IP Prefix-List

From: gladston@br.ibm.com
Date: Thu Apr 28 2005 - 17:15:53 GMT-3


Sorry to repeat this topic.
Doing a scenario brought a doubt.

This prefix-list will match 30 first bits and mask /30, right?

ip prefix-list Change-Origin permit 50.180.127.8/30

4th octect -> 0 0 0 0 1 0 0 0
 will check 6 firs bits (more significant to less significant)

50.180.127.8 will pass.
50.180.127.9 would pass but it is not checked (and it is not a network address, it is a host of net 50.180.127.8)
50.180.127.12 will not pass.

Do you agree?

Not getting many help from doc cd:

==========================
quoted

To deny mask lengths greater than 25 bits in routes with a prefix of 192/8:

ip prefix-list abc deny 192.168.0.0/8 ge 25
==========================

So it will allow 192.5.0.0 255.255.255.128.0.
Would you agree?

IOS change this, as if it was not valid:

r5#c
Enter configuration commands, one per line. End with CNTL/Z.
r5(config)# ip prefix-list Change-Origin seq 15 per 192.168.0.0/8 ge 25
r5(config)#do sh run | i ip prefix-list Change-Origin
ip prefix-list Change-Origin seq 5 permit 50.180.123.0/24
ip prefix-list Change-Origin seq 10 permit 50.180.127.8/30
ip prefix-list Change-Origin seq 15 permit 192.0.0.0/8 ge 25



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