Routing Question

[Patrick McHenry]

don't know exactly why but, we have many host devices on a legacy VLan with a .9 as their gateway. This is really not good because it is a router on our network that we want to get rid of.  And any traffic that uses that gateway must go though the fa0/0 interface and back through to send traffic outside it's VLAN. The rest of our VLANs devices have the standby address as their gateway from our two core routers. These devices are static so, it wouldn't just be a matter of changing the DHCP scope. My question is this:

Can we assign more than one address to one of our VLAN interfaces and have it answer to both? If not, can you see think of any other option other than hitting every device in the network and changing it's gateway? This is a huge scope /22 mask.

Thanks, Pat.

[cadet alain]

Hi,

You can use secondary addressing on a SVI without any problem.

Regards.

Alain.

[Patrick McHenry]

And devices will respond to both?

[cadet alain]

What do you mean by that?

Alain.

[Patrick McHenry]

I mean, if I assign the VLAN of our core routers with two addresses, will devices with either one of those addresses be routable?

For example:

Our standby ip is .3 and our core1 is .4 and our core2 is .5

If I assign core1 with a secondary address of .9, will devices with the .9 and .4 as their gateway both be routed?

Thanks, Pat.

[esomarriba]

They should be!

[Patrick McHenry]

Other than the added traffic of the devices with the .9 gateway address, are there any caveats that I should be aware of with this type of configuration?

[esomarriba]

If you are going to add a secondary IP address to the SVI on your L3 SW. You will need to add the following: ip dhcp smart-relay to make sure your secondary ip address will get IP Address. (your host)

HTH,

Elyinn.-

[Patrick McHenry]

Thanks for the response but, could you clear that up for me? The VLAN has a DHCP server on that VLAN. It is .10 in the scope. I'm now assuming the DHCP server is giving out addresses with the standby for a gateway and not the .9.

Only statically defined devices have the .9 configured for their gateway. So I don't think I would need the DHCP relay, correct?

Thank, Pat.

[cadet alain · Accepted solution]

Hi Patrick,

You're right.

Regards.

Alain.