Issue with static route with distance metric of 255

Unanswered Question
Jun 5th, 2008

Not so much a problem as it is an observation. Has anyone had a problem creating a static route with a distance metric of 255 being inserted into the routing table? Does anyone know why a static route with a distance metric of 255 might not be placed in the routing table?

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Jon Marshall Thu, 06/05/2008 - 11:27

As far as i know an admin distance of 255 means the route is unreachable so the route will not be inserted into the routing table.


dhardy6786 Thu, 06/05/2008 - 11:33

Thanks Jon. I couldn't track down any information on it, but do you know why you'd ever want to put a route in like that if indeed 255 does make it unreachable?

Jon Marshall Thu, 06/05/2008 - 11:39


To be honest no, nothing really occurs at the moment. I certainly haven't used an AD of 255 but perhaps there are others who may have some input.


Richard Burts Thu, 06/05/2008 - 12:06

Daniel and Jon

It has been a while and I do not remember the details clearly but there was a situation in which we wanted to run a dynamic routing protocol with a router (which we did not control) and we wanted it to receive and process our updates but we did not want to put its routes into our routing table. Of the several alternatives that we considered the optimum choice was to set the Administrative Distance of the routes received from that neighbor to 255 which prevented them from being inserted into our routing table.

And the AD that is used by dynamic routing protocols is the same AD used for floating static routes.

One technical nit: an AD of 255 does not make the network unreachable. It makes the route not trustworthy enough to be inserted into the routing table.

dhardy6786 Thu, 06/05/2008 - 12:16

Thanks for explaining Richard. That makes a lot of sense. I bet that's the answer I'm looking for.

Thanks again.


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