RE: ACL's: Even/Odd -- allow EVEN

From: Sage Vadi (sagevadi@yahoo.co.uk)
Date: Wed Feb 12 2003 - 07:22:54 GMT-3


All,

Receive the following RIPv1 routes (ingress).

198.5.51.0 in 1 hops
198.5.52.0 in 1 hops
198.5.53.0 in 1 hops
198.5.54.0 in 1 hops

Want to permit only the EVEN networks. My calculation
as follows:

52 = 00110100
54 = 00110110

Accordingly we have to do an inverse mask that matches
on the LAST bit (even numbers). That is what I have
done and tested on a subnet calculator (it seems to
bring out the correct addresses).

Hence -

permit ip 198.5.0.0 0.0.254.255 any

Would permit ALL even networks (til 254). Which is
fine, I don't care how speficic.

Q) When I apply this inbound on my egress interface
where I'm receiving this routes - it just doesn't
work?!?!

What stupid thing am I doing? I feel like bashing this
monitor...

rgds,
Sage



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