[18835] in North American Network Operators' Group
Re: The Cidr Report
daemon@ATHENA.MIT.EDU (Erik Sherk)
Tue Aug 18 19:23:26 1998
To: "Sean M. Doran" <smd@clock.org>
cc: alex@nac.net, tli@juniper.net, apops@apnic.net, eof-list@ripe.net,
nanog@merit.edu, routing-wg@ripe.net, tbates@cisco.com
In-reply-to: Your message of "Tue, 18 Aug 1998 03:25:03 PDT."
<19980818102511Z27216-27746+40@cesium.clock.org>
Date: Tue, 18 Aug 1998 17:33:00 -0400
From: Erik Sherk <sherk@UU.NET>
> Tli asked:
>
> | Exercise for the reader: If prefixes of length F and longer are filtered,
> | and a domain has a prefix of length N, how many prefixes can they propagate
> | into the backbone? How many before people start proxy aggregating them?
>
> A/ (2 ** F) - 1. [assuming nobody imposes exact-match prefix filters]
>
> B/ When we can easily do:
>
> "router bgp N
> proxy-aggregate route-map Lazy-Types
I may be misunderstanding, but does this (proposed) config statement
automaticly suppress (aggregate) any prefixes that are exactly the
same as another prefix except in the length? For example given
128.8.0.0/16
128.8.0.0/24
128.8.1.0/24
the last two would not be propogated? That would be cool!
Erik
>
> ! exceptions
> route-map Lazy-Types deny 10
> match as-path 100
>
> ! the rule
> route-map Lazy-Types permit 20
> match originated-prefix-count 16"
>
> then the number 16 strikes me as a starting point,
> although I probably want to re-read Dennis's comments
> from a few years ago.
>
> Do I pass?
>
> Sean.
>
