This is an unedited version - Megan 04/20/92 BGP/CIDR BOF Wednesday, 18 March, 1992, 1:30-3:30pm. San Diego IETF Chaired by Yakov Rekhter (IBM Watson) and Peer Ford (LANL) The BGP working group met jointly with people interested in Classless InterDomain Routing (CIDR) in a BOF to discuss the development of an addressing plan which can be used for IP. CIDR would allow collapsing adjacent network addresses into a single prefix, and that prefix would be passed within the routing system as the route to all the "collapsed" networks. CIDR is proposed to mitigate the scaling problems in the Internet's routing system which are due to ``flat routing'' and the fact that the Internet will shortly (1-3 years) run out of class B addresses. When the Internet runs out of class B addresses, the current available option is to allocate class C network addresses which will require networks which have more than 255 end systems to advertise multiple network addresses to the global Internet routing system. The purpose of the BOF was to discuss various schemes for assigning and collapsing addresses, including collapsing along a multi-level hierarchy, what the hierarchies would look like (size and placement), what the mapping between network providers and collapsed prefixes would look like. There was a significant turnout of interested people and the discussion was quite spirited. Yakov Rekhter led off the discussion with a brief overview of CIDR and an explanation of the goals of the BOF. He then presented a proposal for Address Assignment Authorities (AAAs). Following are notes from his slides: {beginning of slides} Goal: "Recommended Guidelines for IP Address Assignment." To achieve: consistency efficiency ease of management and coordination "Address Assignment Authority" (AAA) Distributed way of managing address space Promote routing information efficiency Recursive ==> delegation of AAA Need to extend CIDR Pure class "C" supernetting provides _limited_ extension with respect to the IP address space Large portions of A & B are still unused! "AAA" concept needs to be applied to the _whole_ IP address space. How to carve address space? Top-Down to ensure feasible routing (wrt scaling) How many levels Branching Factor at each level (deep trees vrs bushy trees) Need to determine number of top level AAAs. CIDR & "NSAP Address Guidelines" Attempt to solve the same problem May benefit from coordination between NSAP address assignment and IP address assignment Single AAA --> IP & NSAP IP and NSAP topology is likely to be congruent Address administration boundaries are likely to be congruent: a service provider provides both IP and CLNP services the same geographical area provides both IP and CLNP services {end of Slides} Yakov went on to propose a possible allocation of AAA's, which was to assume a top down allocation of 1000 AAAs which would require coding top level AAA coding of 10 bits. Within the class c address space this would imply that each AAA would have a maximum of 1000 class C network addrs. This was a good starting point for discussing network topology issues, and "who would be candidates for being AAAs?". There were several people disagreeing with Yakov's proposal for picking a fixed size breakout for top level AAAs. Several people proposed an allocation of top level AAAs which was scaled by the size of the community one was trying to serve, perhaps using the population size or the size of the telephone networks as scaling factors. It was noted that using a Kampei style address assignment scheme might be a good thing to do here. There was concern expressed for deploying CIDR too soon, before a sufficient technology base was deployed for aggregating multiple class C network addresses. Several people noted that this may have severe impacts on intra-domain routing protocols since an aggregated prefix would have to be exploded to its constituent class C networks if the routing protocols did not handle aggregation correctly (RIP and EGP). There was significant discussion of how to carve up class A and class B network addresses effectively. There was general concurrence that for the time being class A's should not be allocated. This would be until there is a technology base which can be used with carved up A's. It was noted that this would be feasible once most routers "knew how to do variable length subnets". There was discussion on how Class C# (Solensky and Kastenholz) could coexist with CIDR. Jon Postel gave a short description of what the IANA does and how it decides who gets what network addresses. The discussion clearly overran the time allotment and future discussion of this issue was proposed to continue on Email using the big-internet@munnari.oz.au mailing list. Yakov Rekhter agreed to discuss with the IESG about forming a working group to work on an IP addressing plan.