the customer site to communicate with IPv6 and IPv4 nodes. TUNNELING AND ENCAPSULATION MECHANISMS Tunneling will be required to allow IPv6 packets to traverse the IPv4 network. TRANSLATORS Translators have been ruled out due to breaking end to end connectivity. 6.1.4 Suitability of these Transition Mechanisms for this Scenario DUAL STACK Dual stack will need to be deployed in the node installed in the customer's premises. To allow for some sort of routing through the IPv4 network, the border router (R1) may also need to be installed with both IPv4 and IPv6. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 15] Internet Draft Guide to IPv6 Transition Oct 1999 DUAL STACK WITH CONFIGURED TUNNELS The IPv4/IPv6 host could be configured to tunnel all IPv6 packets to the default IPv4/IPv6 router. The packets would be encapsulated with in IPv4 so that they could be routed to the router through IPv4 infrastructure. The problem is how does the host configure its IPv6 address can neighbour solicitations be transferred to the router through configured tunneling. If you are configuring a tunnel to the router R1 you might as well just tunnel all the way to the Bank's Router R2 and leave R1 as a normal IPv4 router. DUAL STACK WITH AIIH No need to use AIIH mechanism as only one host is connecting. DUAL STACK WITH DTI Not relevant as packets will mostly be traversing IPv4 networks. DUAL STACK WITH 6OVER4 6over4 could be used if the network supports multicast routing. As 6over4 only works within a domain the IPv4 router (R1) would need to support IPv6 and also to have a 6over4 interface configured. The host could then communicate to router R1 using IPv4 multicast packets. The rest of the communication path would have to be carried out by another mechanism such as configured tunneling or 6to4. 6TO4 This could be implemented at the routers R1 and R2 using their unique IPv4 addresses as an NLA ID to create a unique IPv6 address. 6.1.5 Solution 1 For this solution the IPv4 Network does Support Multicasting. Mechanisms Suggested in Solution - Dual Stack - 6over4 - 6to4 or configured tunneling. ROUTER The 6over4 mechanism will require the IPv4 network border router (R1) to be installed with IPv6 and a 6over4 interface. Note this router and the host does not need to be on the same segment, if in fact they were then there would be no requirement for 6over4. The router and the host are expected to have some IPv4 infrastructure between them. A Configured tunnel will need to be set up between R1 and R2 so the IPv6 packets can traverse the IPv4 Internet. The routers R1 and R2 could use the 6to4 method but this would mean that the router R2 would also have to implement 6to4 which in this case is not permitted Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 16] Internet Draft Guide to IPv6 Transition Oct 1999 as one of the requirements is that `No changes should be made to the Bank's network'. HOST The IPv4 host needs to firstly implement dual stack, keeping its original IPv4 address and then implementing 6over4 to allow the host to use encapsulation of IPv6 packets within IPv4 multicast packets. As this can only be used within an organisation, uses IPv4 Organisation-Local Scope (239.192.0.0) the router (R1) needs to be configured to support IPv6 routing. This host will find out its prefix by sending a router solicitation encapsulated within an IPv4 multicast packet to router R1, the router will then return with a router advertisement using the same method of encapsulation within an IPv4 multicast packet. [A diagram showing the solution goes here] 6.1.6 Solution 2 For this solution the IPv4 Network does not support Multicasting. Mechanisms Suggested in Solution - Dual Stack - Configured Tunneling HOST The host firstly needs to be implemented with the dual Stack mechanism. As the host is not going to be able to automatically be allocated a globally unique IPv6 address this will need to be input manually using the prefix of the router (R2). _Not sure if this can be done or is acceptable it could also find out its address by sending a router advertisement encapsulated within an IPv4 packet to the router R2_. Secondly the host has to be manually configured with a tunnel from host to the Bank's Router (R2). Once this is complete the Host will be able to communicate with the end node retaining the original functionality of the IPv6 packet. SECURITY IMPLEMENTATION FOR BOTH SOLUTIONS Both solutions will require some sort of Security implementation whether the use of MD5 as an authentication algorithm or DES-CBC as an encryption algorithm depends entirely on what the bank system uses. Implementers should be aware that, in addition to possible attacks against IPv6, security attacks against IPv4 must also be considered. Use of IP security at both IPv4 and IPv6 levels should nevertheless be avoided, for efficiency reasons. For example, if IPv6 is running encrypted, encryption of IPv4 would be redundant Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 17] Internet Draft Guide to IPv6 Transition Oct 1999 except if traffic analysis is felt to be a threat. If IPv6 is running authenticated, the authentication of IPv4 will add little. Conversely, IPv4 security will not protect IPv6 traffic once it leaves the IPv6-over- IPv4 domain. Therefore, implementing IPv6 security is