11-18-2015 07:10 AM - edited 03-08-2019 02:44 AM
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.
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11-18-2015 07:27 AM
Hi Kevin,
It is purely a matter of comfort. You can define the metric for redistributed in three places:
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
11-18-2015 07:27 AM
Hi Kevin,
It is purely a matter of comfort. You can define the metric for redistributed in three places:
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
11-18-2015 10:39 AM
Peter
Thanks for such a detailed yet easy to understand answer. Kudos!
11-18-2015 03:12 PM
Hello Kevin
I agree 100%
11-18-2015 07:39 AM
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
11-18-2015 10:38 AM
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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