Re: [rrg] draft-narten-radir-problem-statement-05.txt

"Joel M. Halpern" <> Thu, 25 February 2010 20:38 UTC

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Date: Thu, 25 Feb 2010 15:40:49 -0500
From: "Joel M. Halpern" <>
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Subject: Re: [rrg] draft-narten-radir-problem-statement-05.txt
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Thank you for responding Thomas.  I don't think what you propose is 
sufficient.  (More after your comments, for context.)

Thomas Narten wrote:
> Hi Joel.
> Thanks for the comments.
>> Thomas, one major and some minor comments on the document.
>> The discussion of IPv6 routing table size in section 4.6 seems 
>> misleading.  The discussion seems to have no component to represent the 
>> present and increasing demand for PI addresses in order to support 
>> multi-homing and ease of renumbering.  If we do not have a routing 
>> architecture and system which addresses those pressures, and if we do 
>> not manage to keep in place an artificial barrier to such PI 
>> assignments, the size of the tables will grow dramatically.  Some 
>> stimates place the expected number of multiohomed enterprises in the 
>> ballpark of 10,000,000.  That would represent a significant growth in 
>> the control plane, the RIB, and the FIB.
> This section was intended to simply point out that dual stack adds
> even more routes, in the sense that one will need both IPv4 and IPv6
> route to the same destination. That only further increases the overall
> number of entries a router deals with.
> It goes without saying (and looking back, the document doesn't say
> this) that all the  pressures that apply to IPv4 routing, apply pretty
> much equally to IPv6.
> Seems to me, that the best way to deal with that is to add a new
> paragraph (perhaps in the introduction) that calls this out
> explicitely. I.e., something like:
>    Most of this document does not distinguish between IPv4 and
>    IPv6. The overall routing archtecture for the two protocols is the
>    same. Consequently, most of the issues in this document apply
>    equally to IPv4 and IPv6. Any behavior that places pressure on IPv4
>    routing is likely to also exert the same pressure on IPv6.
>    Deployment of IPv6 will not lessen these pressures in most cases.

What you propose to add is good.  But, the text in 4.6 as written claims 
"It is possible to extrapolate what the size of the IPv6 routing table 
would be if wide spread adoption of IPv6 occurred..."  Unfortunately, 
the extrapolation that then takes place assumes that the same factors 
that currently constrain IPv4 sizes would constrain IPvb6 sizes, and 
that seems extremely unlikely.  Hence, this extrapolation is very 
optimistic, and misleading to the reader.