09-10-2010 09:35 AM - edited 03-04-2019 09:43 AM
Hi expert,
How can I count the actual IP range of below prefix list
ip prefix-list abc seq 10 deny 10.100.64.0/18 ge 24
ip prefix-list abc seq 20 permit 10.100.0.0/16 ge 24
ip prefix-list abc seq 30 deny 10.100.0.0/14 ge 16
ip prefix-list abc seq 40 deny 10.104.0.0/13 ge 16
ip prefix-list abc seq 50 deny 10.112.0.0/13 ge 16
ip prefix-list abc seq 100 permit 0.0.0.0/0 le 32
09-10-2010 12:19 PM
Not sure what your question is.
You have a list of prefix lists each one with different instructions.
You want to know which IP ranges are matched by the permit statements? Please clarify.
Federico.
09-10-2010 09:38 PM
Yes, you are right
Thank you!
09-12-2010 12:10 PM
Hi,
ip prefix-list abc seq 10 deny 10.100.64.0/18 ge 24 is matching any prefix within 10.100.64.0/18 (=10.100.64.0 - 10.100.127.255) but the prefix mask length must be greater or equal /24. Which means 10.100.66.0/24 is matched, but 10.100.66.0/23 is not, e.g.
The deny keyword is inverting the prefix acceptance logic though, i.e., the matching prefixes are being dropped by the router.
ip prefix-list abc seq 20 permit 10.100.0.0/16 ge 24 is matching any prefix within 10.100.0.0/16 (=10.100.0.0 - 10.100.255.255) but the prefix mask length must be greater or equal /24.
For
ip prefix-list abc seq 30 deny 10.100.0.0/14 ge 16
ip prefix-list abc seq 40 deny 10.104.0.0/13 ge 16
ip prefix-list abc seq 50 deny 10.112.0.0/13 ge 16
the logic is similar to the first line.
ip prefix-list abc seq 100 permit 0.0.0.0/0 le 32 is matching any prefix.
BR,
Milan
09-12-2010 08:38 PM
Hi ,
For ip prefix-list abc seq 10 deny 10.100.64.0/18 ge 24, is it means that
Within the IP range 10.100.64.0 - 10.100.127.255
if route is 10.100.64.0 /24, then is match and will be dropped
if route is 10.100.65.0/ 24, then is match and will be dropped
if route is 10.100.67.0/ 26, then is match and will be dropped
if route is 10.100.64.0/ 22, then is not match and will not dropped
if route is 10.100.72.0/ 22, then is not match and will not dropped
09-12-2010 09:59 PM
Hi,
yes, correct.
This line does not match it.
The final dropping/accepting depends on the following prefix-list lines finally.
BR,
Milan
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide