Re: [Idr] WGLC on draft-ietf-idr-as-private-reservation-00

[Warren Kumari <[e-mail]>]

On Dec 12, 2012, at 4:08 PM, Nick Hilliard <[e-mail]> wrote:

> On 12/12/2012 18:52, Brian Dickson wrote:
>> Okay, in as-plain, here goes:
> 
> ah, thanks - that's saved me the bother of sitting down and exercising the
> grey matter of an evening.  In fact you can optimise it by taking
> characters out from the front, which I've done below.  On some systems with
> recursive RE libs, you can do more of this and shorter the RE string.  On
> other RE libs which support specifying the atom instance count, you can
> replace sequences of dots with squiggly braces, but that won't help much
> with readability and it's not portable across all of the various vendor
> regexp libs (and it will just make it look like modem-induced line-noise).
> I've taken out the 42 and cut-n-pasted it into a cisco router, and it now
> looks like this:
> 
>> ip as-path access-list 499 permit _42(781900[8-9].|78190[1-9]..|7819[1-9]...|78[2-9].....|79......|8.......|9[0-3]......|94[0-8].....|949[0-5]....|9496[0-6]...|94967[0-1]..|949672[0-8].|9496729[0-4])_
> 
> It will be similar but not the same on other vendors.
> 
> If we aim for a decimal-aligned system, in the worst case this is reduced to:
> 
>> ip as-path access-list 499 permit _XXX......._
> 
> ... for some simple numeric value of XXX.
> 
> I know which regular expression I'd prefer to deal with.

Sure, but *you* have the ability to use (by policy)  4,280,000,000 to 4,289,999,999 within your network and then your regexp becomes:
ip as-path access-list 499 permit _428...…._

Personally I think that human readable is much more friendly, but I can see both sides of the argument…

Actually, for yet more fun in this thread, the draft could suggest reserving on the bit boundary, and then another reservation within that that folk would actually allocate from (or just recommendations that folk start counting at 4,280,000,000).

Runs away again, giggling even louder… 
W

> 
> Nick
> 
> 
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