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pablitomassa82
Beginner

OSPF + SDH + BFD Question/Problem

UPDATED!!!! (in this version i explain more accurate scenario)

 

Hi Everybody,

I have this scenario:

Router 1 is connected with Router 2 through an ethernet cable and Router 2 is connected with Router 3 through SDH devices as shown in the picture below. OSPF is enable in all the interface of all Routers.

 

1.PNG

 

All the interfaces are UP-UP and and OSPF works correctly (Router 1 can ping Router 3).

If the links between two SDH goes down the Router 2 and Router 3 doesn't notice of it and their interfaces remains in UP-UP state. In this situation OSPF works incorrectly because Router 2 see that it's fa0/1 interface are still UP-UP and advertise the connected network 10.0.0.0. Router 1 choose to reach Router 3 passing trough Router 2,  but now Router 1 can't ping Router 3 due to link faliure.

 

 

2.PNG

 

 

Is that the case to implement BFD protocol between Router 2 and Router 3 to trigger OSPF interface when the link between SDH goes down?

Thanks a lot

Paolo

 

1 REPLY 1
pablitomassa82
Beginner

To resume:

Is this scenario, when SDH link fails is better:

1) That interface fa0/1 of Router 2 and Fa0/0 of Router 3 remains UP

2) That interface fa0/1 of Router 2 and Fa0/0 of Router 3 goes DOWN

 

I think it's better the Option 2 because prevents strange OSPF behavior. So there is a way to trigger down the interface fa0/1 of Router 2 and interface fa0/0 of Router 3?

thanks a lot