I have part of my OSPF network running over VPN tunnels. These tunnels run over the internet through separate connections. These links occasionally drop or have momentary packet loss. I would like to change the hello and router-dead intervals on these tunnels to make them switch over faster. Can I make this change without having to change every other router in the whole network? As long as the intervals match on each side of the vpn I should be ok right?

Just checking before I make the change.

The hello and dead intervals only have to match on the interfaces between directly connected peers.

Don't be too zealous. Take into account that link thrashing in the same area leads to the OSPF algorithm being run on every router in the area. And possibly other areas depending on more complex details. If the intervals are too short "normal" network conditions for tunnels can lead to the whole area or AS being unstable.

The hello and dead intervals only have to match on the interfaces between directly connected peers.

Don't be too zealous. Take into account that link thrashing in the same area leads to the OSPF algorithm being run on every router in the area. And possibly other areas depending on more complex details. If the intervals are too short "normal" network conditions for tunnels can lead to the whole area or AS being unstable.

fewi,

Thanks for the response. That's why I was asking, I was afraid of going "too low". Everything is still on default (Hello:10 Router Dead Interval: 40 etc)

What would you recommend as a safe lower setting? I have 7 routers participating in the backbone and more are possible on the horizon. Right now the other areas are just for the pppoe servers. I have A mix of RB450G's, RB493G's RB1100's and 1 RB1200.