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Beginner

Default-metric in EIGRP

As I am preparing to recertify my CCNP, and am preparing for the route exam, a question came up.

IF a routing protocol, for example OSPF, is redistributed into EIGRP, the metric is defined after "redistribute ospf <process ID>" is configured in the EIGRP AS.

But there is also a "default-metric" command.

Can someone explain why both exist as configurable options in EIGRP?

 

Thank You.

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Cisco Employee

Hi Kevin,

Hi Kevin,

It is purely a matter of comfort. You can define the metric for redistributed in three places:

  1. In the route-map used in the redistribute command, if you are limiting the retaken prefixes using a route-map
  2. In the redistribute command itself
  3. In the default-metric command

When redistributing a route, the router tries to find the appropriate metric to assign in the above ordering - so if you have specified an explicit metric in an applicable route-map block, this will be assigned to the route. If the metric is not specified in the route-map, then the metric specified in the redistribute command will be used, and if that is not configured, either, then finally the default-metric command is used. If not even that one is configured, the route may not be redistributed into EIGRP - be cautious about that. (To be very precise, for static, connected and EIGRP-learned routes, the metric will be retaken from either the outgoing interface or from the original metrics; however, if routes from another routing protocol are retaken, the metric must be specified explicitly.)

Especially when doing a quick-and-dirty redistribution from multiple sources into EIGRP (like, static, connected, OSPF, RIP, ...), it may actually be more convenient to define the redistribution metric just once in the default-metric command, rather than specifying it repeatedly in redistribute statements.

But other than that, there's no much difference.

Best regards,
Peter

View solution in original post

5 REPLIES 5
Hall of Fame Cisco Employee

Hi Kevin,

Hi Kevin,

It is purely a matter of comfort. You can define the metric for redistributed in three places:

  1. In the route-map used in the redistribute command, if you are limiting the retaken prefixes using a route-map
  2. In the redistribute command itself
  3. In the default-metric command

When redistributing a route, the router tries to find the appropriate metric to assign in the above ordering - so if you have specified an explicit metric in an applicable route-map block, this will be assigned to the route. If the metric is not specified in the route-map, then the metric specified in the redistribute command will be used, and if that is not configured, either, then finally the default-metric command is used. If not even that one is configured, the route may not be redistributed into EIGRP - be cautious about that. (To be very precise, for static, connected and EIGRP-learned routes, the metric will be retaken from either the outgoing interface or from the original metrics; however, if routes from another routing protocol are retaken, the metric must be specified explicitly.)

Especially when doing a quick-and-dirty redistribution from multiple sources into EIGRP (like, static, connected, OSPF, RIP, ...), it may actually be more convenient to define the redistribution metric just once in the default-metric command, rather than specifying it repeatedly in redistribute statements.

But other than that, there's no much difference.

Best regards,
Peter

View solution in original post

Highlighted
Beginner

Peter

Peter

Thanks for such a detailed yet easy to understand answer.  Kudos!

VIP Advisor

Hello Kevin I agree  100%

Hello Kevin

I agree  100%



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
VIP Advisor

Hello

Heloo
Eigrp routes are calculated upon these metric msot important Bw/Delay used for best path calcualtion

The default metric (weights) is a catch all - meaning the value you specify here is the default for the entire eigrp routing process

Ospf routes redistributed into eigrp specified with a specific metric will inherit those values upon redistribution.

Editied...

Peter beat me to it

res

Paul



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
Beginner

Paul

Paul

 

I do like your answer "The default metric (weights) is a catch all - meaning the value you specify here is the default for the entire eigrp routing process".

 

Catch-all is the takeaway here.

 

thanks for your response.

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