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Heriberto Diaz
Beginner

EIGRP Metric + DMVPN + MPLS

Hi

 

I have a DMVPN configured and EIGRP, when I check the Metric to the IP 192.168.XX.XX I got the next information:

 

Router#sh ip route 192.168.YY.0
Routing entry for 192.168.YY.0/24
Known via "eigrp 111", distance 90, metric 1000106
Tag 31, type internal
Redistributing via nhrp, eigrp 111
Last update from 172.Y1.X5.1 on Tunnel1, 03:48:01 ago
Routing Descriptor Blocks:
* 172.Y1.X5.1, from 172.Y1.X5.1, 03:48:01 ago, via Tunnel1
Route metric is 1000106, traffic share count is 1
Total delay is 1620 microseconds, minimum bandwidth is 30000 Kbit
Reliability 255/255, minimum MTU 1400 bytes
Loading 27/255, Hops 3

 

I did the manual calculation with the EIGRP Formula and I got a different value ¿Does anyone know if I need to consider another value?

 

Metric = 256* (BW+DELAY)

BW = 10^7 / 30000 =  333

Delay = 1620/ 10 = 162

Metric = 256*(333+162) = 126720

 

Thanks and regard

 

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1 ACCEPTED SOLUTION

Accepted Solutions
Kevin Rivest
Beginner

It looks like you are using wide metrics.

 

The correct formula for EIGRP wide metrics would be:

 

Metric = (Delay * 65536)/10^6 + (10^7 * 65536)/BW

 

The delay is also expressed as picoseconds in wide metrics and you must divide the final composite metric by the RIB scale which defaults to 128 to get the value inserted into the routing table for the metric.

 

Using your component metrics it would look like this:

 

Metric = (Delay * 65536)/10^6 + (10^7 * 65536)/BW

 

Delay = (1620000000 * 65536)/10^6 = 106168320

 

BW = (10^7 * 65536)/30000 = 21845333

 

Metric = 106168320 + 21845333  = 128013653

 

RIB metric = 128013653/128 = 1000106

 

 

As you can see the wide metric formula produces the correct RIB metric you are seeing based on your composite metrics. 

 

Hope that is clear and helps answer your question.

View solution in original post

4 REPLIES 4
Peter Paluch
Hall of Fame Cisco Employee

Hello Heriberto,

Interesting. Could you please share the following additional outputs from the same router? It is possible that the wide metrics might be playing a role here.

show ip protocols
show eigrp plugins
show ip eigrp topology 192.168.YY.0 255.255.255.0 detail

Thank you!

Best regards,
Peter

Kevin Rivest
Beginner

It looks like you are using wide metrics.

 

The correct formula for EIGRP wide metrics would be:

 

Metric = (Delay * 65536)/10^6 + (10^7 * 65536)/BW

 

The delay is also expressed as picoseconds in wide metrics and you must divide the final composite metric by the RIB scale which defaults to 128 to get the value inserted into the routing table for the metric.

 

Using your component metrics it would look like this:

 

Metric = (Delay * 65536)/10^6 + (10^7 * 65536)/BW

 

Delay = (1620000000 * 65536)/10^6 = 106168320

 

BW = (10^7 * 65536)/30000 = 21845333

 

Metric = 106168320 + 21845333  = 128013653

 

RIB metric = 128013653/128 = 1000106

 

 

As you can see the wide metric formula produces the correct RIB metric you are seeing based on your composite metrics. 

 

Hope that is clear and helps answer your question.

View solution in original post

Peter Paluch
Hall of Fame Cisco Employee

Hi Kevin,

Spot on! Rated as deserved.

Best regards,
Peter

Thank you for you support.

 

Regard.

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