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New Member

EIGRP goes down before line protocol


I am tying to understand this wierd behaviour when a WAN link goes down.

The below logs are from a cisco 7304 router.

Jul 19 08:31:57.704: %DUAL-5-NBRCHANGE: IP-EIGRP(0)  100: Neighbor (POS3/0) is down: holding time expired

Jul 19 08:32:21.124: %LINEPROTO-5-UPDOWN: Line  protocol on Interface POS3/0, changed state to down

Jul 19 13:34:40.276: %DUAL-5-NBRCHANGE: IP-EIGRP(0)  100: Neighbor (POS3/0) is up: new adjacency

Jul 19 13:34:41.204: %LINEPROTO-5-UPDOWN: Line  protocol on Interface POS3/0, changed state to up

If you notice when the interface actually went down, Eigrp hold timer expired before before the Line protocol shows down.

Is this behavior expected. Is there a way to fine tune the Line protocol to go down earlier and that trigger Eigrp, rather than EIGRP hold time expiring which would probably take 15 seconds for a OC3 link, hello time being 5sec.



Re: EIGRP goes down before line protocol

If the goal is to cause EIGRP to notice an unreliable link faster than 15 seconds than the hello/hold timers on that link could be adjusted.  This would need to occur on both sides of the link using the interface level 'ip hello-interval eigrp' and 'ip hold-time eigrp' commands.  Something like the following would cause eigrp to declare the link bad after 3 seconds.

int pos x/x

ip hello-interval eigrp 100 1

ip hold-time eigrp 100 3

### 100 is the AS number


New Member

Re: EIGRP goes down before line protocol

Hello Chris,

Thankyou for your response.

Indeed the Link loss can be identified faster by reducing the hello and Hold timers but we consider 15 sec is ok.

But i was trying to understand how much time a POS interface would actually to identify loss of framing when a link goes down and report a line protocol down on the Log.

In this case it is definitely taking more than 15 secs so thats a lot of time.