BGP AS PATH

From: Angelo De Guzman (a.deguzman@wesolv.ph.fujitsu.com)
Date: Thu Aug 31 2006 - 04:50:00 ART


Hi,
  R1 AS 1 peers with R2 AS 24
  R2 peers with R4 AS 24
  R5 AS 256 and R6 AS 256

  R5 peers with R2 in AS 24, and R6 peers with R4 in as 24

  R6 peers to R9 in AS 9

   Both R9 and R1 are advertising the same route.

  When I do as path prepend for the routes coming into R6 (from R9) these
routes dissappears from AS 24.

  Is this normal? If I removed the peering to R1 then the bgp routes comes back.
Any explanation why R4 is not installaing the BGP routes at the same time at
R4? I guess it has something to do with the AS Path but I need more
clarification on this matter.

******NO AS Path prepend at R6 yet*******
R4#sh ip bgp
BGP table version is 5, local router ID is 192.168.4.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf Weight Path
* 10.34.19.0/28 192.168.6.6 0 567 9 i
*>i 192.168.1.1 0 100 0 1 i
*> 10.34.19.0/26 192.168.6.6 0 567 9 i
* i 192.168.5.5 0 100 0 567 9 i
* 10.34.19.32/28 192.168.6.6 0 567 9 i
*>i 192.168.1.1 0 100 0 1 i
*> 172.16.80.0/27 192.168.6.6 0 567 7 8 ?
* i 192.168.5.5 0 100 0 567 7 8 ?
R4#
*Aug 31 15:39:29.746: %BGP-5-ADJCHANGE: neighbor 192.168.6.6 Down Peer closed th
e session
*Aug 31 15:39:29.978: %BGP-5-ADJCHANGE: neighbor 192.168.6.6 Up

**** With AS path prepend at R6*****
!
access-list 1 permit 10.34.19.0 0.0.0.15
access-list 1 permit 10.34.19.16 0.0.0.15
access-list 1 permit 10.34.19.32 0.0.0.15
!
route-map ADDAS permit 10
 match ip address 1
 set as-path prepend 9 9
!
******************************************
R4#sh ip bgp
BGP table version is 8, local router ID is 192.168.4.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf Weight Path
*>i10.34.19.0/28 192.168.1.1 0 100 0 1 i
*>i10.34.19.32/28 192.168.1.1 0 100 0 1 i
*>i172.16.80.0/27 192.168.5.5 0 100 0 567 7 8 ?

****Turning off the R1 peering******
R4#sh ip bgp
BGP table version is 14, local router ID is 192.168.4.4
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf Weight Path
*> 10.34.19.0/28 192.168.6.6 0 567 9 9 9 i
*> 10.34.19.0/26 192.168.6.6 0 567 9 9 9 i
*> 10.34.19.32/28 192.168.6.6 0 567 9 9 9 i
*> 172.16.80.0/27 192.168.6.6 0 567 7 8 ?
* i 192.168.5.5 0 100 0 567 7 8 ?

TIA,
Angelo

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This archive was generated by hypermail 2.1.4 : Fri Sep 01 2006 - 15:41:59 ART