--- 1/draft-ietf-ipngwg-unicast-aggr-01.txt 2006-12-03 11:57:35.000000000 +0100 +++ 2/draft-ietf-ipngwg-unicast-aggr-02.txt 2006-12-03 11:57:35.000000000 +0100 @@ -1,38 +1,38 @@ INTERNET-DRAFT R. Hinden, Ipsilon Networks -June 12, 1997 M. O'Dell, UUNET +July 16, 1997 M. O'Dell, UUNET S. Deering, Cisco An IPv6 Aggregatable Global Unicast Address Format - + Status of this Memo This document is an Internet Draft. 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. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as a ``working draft'' or ``work in progress.'' Please check the 1id-abstracts.txt listing contained in the internet- drafts Shadow Directories on nic.ddn.mil, nnsc.nsf.net, nic.nordu.net, ftp.nisc.sri.com, or munnari.oz.au to learn the current status of any Internet Draft. - This internet draft expires on December 13, 1997. + This internet draft expires on January 17, 1998. 1.0 Introduction This document defines an IPv6 aggregatable global unicast address format for use in the Internet. The address format defined in this document is consistent with the IPv6 Protocol [IPV6] and the "IPv6 Addressing Architecture" [ARCH]. It is designed to facilitate scalable Internet routing. This documented replaces RFC 2073, "An IPv6 Provider-Based Unicast @@ -49,21 +49,21 @@ and Multicast. This document defines a specific type of Unicast address. In this document, fields in addresses are given specific names, for example "subnet". When this name is used with the term "ID" (for "identifier") after the name (e.g., "subnet ID"), it refers to the contents of the named field. When it is used with the term "prefix" (e.g. "subnet prefix") it refers to all of the addressing bits to the left of and including this field. - IPv6 unicast addresses are designed assuming that the internet + IPv6 unicast addresses are designed assuming that the Internet routing system makes forwarding decisions based on a "longest prefix match" algorithm on arbitrary bit boundaries and does not have any knowledge of the internal structure of IPv6 addresses. The structure in IPv6 addresses is for assignment and allocation. The only exception to this is the distinction made between unicast and multicast addresses. The specific type of an IPv6 address is indicated by the leading bits in the address. The variable-length field comprising these leading bits is called the Format Prefix (FP). @@ -75,24 +75,30 @@ Format Prefix is defined here. 3.0 IPv6 Aggregatable Global Unicast Address Format This document defines an address format for the IPv6 aggregatable global unicast address assignment. The authors believe that this address format will be widely used for IPv6 nodes connected to the Internet. This address format is designed to support both the current provider-based aggregation and a new type of exchange-based aggregation. The combination will allow efficient routing - aggregation for both sites that connect directly to providers and + aggregation for sites that connect directly to providers and for sites that connect to exchanges. Sites will have the choice to connect to either type of aggregation entity. + While this address format is designed to support exchange-based + aggregation (in addition to current provider-based aggregation) it is + not dependent on exchanges for it's overall route aggregation + properties. It will provide efficient route aggregation with only + provider-based aggregation. + Aggregatable addresses are organized into a three level hierarchy: - Public Topology - Site Topology - Interface Identifier Public topology is the collection of providers and exchanges who provide public Internet transit services. Site topology is local to a specific site or organization which does not provide public transit service to nodes outside of the site. Interface identifiers identify @@ -105,289 +111,252 @@ | +--| X1 | +| X2 | | ______________ / | |-+ ______________ / | |-- +/ \+ +-+--+ \ / \+ +----+ ( P2 ) / \ +( P4 ) --+\______________/ / \ \______________/ | / \ | | | / | | | | / | | | _|_ _/_ _|_ _|_ _|_ / \ / \ / \ / \ / \ - ( S.A ) ( S.B ) ( P5 ) ( P6 )( S.D ) + ( S.A ) ( S.B ) ( P5 ) ( P6 )( S.C ) \___/ \___/ \___/ \___/ \___/ | / \ _|_ _/_ \ ___ / \ / \ +-/ \ - ( S.E ) ( S.F ) ( S.G ) + ( S.D ) ( S.E ) ( S.F ) \___/ \___/ \___/ As shown in the figure above, the aggregatable address format is designed to support long-haul providers (shown as P1, P2, P3, and P4), exchanges [EXCH] (shown as X1 and X2), multiple levels of providers (shown at P5 and P6), and subscribers (shown as S.x) Exchanges (unlike current NAPs, FIXes, etc.) will allocate IPv6 addresses. Organizations who connect to these exchanges will also - subscribe (directly, indirectly via the exchange, etc.) for long- - haul service from one or more long-haul providers. Doing so, they - will achieve addressing independence from long-haul transit - providers. They will be able to change long-haul providers without - having to renumber their organization. They can also be multihomed - via the exchange to more than one long-haul provider without having - to have address prefixes from each long-haul provider. Note that the + subscribe (directly, indirectly via the exchange, etc.) for long-haul + service from one or more long-haul providers. Doing so, they will + achieve addressing independence from long-haul transit providers. + They will be able to change long-haul providers without having to + renumber their organization. They can also be multihomed via the + exchange to more than one long-haul provider without having to have + address prefixes from each long-haul provider. Note that the mechanisms used for this type of provider selection and portability are not discussed in the document. 