Dynamic Routing

Unanswered Question
Jan 30th, 2008

Headquarter and several branch office, Cisco3725 (HQ) anche Cisco-2811 (BO).

WAN connections on Ethernet (transparent bridging over WireLess).

BackUp connection are ISDN-Dialer (DDR Routing).

Dynamic Routing via EIGRP.

No problem in case of TOTAL failure of the "main connection": the EIGRP works very well and the Dial-on-Demand-Routing bring Up the dialer in few seconds.

But in case of poor performances of the "main connection", my EIGRP is not able to follow the degrading and recalculate a new metric, so to switch to the Dialer.

What to do?

Better tuning the EIGRP?

Go to OSPF?




I have this problem too.
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Kevin Dorrell Wed, 01/30/2008 - 03:01

Unfortunately, this is one of the deficiencies of EIGRP. EIGRP looks very useful, with its "load" and "reliability" metrics. In fact, by default, EIGRP ignores those, and just routes according to the delay and path bandwidth.

Even if you adjust the K values so the algorithm takes the "load" and "reliability" into account, you are no better off, because they are not dynamic. The load and reliability are read off the interface when EIGRP starts, and are fixed from then on.

One day they will develop EIGRP that looks at these metrics dynamically, but I'm not holding my breath for it.

Kevin Dorrell


aravindhs Wed, 01/30/2008 - 03:10


That is a very good point you have made.

May be IP SLA could be used.

Performance Routing seems the best choice but would require the right IOS and hence an IOS upgrade on the relevant boxes ..



Kevin Dorrell Wed, 01/30/2008 - 03:18


Thank you for that suggestion - it's a good one.

I am aware that my own posting was rather negative - it presented the problem with EIGRP, but it didn't provide any solutions for the original problem. Sorry :-(

IP SLA sounds a good way to go.

Kevin Dorrell



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