Hey Pete, Thanks for the explaination. It does make sense now!
There were two things I was not aware of: 1) Routers prefers the EBGP routes due to E vs I preference 2) You are only allowed to advertise your best path for a particular NLRI I went back to my books and tried to find references on the first point. This is what I found: (Doyle, TCP IP vol2 : page 115) 1) Prefer path with the highest administrative weight 2) Prefer path with highest Local_Pref value 3) Prefer path originated locally i.e. from an IGP 4) Prefer path with shortest AS_Path 5) Prefer path with lowerst origin code 6) Prefer path with lowest multi_exit_disc value 7) Prefer EBGP paths over IBGP path 8) Prefer path with shortest path to bgp next_hop 9 install equal-cost routes in the Loc-RIB (maximum-path enabled) 10)prefer path with lowest BGP router ID (maximum-path not enabled) There is no mention of EBGP path versus IBGP. Worse, if I was to go by the rules above I would have to conclude that R4 should have chosen the path via AS102 because of the highest LocPref. (see below) R4>sib BGP table version is 3, local router ID is 192.168.250.4 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 172.16.0.0 10.10.4.2 0 100 101 i * i 10.10.2.1 100 0 102 101 i There must be a set of rules out there that precede the rules above ... Where did you learn about those? Are they published some place? Thanks, Pierre-Alex Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=51202&t=51169 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