3.1 Aggregatable Global Unicast Address Structure The aggregatable global unicast address format is as follows: | 3 | 13 | 32 | 16 | 64 bits | +---+-----+-----------+--------+--------------------------------+ - |FP | TLA | NLA* | SLA* | Interface ID | + |FP | TLA | NLA ID | SLA ID | Interface ID | + | | ID | | | | +---+-----+-----------+--------+--------------------------------+ <--Public Topology---> Site <--------> Topology <------Interface Identifier-----> Where FP Format Prefix (001) - TLA Top-Level Aggregator - NLA* Next-Level Aggregator(s) - SLA* Site-Level Aggregator(s) + TLA ID Top-Level Aggregation Identifier + NLA ID Next-Level Aggregation Identifier + SLA ID Site-Level Aggregation Identifier INTERFACE ID Interface Identifier The following sections specify each part of the IPv6 Aggregatable Global Unicast address format. -3.2 Top-Level Aggregator - - Top-Level Aggregators (TLA) are the top level in the routing - hierarchy. Default-free routers must have a routing table entry for - every active TLA. They may have additional entries, but the routing - topology at all levels must be designed to minimize the number of - additional entries fed into the default free routing tables. - - This addressing format supports 8,192 (2^^13) TLA's. Additional TLA - may be added by using this format for additional format prefixes. - The addition of another FP will add another 8,192 TLA's. - -3.2.1 Assignment of TLAs - - TLAs are assigned to organizations providing public transit topology. - They are specifically not assigned to organizations only providing - leaf or private transit topology. TLA assignment does not imply - ownership. It does imply stewardship over valuable Internet - property. - - The IAB and IESG have authorized the Internet Assigned Numbers - Authority (IANA) as the appropriate entity to have the responsibility - for the management of the IPv6 address space as defined in [ALLOC]. - - The IANA will assign small blocks of TLAs to IPv6 registries. The - registries will assign the TLAs to organizations meeting the - requirements for TLAs. When the registries have assigned all of - their TLAs they can request that the IANA give them another block. - The blocks do not have to be contiguous. The IANA may also assign - TLAs to organizations directly. - - Organizations assigned TLAs are required to meet the following - requirements: - - - Must have a plan to offer public native IPv6 service within 6 - months from assignment. Plan must include plan for NLA - allocation. - - - Plan or track record providing public internet transit service on - fair, reasonable, and non-discriminatory terms, to other - providers. TLAs must not be assigned to organizations that are - only providing leaf service even if multihomed. - - - Must provide registry services on fair, reasonable, and non- - discriminatory terms, for the NLA address space it is responsible - for under its TLA. This must include both sites and next level - providers. +3.2 Top-Level Aggregation ID - - Must provide transit routing and forwarding to all assigned TLAs - on fair, reasonable, and non-discriminatory terms. Organizations - are not allowed to filter out any specific TLA's (except - temporarily for diagnostic purposes or emergency repair purposed). + Top-Level Aggregation Identifiers (TLA ID) are the top level in the + routing hierarchy. Default-free routers must have a routing table + entry for every active TLA ID and will probably have additional + entries providing routing information for the TLA ID in which they + are located. They may have additional entries in order to optimize + routing for their specific topology, but the routing topology at all + levels must be designed to minimize the number of additional entries + fed into the default free routing tables. - - Periodically (interval set by registry) provide to registry - utilization statistics of the TLA it has custody of. The - organization must also show evidence of carrying TLA routing and - transit traffic. This can be in the form of traffic statistics, - traceroutes, routing table dumps, or similar means. + This addressing format supports 8,192 (2^13) TLA ID's. Additional + TLA ID's may be added by using this format for additional format + prefixes. The addition of another FP will add another 8,192 TLA + ID's. - Organizations which are given custody of a TLA and fail to continue - to meet these may have the TLA custody revoked. + The rules for TLA ID assignment are defined in [TLAASN]. -3.3 Next-Level Aggregator(s) +3.3 Next-Level Aggregation Identifier - Next-Level Aggregator(s) are used by TLA's