required even if IPv4 security is available [6over4]. Although the above was written for 6over4, it is also particularly relevant to all tunneling mechanisms used. 6.2 Small/Medium Organization using a NAT 6.2.1 Introduction There are 9 offices, each office is linked using a point-to-point connection as shown in the diagram. Each site contains a DHCP, DNS and Mail server and routers are used between offices (as opposed to half bridges) to minimise traffic. Each router uses the RIP routing protocol. The network currently uses a private address space of 192.168/16 prefix with each site using a /24 prefix as shown below: [Diagram No of users and addressing in each office goes here] HEAD OFFICE The Head Offices in London has a DNS server and a NAT at the border to convert the non-globally unique IP addresses to globally unique IP addresses, this is used for security purposes as well as allowing its own internal addressing structure. All external traffic and traffic that is destined for external sources is sent through the NAT. This external traffic is minimal with a large percentage of this being SMTP traffic. Additionally the Head Office has a firewall which is configured to route all incoming SMTP traffic from the ISP's servers IP address to the internal mail router which is a Linux machine running SENDMAIL. The internal mail router then looks at the domain name in the message header and directly sends it to the relevant Mail server in each of the offices. On this same machine runs the Proxy Daemon Squid and NAT. An Intranet Server runs on a separate Linux machine using Apache. The NAT in the Billingsgate Office (Head Office) is used for external communication and is assigned one IPv4 address (194.14.1.1). All external communication will pass through this device. [Diagram showing the layout and communication links between the] [ offices goes here ] Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 18] Internet Draft Guide to IPv6 Transition Oct 1999 6.2.2 Assumptions Assume all testing and coding has been carried out on applications to allow them to run on IPv6 only hosts. If any applications cannot be run on IPv6 hosts this is detailed in Scenario 4 (IPv4 dependent applications) and therefore is not covered in this scenario. 6.2.3 Migration Requirements - To maintain a translator at the network border for ease of maintenance. - To allow for communication with IPv4 only hosts at all times during the transition. - Eventually eliminate all IPv4 traffic within the network. Suitability of the Transition Categories for this Scenario. IPV4 OR IPV6 MECHANISMS One of these mechanisms will be required to allow nodes to communicate with both IPv4 only nodes and IPv6 only nodes. TUNNELING AND ENCAPSULATION MECHANISMS The Internet is predominantly IPv4 so communication from one site to another will require the use of tunneling and encapsulation. TRANSLATORS A translator could be used to replace the NAT at the border of the network. This would work as communication outside the private network is only to one particular end-point the ISP's server, so IPv4 to IPv6 translation could occur. 6.2.4 Suitability of these Transition Mechanisms for this Scenario DUAL STACK AND NAT The dual stack mechanism if implemented in the correct order could be used on its own for communication within the private network but this would not allow communication with external nodes due to non-globally unique addressing. IPv6 addressing could be used for communication with other nodes in the network and IPv4 addressing for communication with the NAT. This mechanism will not suffer from scalability issues in this scenario, there are enough IPv4 addresses to support dual hosts as the address space is private. Manageability of two different IP addresses for each node is an issue, which will complicate administration. DUAL STACK WITH CONFIGURED TUNNELS To infer that you need configured tunnels means that you are likely to have some IPv4 infrastructure between IPv6 router or between a host and a router. In this scenario, upgrading all routers before Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 19] Internet Draft Guide to IPv6 Transition Oct 1999 hosts will be easier than configuring tunnels between hosts and routers and routers to routers. This mechanism could be used in a situation where regional offices, e.g. Birmingham and Edinburgh have upgraded to IPv6 and the Head Office still using IPv4. A tunnel would need to be configured from Birmingham to Edinburgh, encapsulating the IPv6 packet within IPv4 so that it can be routed at the Head Office. Configured tunneling is more likely to be used in large establishments or communication over a WAN where there is a large IPv4 infrastructure. DUAL STACK WITH AUTOMATIC TUNNELS If used would allow hosts to be updated before routers. Each host would need to be configured to use IPv4-Compatible IPv6 addresses, tunneling would then occur between end-points. This network is only small with only a few routers, all routers and routing are internal to the organisation and as such would be easier to upgrade than have the added problems of routing "flat" addresses and performance degradation of encapsulating most IPv6 packets within IPv4 packet. DUAL STACK WITH AIIH One of the main reasons in using the AIIH mechanism is if there are not