Re: [RRG] Convergence - design-goals-01: IPv4 utilization, portability
Robin Whittle <rw@firstpr.com.au> Thu, 06 December 2007 01:49 UTC
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Date: Thu, 06 Dec 2007 12:49:31 +1100
From: Robin Whittle <rw@firstpr.com.au>
Organization: First Principles
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To: Routing Research Group list <rrg@psg.com>
Cc: David Meyer <dmm@1-4-5.net>
Subject: Re: [RRG] Convergence - design-goals-01: IPv4 utilization, portability
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Short version: I think the Design Goals could be improved in terms of terminology eg. "control plane" and to include the following goals: Portability Since many end-users want this and since ITR-ETR schemes do provide it, it should be one of the goals. IPv4 utilization I see this as being inextricably entwined with successful resolution of the IPv4 routing scalability problem. Therefore, it should be a core goal, rather than simply a goal which is inferred, depending on how the solution to the scaling problem is understood. Mobility Since efficient, low path stretch mobility would be a huge benefit to many end-users in the future (a bit like trying to imagine cell-phone demand in 1975), and since at least one ITR-ETR scheme (Ivip) is intended to provide this, mobility support should be an "additional", or "good if we can get it too" goal. David Meyer wrote: > At the RRG meeting on Monday we talked a bit about > this ("convergence"). IIRC, Tony mentioned the > design-goals document (draft-irtf-rrg-design-goals-01.txt) > as a source of evaluation criteria. My concern is that > there is not enough detail in the draft to form the basis > of a decision process (which ever one we use, which is > another question). > > So my question is: Do folks feel that this document > contains sufficient detail (at least to a first > approximation) to make an informed decision, and if not, > how do we plan to do to obtain that detail? I think it would be good to discuss the current draft and devise a more comprehensive version of it. On 14 July I wrote a critique: http://psg.com/lists/rrg/2007/msg00199.html but there was no follow-up messages, and I don't recall any other critiques. I think there are improvements to be made in terminology. I also think that since ITR-ETR / map&encap schemes provide portability of addresses (apologies to Brian and others who wince at this phrase) that this should be a goal as well. Portability with sufficient speed of updates - as Ivip is intended to achieve - would enable a new and previously unanticipated support mechanism for mobility. So if there are two proposals with roughly the same benefits in other terms, but one is clearly better for supporting mobility, I think the Design Goals document should provide a basis for choosing the one with the mobility benefits. Another criteria or goal I think the Design Goals should contain is the better utilisation of IPv4 address space. My July critique doesn't mention this. There is a range of opinions on how much more can be achieved - and I guess some people don't care much, since they see IPv4 as a dead end anyway. Geoff Huston estimates utilization of 5 to 20% of currently advertised space. Even 20% leaves room for a factor of 2 or 3 improvement, at a time when we are supposedly running out of IPv4 space. Essentially every Internet user relies on IPv4 - and will continue to do so for years to come. All ITR-ETR schemes enable finer divisions of address space than BGP, and therefore enable the provision of multihomable address space in increments suitable for a large number of end-user networks who don't need hundreds or thousands of addresses. By the time the ITR-ETR scheme is implemented, there will be a huge demand for better utilization of IPv4 address space. There was recent discussion of this in the "IPv4 shortage, new features and IPv6 inevitability" thread. To most technically inclined Internet folks, the IPv4 address shortage is the biggest problem facing the Net - not so many know about the routing scalability problem. Getting the ITR-ETR scheme developed and implemented ASAP is challenging. I think we could get more widespread support for the new scheme if it has as one of its explicit goals the better utilization of IPv4 space, both for more hosts and for more multihoming (and portable) end-user networks. The routing scalability problem is a slow-burning problem which is sure to burn much faster when the IPv4 address crunch happens, because without an ITR-ETR scheme, there will be increased slicing and dicing with BGP, greatly increasing the growth in the number of advertised prefixes, as people start hacking their larger allocations into smaller pieces - just like rural land being subdivided for suburban house lots. So I see solution to the IPv4 routing scaling problem being tied inextricably to the ability of a new scheme to accommodate large numbers (millions) of mulithomable, portable (and perhaps mobile-capable) end-user networks without each one having their own BGP advertised prefix. I think there was a message from one of the LISP team which supported my view that LISP could be used to increase the utilization of IPv4 space - but I don't recall which message it was. - Robin -- to unsubscribe send a message to rrg-request@psg.com with the word 'unsubscribe' in a single line as the message text body. archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg
- Re: [RRG] Convergence - design-goals-01: IPv4 utiā¦ Robin Whittle