Troubleshooting and Verification Tips
Troubleshooting IPv4 ACLs requires some attention to detail. In particular, you have to be ready to look at the address and wildcard mask and confidently predict the addresses matched by those two combined parameters. The upcoming practice problems a little later in this chapter can help prepare you for that part of the work. But a few other tips can help you verify and troubleshoot ACL problems on the exams as well.
First, you can tell if the router is matching packets or not with a couple of tools. Example 22-2 already showed that IOS keeps statistics about the packets matched by each line of an ACL. Additionally, if you add the log keyword to the end of an access-list command, IOS then issues log messages ...
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