enough IPv4 addresses for each Dual Stack node on the network. In this scenario they are using a private address space and therefore are not limited (within reason) to a number of IPv4 addresses. DUAL STACK WITH DTI Requires that all routers would need to support IPv6. If this is the case then if you have the Dual stack and IPv6 routing through the private network why use DTI? This mechanism would be used as part of a complex solution for larger organisations with direct external connections to the Internet and especially in the later stages of transitioning. I don't think its benefits could be of use in this scenario. DUAL STACK AND TRANSLATOR A NAT is already used at the border of the network which suits their needs. All nodes in the organisation can be upgraded to dual stack and the NAT be upgraded to convert IPv6 to IPv4 addresses. This would allow all nodes in the network to be able to communicate using only IPv6 and the translator used for converting IPv6 headers to IPv4. TRANSLATOR Could be used on its own to replace the NAT already installed meaning that the internal structure of the network could remain the same without any alterations within the private network. Could be used in the later stages once migration has been completed and most sites are using IPv6. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 20] Internet Draft Guide to IPv6 Transition Oct 1999 6OVER4 The internal network does not use multicasting so this mechanism is not relevant for this scenario. DUAL STACK, 6TO4 AND TRANSLATOR Could be used to give the Translator a unique IPv6 address by using the unique IPv4 address for the translator and using it as an NLA. This would allow each node internal to the organisation to have a unique IPv6 address. 6.2.5 Solution 1 Reasoning behind the solution Currently uses private address space so there is no problem with limited IPv4 addresses. The easiest approach in transitioning would be to use dual stack on all hosts. This solution does not require the complex methods of encapsulation. Mechanisms Suggested in Solution - Dual Stack - Translator - 6to4 (Option) 6.2.5.1 Stage 1: Head Office Starting with the Head Office in London as most traffic will be routed through here, it is essential that this is the first to be upgraded to IPv6 to allow for communication to allow routing from regional sites. The order of Implementation within the Head Office can be followed from that in Scenario 2, Solution 1 but has been detailed again below: DEFAULT ROUTER (R1) Connects with all other offices. A software upgrade will be required to allow this to operate as a dual router. The router will treat IPv6 as an independent protocol so therefore RIPv2 will need to be activated and configured for IPv6. DHCP SERVER Depending on whether this server is necessary is dependent on whether stateful auto-configuration is required. If required will need to be upgraded to dual stack to allow allocation of IPv4 addresses out of the private address space and also stateful IPv6 addresses. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 21] Internet Draft Guide to IPv6 Transition Oct 1999 DNS SERVER Upgraded to a dual stack, a requirement for hosts to look up a destination node using DNS to find out if v4 or v6 address is to be used. PROXY SERVER/TRANSLATOR Will need to be bilingual. This is the conversion point for the network and will be translating between IPv6 and IPv4 and vice versa. The firewall will need no new configuration as the data sent to and from will be IPv4 format, until ISP migrates to IPv6. SERVERS Once the above have been converted then the Mail Server and any File Servers will need IPv6 installed. Again the Mail server may require some extra configuration. WORKSTATION Now all the dependencies have been configured all workstations will need to be upgraded to support IPv6. This can be in any order and there is no time limit. 6.2.5.2 Stage 2: London Offices Once the head office has been upgraded, the regional offices in London can be upgraded. These can be carried out in whichever order desired. The following implementation rule shown in stage 1 must apply to each site: - Default Router - DHCP Server - DNS Server - Other Servers e.g. Mail Server etc. - Workstations 6.2.5.3 Stage 3: Regional Offices Once the London sites have been upgraded the regional sites can be upgraded. The order is as follows: Birmingham Manchester Glasgow Edinburgh The order doesn't have to be followed but it should be noted that if Glasgow is upgraded before Manchester and Birmingham then tunnels will have to be configured from Glasgow's Router to the Head Office Router. Implementation in each office should be followed in accordance with Stage 1 and Stage 2. 6.2.5.4 Stage 4: Final Stage Once all nodes within the organisation have been upgraded to IPv6, Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 22] Internet Draft Guide to IPv6 Transition Oct 1999 the IPv4 component in each node can be deactivated to allow for just IPv6 traffic on the network. Deactivation will obviously have to be done in reverse order to the implementation i.e. disable IPv4 on the workstations first and routers last. The translator at the border will convert all IPv6 headers into IPv4 headers and vice versa. Normally it is difficult for translators to convert from IPv4 to IPv6 e.g. when external to internal communication is initiated. Only one source in this case will be externally initiating communication and this will be the ISP server when sending SMTP traffic. The translator (will have to be an application translator) at the border of the network can detect and forward SMTP traffic to the correct node internally. 