to create an addressing - hierarchy and to identify sites. The TLA can assign the top part of - the NLA in a manner to create an addressing hierarchy appropriate to - its network. It can use the remainder of the bits in the field to - identify sites it wishes to serve. This is shown as follows: + Next-Level Aggregation Identifier's are used by organizations + assigned a TLA ID to create an addressing hierarchy and to identify + sites. The organization can assign the top part of the NLA ID in a + manner to create an addressing hierarchy appropriate to its network. + It can use the remainder of the bits in the field to identify sites + it wishes to serve. This is shown as follows: | n | 32-n bits | 16 | 64 bits | +-----+--------------------+--------+-----------------+ - |NLA1 | Site | SLA* | Interface ID | + |NLA1 | Site ID | SLA ID | Interface ID | +-----+--------------------+--------+-----------------+ - Each TLA receives 32 bits of NLA* space. This NLA* space allows each - TLA to provide service to about as many organizations as the current - IPv4 internet can support total nodes. + Each organization assigned a TLA ID receives 32 bits of NLA ID space. + This NLA ID space allows each organization to provide service to + approximately as many organizations as the current IPv4 Internet can + support total nodes. - The TLAs may also support NLAs in their own Site ID space. This - allows the TLAs to provide service to organizations providing public - transit service and organizations who do not. The organizations - providing public transit service become NLA's themselves. These NLAs - may also choose to use their Site ID space to support other NLAs. - This is shown as follows: + Organizations assigned TLA ID's may also support NLA ID's in their + own Site ID space. This allows the organization assigned a TLA ID to + provide service to organizations providing public transit service and + to organizations who do not provide public transit service. These + organizations receiving an NLA ID may also choose to use their Site + ID space to support other NLA ID's. This is shown as follows: | n | 32-n bits | 16 | 64 bits | +-----+--------------------+--------+-----------------+ - |NLA1 | Site | SLA* | Interface ID | + |NLA1 | Site ID | SLA ID | Interface ID | +-----+--------------------+--------+-----------------+ | m | 32-n-m | 16 | 64 bits | +-----+--------------+--------+-----------------+ - |NLA2 | Site | SLA* | Interface ID | + |NLA2 | Site ID | SLA ID | Interface ID | +-----+--------------+--------+-----------------+ | o |32-n-m-o| 16 | 64 bits | +-----+--------+--------+-----------------+ - |NLA3 | Site | SLA* | Interface ID | + |NLA3 | Site ID| SLA ID | Interface ID | +-----+--------+--------+-----------------+ - The NLA delegation works in the same manner as CIDR delegation in - IPv4 [CIDR]. TLAs are required to assume registry duties for the - NLAs. Each level of NLA is required to assume registry duties for - the next level NLA. + The rules for NLA ID assignment are defined in [TLAASN]. - The design of the bit layout of the NLA space for a specific TLA is - left to the organization responsible for that TLA. Likewise the - design of the bit layout of the next level NLA is the responsibility - of the previous level NLA. It is recommended that organizations - assigning NLA address space use "slow start" allocation procedures as - is currently done with IPV4 CIDR blocks. + The design of the bit layout of the NLA ID space for a specific TLA + ID is left to the organization responsible for that TLA ID. Likewise + the design of the bit layout of the next level NLA ID is the + responsibility of the previous level NLA ID. It is recommended that + organizations assigning NLA address space use "slow start" allocation + procedures as is currently done with IPv4 CIDR blocks. - The design of an NLA allocation plan is a tradeoff between routing + The design of an NLA ID allocation plan is a tradeoff between routing aggregation efficiency and flexibility. Creating hierarchies allows for greater amount of aggregation and results in smaller routing - tables. Flat NLA assignment provides for easier allocation and - attachment flexibility but results in larger routing tables. + tables. Flat NLA ID assignment provides for easier allocation and + attachment flexibility, but results in larger routing tables. -3.4 Site-Level Aggregator(s) +3.4 Site-Level Aggregation Identifier - The SLA* field is used by an individual organization to create its + The SLA ID field is used by an individual organization to create its own local addressing hierarchy and to identify subnets. This is analogous to subnets in IPv4 except that each organization has a much - greater number of subnets. The 16 bit SLA* field support 65,535 + greater number of subnets. The 16 bit SLA ID field support 65,535 individual subnets. - Organizations may choose to either route their SLA* "flat" (e.g., not - create any logical relationship between the SLA identifiers which + Organizations may choose to either route their SLA ID "flat" (e.g., + not create any logical relationship between the SLA identifiers that results in larger