Flapping Links and OSPF

[njorosam]

Hi all,

I'm using OSFF in my network. I have my primary links via fibre and b/up via leased lines. Whenever there a flapping pri link, my remote site registers as down because OSPF keeps on looking for the best path using the fibre link which keeps on going up n down. Is there away whereby i can switch all traffic to leased line whenever service degrades within the fibre links without having to manually intervene & shut down the offending link?

[Giuseppe Larosa]

Hello Sammy,

OSPF with default timers can take up to 40 seconds to detect that the neighbor is dead.

if the link doesn't go down but it is still up/up the router has to wait for dead-interval timer expiration.

Depending on your IOS image you may think to use OSPF fast hellos that can reduce dead interval to 1 second with subsecond Hello frequency.

see

http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/fasthelo.html

Hope to help

Giuseppe