From: Alexander Arsenyev (GU/ETL) (alexander.arsenyev@ericsson.com)
Date: Thu Oct 28 2004 - 05:14:42 GMT-3
Hello,
It looks like You have to differentiate between 2 scenarios:
1. Serial line fails -> BRI should stay down and traffic needs to be rerouted via b/bone
2. Serial line reaches certain load -> BRI should connect and traffic split between Serial and BRI.
Also, if R1 and R2 are running OSPF and "connected to b/bone" it means to me that Serial and BRI are NOT in area 0.
Is it correct? If yes then routes learned from b/bone will always be less preferred (OSPF Inter-area) as opposed
to routes learned directly from OSPF neighbor connected via Serial/BRI (OSPF Intra-area) and rerouting should happen automatically should Serial fail.
Is Serial link running PPP? If yes why not bundle BRI and Serial with PPP Multilink and load-threshold?
HTH,
Cheers
Alex
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Geert Nijs
Sent: 27 October 2004 13:42
To: ccielab@groupstudy.com
Subject: Backup and bandwidth-on-demand
Hi group,
I have two routers R1 and R2 connected via a serial line and ISDN BRI, both running OSPF
Both routers R1 and R2 are also connected to a backbone which runs OSPF.
The ISDN BRI is configured to provide bandwidth-on-demand with the backup interface and backup load commands.
So when the load is high, the BRI kicks in to help the serial line. This works fine.
The OSPF costs over the serial line and BRI line are equal, so that load balancing occurs when both lines are active.
However, in a failure scenario of the leased line, i don't want to run exclusively over the BRI lines (half of the bandwidth).
Actually, if the leased line fails, i don't want BRI backup, but rerouting across the backbone.
The problem is, that due to the backup interface command on the serial line, in case of failure, the BRIs get
activated immediatly and since i am running a routing protocol over the BRIs, the BRIs become the preferred route.
I can't change the cost over BRI since i'll have to change the cost over the serial lines also (to keep them equal for load-balancing).
I have been breaking my head on this issue, but i cannot think of a feature that Cisco provides to overcome this issue.....
So if you have any information, links, hints.....
Regards,
Geert
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