[c-nsp] OSPF default wont originate with default from ibgp

Dean Smith dean at eatworms.org.uk
Fri Jun 24 14:22:53 EDT 2011


bgp redistribute-internal

See :-
http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a0080094
9e8.shtml#twenty-four



-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Eric Morin
Sent: 24 June 2011 18:36
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] OSPF default wont originate with default from ibgp

Short question: Should a default from iBGP trigger a default into ospf if
the (ospf) originate command is conditional on a default in the table?
Documents say 'bgp', but what I am seeing is that a default from ibgp wont
trigger it, but a default from ebgp will.... Is this correct behaviour or I
am missing something, or maybe a bug.. (4948 12.2(50)SG1)? 

 

Longer description/explanation:

 

I have two access routers and two core routers in a square config. The
access routers need to run ospf to support access platforms downstream, but
upstream of the access router (facing core routers) I have ISIS for loop
connectivity and meshed ibgp between core and access routers.
Access routers have bgp network statements for OSPF routes. The access
routers are only getting a default from core routers via iBGP. 

I want the access routers to both originate a default into ospf and then use
the iBGP default to get to the core routers with full tables. On the access
routers I have the (AD) distance for ospf set to 205 (ibgp +5) so access
routers install the ibgp def route instead of the ospf def coming from other
access router, otherwise when both access routers are originating a default
they install each other's default and it loops.

 

For some reason I cant get the access router to originate the default into
ospf once it has the iBGP default in the RT. When ibgp session replaced with
ebgp session it triggers the ospf default, of course, the 'always' statement
in ospf originate command triggers it as well. I have read that a 'bgp' def
route will satisfy ospf's condition to have a default before it originates,
but cant get it to trigger. What could I be missing? Could it that it
doesn't like the iBGP default (vs eBGP)?

 

Thanks in advance for any advice/guidance

Eric

 

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