Subject: [USR-TC] ARC OSPF adjacency problem with Backup DR

From: Antonio Querubin <[email-masked]>
Date: Sat, 09 Feb 2002 05:53:03 +0000

In a single TCS chassis I have 2 HiPerARC router cards.  The TCS is
attached to a network of Cisco and Juniper routers configured in OSPF area
1.  Two of the Cisco routers are configured with a higher OSPF priority
than the other routers and so are the designated router and backup
designated routers.  Previously only 1 ARC (call it ARC1) had been
configured to run OSPF and it had been working well.

When I enabled OSPF on the second ARC (let's call it ARC2), neither ARC1
nor ARC2 could establish an adjacency anymore with the backup designated
router.  Both ARCs establish OSPF adjacency only with the designated
router (Full/DR).  However their state with the backup DR continuously
cycles between Init, ExStart, and Exchange states.

Furthermore, although their state with the primary DR is 'Full/DR', the DR
never sees the routes announced from either ARC1 or ARC2.

At first I thought this might be a problem unique to Cisco but if I clear
the OSPF process on the backup DR, which forces one of the Juniper M5
routers to be elected as a backup DR, the Juniper M5 exhibits the same
symptoms.  Ie. the M5 never establishes OSPF adjacency with either ARC.
However, the Cisco which was previously the backup DR and could not
establish a stable adjacency state with the ARCs now goes into a normal
OSPF 'TwoWay' state with both ARCs.

At this point I'm beginning to suspect that something special needs to be
configured on the ARCs if both are to be running OSPF at the same time.

Has anyone encountered such a problem and what's the general solution?