reply to aryoba
Re: [Config] ISDN Multisite dialup using OSPF cost issue Hi,
Answers for you queries:-
OSPF is already running with channelized-e1 as primary link
we are trying to add ISDN failover with multisite dialing options.
We have half the branches connected to Primary site over lease line and rest of the branches connected to DR site over lease line as well.
At branches there is lease line and ISDN as backup media.
At Primary datacentre site we have Channelized-e1 and PRi as backup.
Similarly at DR site we have Channelized-E1 and PRI as backup for branches.
our requirement is that when primary branch lease line fails it will dial primary site PRI over ISDN.
If both , branch lease line as well as primary site PRI fails branch should dial DR site PRI.
Attaching the configuration of Primary site router, DR site router and one branch of DR site for your understanding.
Problem we are facing is that though branch lease line is UP isdn call is initiated from the branch router to both primary site as well DR site router adn stays connected.
We have different ospf cost for lease line (Low cost) and ISDN as higher cost already defined but still lease line is not preferred and calls are getting routed thru ISDN.
Sorry for the long delay ... been busy
Looking at your network setup, I would prefer to do the followings:
OSPF Design and Failover Routing
1. Just use one area; area 0.
2. The Area 0 should only include Main and DR sites
3. Branches do not run OSPF; just static routes to either Main or DR sites
4. Branches' lease line have static route with low administrative distance (i.e. the default, which is 1).
5. Branches' ISDN have static route with higher administrative distance (i.e. 5)
6. Set the branches' lease line router interface to have backup interface of the ISDN.
7. By setting up the ISDN interface as backup, the ISDN would be in standby mode and only active when the lease line is down
8. Similarly, there would be static routes on Main and DR sites pointing to branches
9. The static routes would be distributed into the Area 0
10. Static routes to branches over lease line would have low administrative distance
11. Static routes to branches over ISDN would have higher administrative distance
12. Set the Main and DR lease line router interfaces to have backup interface of the ISDN