What happens if you...

[1Drisnil]

Uisng a Cisco Router with IOS 12.2 or higher, what happens if you add "no Keepalive" command to a serial interface?

I understand you can safely add this command when programming an ethernet interface, but I was under the impression you should avoid adding that command to serial interfaces. Is this true? Why is this the case?

Inquiring Minds,

 

[jimmyzz]

weijinu,
Consider keepalives to be like a "heartbeat" for you interface. If the router does not recieve a keepalive signal for the interface within a certain time, it will think that the connection for that interface has been disconnected and will change the state of the interface to be "down".

On serial interface connections such as Frame Relay, the keepalives are generated by the NTU in the form of LMI keepalive. If the NTU is working, and cables are connected correctly, then your router will automatically recieve the keepalives. If you disable keepalives, then you really have no idea if the connection is active as you are forcing the router to think that the serial interface is constantly up.

JimmyZ

 

[1Drisnil]

Ah!

Thank you jimmyzz for clearing that up for me.