From: David Hurtado (dei2viccie@hotmail.com)
Date: Sun Apr 04 2004 - 08:14:30 GMT-3
Hello everybody,
I have the following situation:
(AS54)
BB1----------------------------------------------------------------------------R6
(AS 100)
54.1.8.254
54.1.8.6
BB1 and R6 are EBGP peers:
BB1:
router bgp 54
neighbor 54.1.8.6 peer-group RACKS
neighbor RACKS remote-as 100
R6:
router bgp 100
neighbor 54.1.8.254 remote-as 54
R6 announces 2 prefixes from its own AS to BB1 (167.1.4.0/24 and
167.1.5.0/24).
From my understanding, R6 should change the next-hop attribute of this
prefixes to its own address (54.1.8.6) when announcing them to BB1.
But what happens is that R6 leaves the next-hop attribute unchanged, so it
points to the IBGP routers that originated the prefixes (150.1.4.4 and
150.1.5.5) so BB1 doesn't accept them.
Here it is the "debug ip bgp update" output from BB1:
Mar 1 06:55:43.122: BGP: 54.1.8.6 Advertised Nexthop 150.1.5.5: Non-local
or Nexthop and peer Not on same interface
Mar 1 06:55:43.122: BGP(0): 54.1.8.6 rcv UPDATE w/ attr: nexthop 150.1.5.5,
origin i, originator 0.0.0.0, path 100, community , extended community
Mar 1 06:55:43.122: BGP(0): 54.1.8.6 rcv UPDATE about 167.1.5.0/24 --
DENIED due to: non-connected NEXTHOP;
Mar 1 06:55:43.122: BGP: 54.1.8.6 Advertised Nexthop 150.1.4.4: Non-local
or Nexthop and peer Not on same interface
Mar 1 06:55:43.122: BGP(0): 54.1.8.6 rcv UPDATE w/ attr: nexthop 150.1.4.4,
origin i, originator 0.0.0.0, path 100, community , extended community
Mar 1 06:55:43.126: BGP(0): 54.1.8.6 rcv UPDATE about 167.1.4.0/24 --
DENIED due to: non-connected NEXTHOP;
BB1 doesn't accept the prefixes because it doesn't have the next-hop
directly connected.
To solve this problem i have to announce R6 as the next-hop:
router bgp 100
neighbor 54.1.8.254 next-hop-self
Then BB1 accepts the prefixes because the next-hop is R6:
Mar 1 07:40:47.686: BGP(0): 54.1.8.6 rcvd UPDATE w/ attr: nexthop 54.1.8.6,
origin i, path 100
Mar 1 07:40:47.686: BGP(0): 54.1.8.6 rcvd 167.1.4.0/24
Mar 1 07:40:47.686: BGP(0): 54.1.8.6 rcvd 167.1.5.0/24
Now everything is fine. But it shouldn't work in this way. It is supposed
that R6 should pass itself as the next-hop by default. Why doesn't it occur
in this way? Could somebody help me to understand it?
NOTE: R6 is a route-reflector-client. I don't think it could be relevant,
but maybe i'm wrong.
Thanks a lot for the help
This archive was generated by hypermail 2.1.4 : Mon May 03 2004 - 19:48:42 GMT-3