Does log-Input noticeably affect network performance?

[richarddowna]

Hello.

Im running IOS version 12.4(20)

Ive been reading that some versions of the IOS will have a noticeable affect on network performance if log-input command is used on an access list.

Is this true for my version of IOS?

I understand logging is going to have some impact. But my router cpu performance usually sits at around 1-5%, and around 60% with heavy traffic.

Is it really going to be noticable?

Thanks

[Richard Burts · Accepted solution]

Richard

I am not clear whether you are asking about the difference of using the log parameter in an access list vs using log-input or are asking about the difference of not logging in the ACL vs logging. There is not any particular difference in performance between log and log-input.

Whenever the access list must generate log output because of any logging parameter (either just log or log-input) there will be impact on the CPU. How much impact depends mostly on how much log output is generated. If your access list is going to generate one log entry per 5 minutes then there would be no noticeable effect. But if your access list is going to generate multiple log entries per second then the impact is obviously greater.

HTH

Rick