ip prefix-list

From: ccie2be (ccie2be@nyc.rr.com)
Date: Tue Jan 11 2005 - 19:38:00 GMT-3


Hey guys,

Here's something interesting.

It took me a while, but finally I got it into my head how to create an

ip prefix list ie if you have something like this:

ip prefix-list ALLOW-BGP-IN seq 5 permit 112.0.0.0/5

the slash without being followed by a le or ge means

the prefix must = 112.0.0.0 and the mask must be 248.0.0.0

This also means that 112.0.0.0/8 wouldn't match.

Does everyone agree?

Well, I just came across a scenario which breaks this rule.

I was using the above prefix-list to filter all routes except

112.0.0.0/8
113.0.0.0/8
114.0.0.0/8
115.0.0.0/8
116.0.0.0/8
117.0.0.0/8
118.0.0.0/8
119.0.0.0/8

It worked but based on the rule above it shouldn't have, right?

Can anyone explain why my seemingly "incorrect" prefix-list

allowed those routes?

TIA, Tim



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