routing tables), or to create a two or more level - hierarchy (which results in smaller routing tables) in the SLA* + hierarchy (that results in smaller routing tables) in the SLA ID field. The latter is shown as follows: | n | 16-n | 64 bits | +-----+------------+-------------------------------------+ |SLA1 | Subnet | Interface ID | +-----+------------+-------------------------------------+ | m |16-n-m | 64 bits | +----+-------+-------------------------------------+ |SLA2|Subnet | Interface ID | +----+-------+-------------------------------------+ - The approach chosen for how to the structure of an SLA* field is the + The approach chosen for structuring an SLA ID field is the responsibility of the individual organization. - The number of subnets supported should be sufficient for all but the - largest of organizations. Organizations which need additional - subnets can arrange with the organization they are obtaining internet - service from to obtain additional site identifiers and use this to - create additional subnets. + The number of subnets supported in this address format should be + sufficient for all but the largest of organizations. Organizations + which need additional subnets can arrange with the organization they + are obtaining Internet service from to obtain additional site + identifiers and use this to create additional subnets. 3.5 Interface ID Interface identifiers are used to identify interfaces on a link. They are required to be unique on that link. They may also be unique over a broader scope. In many cases an interface's identifier will - be the same as that interface's link-layer address. Interface IDs - used in the aggregatable global unicast address format are required - to be 64 bits long and to be constructed in IEEE EUI-64 format - [EUI-64]. These identifiers may have global scope when a global - token (e.g., IEEE 48bit MAC) is available or may have local scope - where a global token is not available (e.g., serial links, tunnel - end-points, etc.). The "u" bit (universal/local bit in IEEE EUI-64 - terminology) in the EUI-64 identifier must be set correctly, as - defined in [ARCH], to indicate global or local scope. + be the same or be based on the interface's link-layer address. + Interface IDs used in the aggregatable global unicast address format + are required to be 64 bits long and to be constructed in IEEE EUI-64 + format [EUI-64]. These identifiers may have global scope when a + global token (e.g., IEEE 48bit MAC) is available or may have local + scope where a global token is not available (e.g., serial links, + tunnel end-points, etc.). The "u" bit (universal/local bit in IEEE + EUI-64 terminology) in the EUI-64 identifier must be set correctly, + as defined in [ARCH], to indicate global or local scope. The procedures for creating EUI-64 based Interface Identifiers is defined in [ARCH]. The details on forming interface identifiers is defined in the appropriate "IPv6 over " specification such as "IPv6 over Ethernet" [ETHER], "IPv6 over FDDI" [FDDI], etc. 4.0 Acknowledgments The authors would like to express our thanks to Thomas Narten, Bob Fink, Matt Crawford, Allison Mankin, Jim Bound, Christian Huitema, - Scott Bradner, Brian Carpenter, and John Stewart. for their review - and constructive comments. + Scott Bradner, Brian Carpenter, and John Stewart for their review and + constructive comments. 5.0 References [ALLOC] IAB and IESG, "IPv6 Address Allocation Management", RFC1881, December 1995. [ARCH] Hinden, R., "IP Version 6 Addressing Architecture", - Internet Draft, , May - 1997. + Internet Draft, , + July 1997. + + [AUTH] Atkinson, R., "IP Authentication Header", RFC1826, August + 1995. [AUTO] Thompson, S., Narten T., "IPv6 Stateless Address Autoconfiguration", RFC1971, August 1996. [CIDR] Fuller, V., T. Li, K. Varadhan, J. Yu, "Supernetting: an Address Assignment and Aggregation Strategy", RFC1338. [ETHER] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", Internet Draft, , March 1997. [EUI64] IEEE, "Guidelines for 64-bit Global Identifier (EUI-64) Registration Authority", http://standards.ieee.org/db/oui/tutorials/EUI64.html, March 1997. - [EXCH] Hinden, R., Huitema, C. "Internet Exchanges", document + [EXCH] Huitema, C., R. Hinden, "Internet Exchanges", document under preparation. [FDDI] Crawford, M., "Transmission of IPv6 Packets over FDDI Networks", Internet Draft, , March 1997. [IPV6] Deering, S., Hinden, R., Editors, "Internet Protocol, Version 6 (IPv6) Specification", RFC1883, December 1995. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC2119, BCP14, March 1997. + [TLAASN] Hinden, R., "TLA and NLA Assignment Rules", Internet Draft, + , July 1997. + 6.0 Security Considerations - Documents of this type do not directly impact the security of the - Internet infrastructure or its applications. + IPv6 addressing documents do not have any direct impact on Internet + infrastructure security. Authentication of IPv6 packets is defined + in [AUTH]. 7.0 Authors' Addresses Robert M. Hinden phone: 1 408 990-2004 Ipsilon Networks, Inc. email: hinden@ipsilon.com 232 Java Drive Sunnyvale, CA 94089 USA Mike O'Dell phone: 1 703 206-5890