6TO4 OPTION The 6to4 mechanism could be used in conjunction with the translator. The one unique IP address associated with the translator could be assigned to the NLA field creating a globally unique IPv6 prefix. This would allow all nodes within the organisation to have a globally unique IPv6 address and allow the NAT to receive either IPv6 or IPv4 packets. 6.2.6 Solution 2 Mechanisms Suggested in Solution - Translator If there was absolutely no need for the implementation of IPv6 within the organisation or if all IPv4 applications required intensive configuration to convert for IPv6 support there is another solution. In this case the NAT could just be upgraded to a translator supporting external IPv6 traffic and leaving the current internal infrastructure the same. This adds to the problem of how IPv4 nodes can work out how to send to an IPv6 address external to the organisation. As all external traffic would be sent to the ISP address, the translator could be configured to send all external traffic to this one IPv6 address. The nodes could be configured manually to send any external data to a certain IPv4 address, which could be configured by routers to send on to the translator. The translator would need to know that this IPv4 address should be converted to the IPv6 address of the ISP server. This would be quite complex and it would be far easier, for long term administration and maintenance, to migrate the network to IPv6. 6.3 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 Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 23] Internet Draft Guide to IPv6 Transition Oct 1999 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. 6.3.1 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]. 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. 6.3.3 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 Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 24] Internet Draft Guide to IPv6 Transition Oct 1999 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). 6.4 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 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: 6.4.1 Model 1 - IE operator requests an NLA Obtain globally unique address space. This can be an NLA from a Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 25] Internet Draft Guide to IPv6 Transition Oct 1999 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. 6.4.3 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. - 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. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 26] Internet Draft Guide to IPv6 Transition Oct 1999 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. References [6BONE] http://www.6bone.net/ [6TO4] B. Carpenter, K Moore, "Connection of IPv6 Domains via IPv4 Clouds without Explicit Tunnels", draft-ietf-ngtrans-6to4-03.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). [BITSv6] K. Tsuchiya, H. Higuchi, Y. Atarashi, "Dual Stack Hosts using the Bump-in-the-Stack technique", draft-ietf-ngtrans-dual-stack-hosts-02.txt (work in progress). [BROKER] A. Durand, P. Fasano, I. Guardini, D. Lento, "IPv6 Tunnel Broker", draft-ietf-ngtrans-broker-00.txt (work in progress). [CSELT] https://carmen.cselt.it/ipv6tb [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] M. Crawford, C. Huitema, S. Thomson, "DNS Extensions to Support IP Version 6", draft-ietf-ipngwg-dns-lookups-05.txt (work in progress). [DSTM] J. Bound, L. Toutain, H. Affifi, "Dual Stack Transition Mechanism (DSTM)", draft-ietf-ngtrans-dstm-00.txt (work in progress). Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 27] Internet Draft Guide to IPv6 Transition Oct 1999 [FREENET6] http://www.freenet6.net/ [IRALLOC] Regional IRs, "Provisional IPv6 assignment and allocation policy document (Draft 6; 27 May 1999)", ipv6policy-draft-090699.txt (work in progress). [NAT-PT] George Tsirtsis, Pyda Srishuresh, "Network Address Translation - Protocol Translation (NAT-PT)", draft-ietf-ngtrans-natpt-06.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. [RFC1928] M. Leech, M. Ganis, Y. Lee, R. Kuris, D. Koblas and L. Jones, "SOCKS Protocol Version 5", RFC 1928, March 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. