[50039] in North American Network Operators' Group
Re: No one behind the wheel at WorldCom
daemon@ATHENA.MIT.EDU (Pedro R Marques)
Tue Jul 16 04:26:35 2002
Date: Tue, 16 Jul 2002 02:25:49 -0700
From: Pedro R Marques <roque@sbcglobal.net>
To: Vadim Antonov <avg@exigengroup.com>
Cc: nanog@merit.edu
Errors-To: owner-nanog-outgoing@merit.edu
Vadim Antonov wrote:
>On Mon, 15 Jul 2002, Pedro R Marques wrote:
>
>
>
>> From a point of view of routing software the major challenge of
>>handling a 256k prefix list is not actually applying it to the
>>received prefixes. The most popular BGP implementations all, to my
>>knowledge, have prefix filtering algorithms that are O(log2(N)) and
>>which probably scale ok... while it would be not very hard to make
>>this a O(4) algorithm that is probably not the issue.
>>
>>
>
>Mmmm... There's also an issue of applying AS-path filters which are (in
>cisco world) regular expressions. Although it is possible to compile
>several REs together into a single FSM (lex is doing exactly that), I'm
>not sure IOS and/or JunOS do that.
>
>--vadim
>
>
>
>
My comment implied 'prefix-lists' which i believe was what the original
poster refered to. Assuming that the primary key is a prefix, i believe
all major implementations can perform this efficiently. I do agree with
you that whenever the intended primary key is something else most
implementations do not have an efficient way of expressing this.
Route-maps and policy-statements in Juniper-parlance are sequentially
evaluated, rule by rule.
I would still contend that the number 1 issue is how you do express the
policy to the routing code. One could potentially attempt to recognise
the primary key is a route-map/policy-statement and compile it as you
suggest.
It is an idea that ends up being tossed up in the air frequently, but
would that solve anything ?
Is there the ability in the backend systems to manage that effectivly
and if so is text interface via the CLI the most apropriate API ?
regards,
Pedro.
