Re: No one behind the wheel at WorldCom

[Pedro R Marques]

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.