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 28] Internet Draft Guide to IPv6 Transition Oct 1999 [RFC2374] R. Hinden, M. O'Dell, S. Deering, "An IPv6 Aggregatable Global Unicast Address Format", RFC 2374, July 1998. [RFC2529] B. Carpenter, C. Jung, "Transmission of IPv6 over IPv4 Domains without Explicit Tunnels", RFC2529, March 1999. [RFC2545] P. Marques, F. Dupont, "Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing", RFC2545, March 1999. [RFC2546] A. Durand, B. Buclin, "6Bone Routing Practice", RFC 2546, March 1999. [RFC2673] Matt Crawford, "Binary Labels in the Domain Name System", RFC 2673, August 1999. [SIIT] Erik Nordmark, "Stateless IP/ICMP Translator", draft-ietf-ngtrans-siit-06.txt (work in progress). [SOCKS-EXT] H. Kitamura, "SOCKSv5 Protocol Extensions for IPv6/IPv4 Communication Environment", draft-kitamura-socks-ipv6-01.txt (work in progress). [SOCKS-GATE] H. Kitamura, A. Jinzaki, S. Kobayashi, "A SOCKS-based IPv6/IPv4 Gateway Mechanism", draft-ietf-ngtrans-socks-gateway-02.txt (work in progress). [TELEBIT] http://www.tbit.dk/ [ZEBRA] http://www.zebra.org/ Authors' Addresses Wim Biemolt Marijke Kaat SURFnet ExpertiseCentrum bv SURFnet ExpertiseCentrum bv P.O. Box 19115 P.O. Box 19115 3501 DC Utrecht 3501 DC Utrecht The Netherlands The Netherlands Phone: +31 30 230 5305 Phone: +31 30 230 5305 Fax: +31 30 230 5329 Fax: +31 30 230 5329 Email: Wim.Biemolt@sec.nl Email: Marijke.Kaat@sec.nl Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 29] Internet Draft Guide to IPv6 Transition Oct 1999 Ronald van der Pol Henk Steenman SURFnet bv AT&T, ICoE P.O. Box 19035 Laarderhoogtweg 25 3501 DA Utrecht 1101 EB Amsterdam The Netherlands The Netherlands Phone: +31 30 230 5305 Phone: +31 20 409 7656 Fax: +31 30 230 5329 Fax: +31 20 453 1574 Email: Ronald.vanderPol@surfnet.nl Email: Henk.Steenman@icoe.att.com Tim Larder Barbrook Cottage Holmesdale Road South Nutfield Surrey RH1 4JE Email: tim.larder@virgin.net Appendix A. Ipv6 Address Issues A.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. Most sites will get a /48 prefix with 16 bits for subnetting and 64 bits for interface ID addressing. This means that 65536 subnets can be defined and in each subnet almost 20 trillion hosts can be numbered. 0 48 64 127 +---------------------------------+--------+--------------------+ | prefix | subnet | Interface ID | +---------------------------------+--------+--------------------+ At present, there is an experimental network called the "6bone" which is operated based on IPv6. For this network, a part of the Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 30] Internet Draft Guide to IPv6 Transition Oct 1999 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. A.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 minimize 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 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. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 31] Internet Draft Guide to IPv6 Transition Oct 1999 +--+----------+---------+---------+--------+--------------------+ | 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) An example of IPv6 address usage can be found in appendix A. A.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. In the ipv6-site objects the IPV6 applications that are supported on that specific site can be found. The database can be queried by using a modified whois client or 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. A.3 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. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 32] Internet Draft Guide to IPv6 Transition Oct 1999 3FFE:1234:5678::/48 | | I1 +-----+-----+ I2 +-------+ R1 +-------------------+ | +---------+-+ | | | I3 | +-------+-------+ +----+ +-----+----+ | | | | 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: I1 3FFE:1234:5678:2000::/50 I2 3FFE:1234:5678:0000::/49 I3 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 I2 3FFE:1234:5678:1000::/49 free 3FFE:1234:5678:2000::/49 I1 + I3 3FFE:1234:5678:3000::/49 free ..... ... 3FFE:1234:5678:F000::/49 free 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 Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 33] Internet Draft Guide to IPv6 Transition Oct 1999 ..... ... 3FFE:1234:5678:02FF::/64 reserved for R2 3FFE:1234:5678:0300::/64 free ..... ... 3FFE:1234:5678:2000::/49 ------------------------ 3FFE:1234:5678:2000::/50 I1 3FFE:1234:5678:2100::/50 reserved for I1 3FFE:1234:5678:2200::/50 reserved for I1 3FFE:1234:5678:2300::/50 I3 3FFE:1234:5678:2400::/50 reserved for I3 3FFE:1234:5678:2500::/50 reserved for I3 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 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 Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 34] Internet Draft Guide to IPv6 Transition Oct 1999 Appendix B. IPv6 and DNS B.1 Forward mapping A host's 128 bit IPv6 address can be stored with an AAAA 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 record in IPv4, for example: $ORIGIN ipv6.surfnet.nl. ... zesbot IN A 192.87.110.60 Note that both A and AAAA records for a given zone 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 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 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 records are widely deployed it is expected that the AAAA records are no longer needed. B.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 example the IPv4 address Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 35] Internet Draft Guide to IPv6 Transition Oct 1999 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. 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. Note that the IPv4 and IPv6 reverse mappings are stored in different DNS data files. B.3 Implementations Most DNS implementations will be able to deal with the reverse mapping as used with IPv6 addresses. However the AAAA 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 record [DNSLOOKUP] or binary labels [RFC2673]. 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. Biemolt, Kaat, Larder, vd Pol, Steenman Expires April 2000 [page 36]