I forgot one other thing, that is Chapter 7 of the Second Edition of Halabi's book. I don't remember if all the Chapter numbers stayed the same between the two editions. It has an excellent section on bgp regular expression starting on page 184. Good luck! ""Bill Carter"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I'm having trouble with this AS-Path situation. I have 2 routers (A and B) > running iBGP to each other. > > Each router has a single eBGP connection to a different service provider. > > ISP-A ISP-B > | | > A-------B > > From ISP A I am receiving partial routes, basically network within its AS. > > From ISP B I am receiving full internet routes. > > Here is the problem: The partial routes from ISP A are summarized, and the > routes from ISP may not be summarized. So my router A has an entry for > 12.0.0.0/8 and the AS path has 1 entry. Router B > receives the 12.0.0.0/8 through iBGP and also more specific routes from > ISP-B (12.20.1.0/24, 12.96.0.0/16). In router B the 12.X.X.X BGP entries > have the ISP-A AS# as the first entry in the AS-Path. > > Router B, because of the longest match rule, prefers the Router B-->ISP B > path for the more specific networks. > > I would like to use IP as-path filters to filter incoming updates from ISP-B > so not to learn networks originating from ISP-A AS#. > > What is the regular expression to do this?? > ip as-path access-list 20 deny ?????? ^as#_ _as#$ > > > From sho ip bgp > Network Next Hop > *> 12.0.0.0 A.A.A.A NEIGHBOR > *> 12.0.48.0/20 B.B.B.B NEIGHBOR > *> 12.0.252.0/23 B.B.B.B NEIGHBOR Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=16081&t=16068 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
