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How to prevent a router from sending out ICMP messages

glebpe185
Beginner
Beginner

Hi guys,

Just wondering if I can somehow to stop my router to send out ICMP "administratively prohibited unreachable" message when icmp packet are being blocked by ACL.

Don't want my router to waste it's CPU resources.

Thanks a lot.

Gleb.

2 Accepted Solutions

Accepted Solutions

Raju Sekharan
Cisco Employee
Cisco Employee

Hi

configure " no ip unreachables" on the interfaces. This will disable sending icmp unreachable messages

Thanks

Raju

View solution in original post

Hi

It is similar to packets getting process switched.

It can lead to high CPU if you receive lot of such packets which requires to send "icmp unreachables"

Thanks

Raju

View solution in original post

3 Replies 3

Raju Sekharan
Cisco Employee
Cisco Employee

Hi

configure " no ip unreachables" on the interfaces. This will disable sending icmp unreachable messages

Thanks

Raju

Just curious....how processor intensive is this to send a simple "administratively prohibited unreachable" message?

Hi

It is similar to packets getting process switched.

It can lead to high CPU if you receive lot of such packets which requires to send "icmp unreachables"

Thanks

Raju

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