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I am planning to change the Subnet id /Mask of one of our back up router's interface and I was wondering if that could have any negative impact on EIGRP route and its convergence and if it could stop advertising static routes to other router/switches running eigrp...

Basically I am trying to be proactive to know what to expect and what I am going to see and deal with in order to be prepared and come up with plan B.

Is there anyone that have gone through the same path or any experiences in this regard to share please?




1 Accepted Solution

Accepted Solutions

Is the interface you are changing the one connecting to the rest of the network?

just making sure the ip and mask will match the device on the other end.

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24 Replies 24

Just to be clear you are redistributing static routes with eigrp?

Do you have a network statement for your proposed change?

Is the interface you are changing the one connecting to the rest of the network?

just making sure the ip and mask will match the device on the other end.

yes. it is....

in fact , i do this just to bring them all along within the network including other ends.

I don't see why it would affect the static routes.  As long as eigrp stays up it should redistribute the routes. 

i totally agree but apparently earlier they attempted to change it with no success but i have no clue about  what happened nor the path the took & that is why i am trying to be proactive just in case...

In that case the subnet mask will have to match I believe for eigrp to work.


well... it is working just the way it is now... but i dont know what to expect upon changing the mask and the interface... even though the network statement is gona stay the same but my concern are the static routes...

Chris...given that a few of our subnet mask are not matching with the eigrp s/ mask, what would be the solution? How can i make it work? we have a few vlans and they are running on a different subnet mask, so what do you suggest?


Depending on your design you could add the subnets to the EIGRP configuration if you are planning on using EIGRP for the routing protocol on those subnets.

for instance if one of the networks that isn't matching the eigrp mask is: /24

you could add

router eigrp 2


it's kind of hard to tell given the information,


did you try making the subnet mask change, and it didn't redistribute the static routes?


Yes i did and they didn't get reditributed, it seems i have to add all those subnets (Network Statements) on both swicthes....(Primary too)

ok so on router A

you have static routes

and eigrp configured

and router b has eigrp configured

but you don't see the static routes populating on router b?

i assume the mask for the is /16

what is it changing to?

Basically....i have tested both routers today (mock them on GNS3) and all is working great..static routes are populated and eigrp does its i know the new subnet id and mask works and there is no issue whatsoever on the routers and they are not complaining about any subnet but upon connecting them to our switches they start complaining about two VLANs or IP address that they are on a different subnet and therefore eigrp neighborship never established.

We have three switches and they are all connected to VSS... so now i need to dig through all the configuration per switch to figure it out the possible bad configuration...

Any suggestion?


when you say the switches are complaining, is there an error popping up?

if so what's the error?


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