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Re: What is the most standard subnet length on internet


From: Grzegorz Janoszka <Grzegorz () Janoszka pl>
Date: Tue, 23 Dec 2008 14:49:00 +0100

Nathan Ward wrote:
Let me rephrase; Are there people who are filtering /24s received from
eBGP peers who do not have a default route?

of course.

Curiously, it was really meant as a rhetorical question where the answer was "no".

Why are people doing this? Are they lacking clue, or, is there some reasonable purpose?

Memory mostly I think. /24 prefixes are ~ the half of all prefixes, but they cover only a small percent of the address space. If your router has > 6 full BGP sessions, you can filter /24 on half of them, your memory usage will drop significantly.

--
Grzegorz Janoszka
Leaseweb


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