[nsp] eBGP multipath

Jean-Christophe VARAILLON jcvaraillon at dolnet.gr
Tue Mar 2 09:59:55 EST 2004


Hi

I have some trouble getting multi paths from eBGP into the FIB.

After I used the "maximum-paths 2" command, I cleared all BGP sessions
and then I disabled and re-enabled CEF.

I do get the same subnet from the same AS, but there is only one prefered....

Router-A#sho ip route
-----
*  17.255.232.0/24  10.0.0.50                           0 1111 2222 701 i
*>                          10.0.0.51                           0 1111 3333 701 i
----

... and this is confirmed within the FIB:

Router-A#sho ip route 17.255.232.0 255.255.255.0
-----
Routing entry for 17.255.232.0/24
  Known via "bgp 65001", distance 20, metric 0
  Tag 1111, type external
  Last update from 10.0.0.51 00:40:18 ago
  Routing Descriptor Blocks:
  * 10.0.0.51, from 10.0.0.51, 00:40:18 ago
      Route metric is 0, traffic share count is 1
      AS Hops 3
-----

Here is the config of Router-A:
------
router bgp 65001
 no synchronization
 bgp log-neighbor-changes
 network 192.168.0.0
 neighbor 10.0.0.50 remote-as 1111
 neighbor 10.0.0.50 update-source Loopback 0
 neighbor 10.0.0.50 distribute-list 50 out
 neighbor 10.0.0.50 filter-list 60 in
 neighbor 10.0.0.51 remote-as 1111
 neighbor 10.0.0.51 update-source Loopback 0
 neighbor 10.0.0.51 distribute-list 50 out
 neighbor 10.0.0.51 filter-list 60 in
 maximum-paths 2
 no auto-summary

access-list 50 permit 192.168.0.0 0.0.0.255

ip as-path access-list 60 permit ^1111$
ip as-path access-list 60 permit ^1111_[0-9][0-9]*$
ip as-path access-list 60 permit _701$
ip as-path access-list 60 deny .*
-----------------

Router-A is a cisco 7204, running  the IOS (C7200-P-M), Version 12.2(15)T11.


Any suggestions are very much welcome.

Thank you.
Christophe


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