Re: BGP as-path access-lists

[michael champion]

The link that they have been giving you describes regular expression notation, but it is hard to see how it applies to routing.   Use  the command "show ip bgp regexp [regular-expression] to see what routes match. This will help you probably more than any tutorial on regular expressions, because regular expressions are not router-specific, and it is sometimes hard to figure out how this apples. However, every AS-PATH is in reality a regular expression, even though it shows up as a sequence of AS numbers in the bgp routing table.   Regards,   MLC       Andre Fecteau <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hello, I have been recently placed in the awkward position of making some changes to our BGP configuration.  The problem is that I understand how bgp works for the main part, but I don't have any information on the meaning of the symbols used in the following as-path access-lists (^, $, _, ., +, (), *).  Could someone tell me what each of them mean?  Could someone also point me to a Cisco page that explains them in detail?  I have been searching and cannot find anything except examples that include these symbols.  Unfortuneately these examples have not helped my understanding.  I have a good idea as to what they probably mean, but I need to know their exact meaning.  It is difficult to manage something you don't have a clear understanding of! ip as-path access-list 1 permit  ^$ ip as-path access-list 4 permit  ^(_6774) +$ ip as-path access-list 10 permit  .*5413$ ip as-path access-list 6 permit  ^ (_3414) + (_2423) +$ HELP!!! Andre