eigrp & mppp

[jsalminen]

I have three routers in a full mesh point to point architecture. Two of the three routers have an extra T1 that is bound to another T1 under MPPP. In my routing table this MPPP circuit is selected as a feasible successor to each of these two routers because the composite metric is higher than the lone T1 metric. The metrics are close, but the T1 (even though there are two hops) is lower by a few hundred digits. I have found that the serial interfaces delay is steady at 2000ms and the multilink interface is steady at 10000ms. Unfortunately, this 10000ms delay is putting my MPPP composite metric out of wack and thusly making it a feasible successor to other routes.

My questions are:

Serial interfaces seem to default to 2000ms delay, why does a multilink interface which has two serial interfaces bound to it have 5 times the serial interface delay? Can I manually override the multilink delay to a more realistic delay like 4000ms? If this cannot be done I cannot use multilink PPP because of this exceptionally high delay value. Is IP CEF a viable candidate in this situation?

Thanks in Advance!!

[donewald · Accepted solution]

The inteface "delay" command will allow you to over ride whatever EIGRP is picking as the delay. EIGRP, in my experience, will lesson the delay in a Multilink interface as links are added, so your problem might be due to configuration / defect / etc??? Delay syntax is the following:

VXR1(config-if)#delay ?

<1-16777215> Throughput delay (tens of microseconds)

You can enable CEF and still achieve your desired results and reduce router CPU from switching functions.

Hope this helps you,

Don

[jsalminen]

Thanks for the tip. By the way, do you know of a document that lists all the IOS interfaces and their default delay values? Does the delay value fluctuate in a live network?