Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

secondary IP address LAN routing

I am trying to re-address my network to use private addressing (10.x.x.x). Would like to apply IP address 10.0.0.1/24 secondary to an ethernet port of 3640 router. Same port already has primary IP address 129.179.100.1/24 (a real address). How can I configure the router to route traffic between these two networks, both on same physical ethernet port? I am not running any routing protocol, using only static routing. Hoping to use this trick during migration period, then change to 10.0.0.1 as primary address when done.

  • Other Network Infrastructure Subjects
4 REPLIES
Cisco Employee

Re: secondary IP address LAN routing

If you assign 10.0.0.1/24 as secondary and 129.179.100.1/24 as main IP address, you dont have to configure any routing protocol to route between these 2 subnets. These are directly connected subnets and will route

New Member

Re: secondary IP address LAN routing

It's good decision when you want to use another mask or network IP address. If IP routing is enable in your router it's enough add secondary IP address on the phisical interface. Everything will work well.

New Member

Re: secondary IP address LAN routing

Assuming you are trying to configure these on Fa0/0. Just these commands would suffice your requirement;

! beginnig of config

!

ip classless

ip routing

interface Fa0/0

ip address 129.179.100.1 255.255.255.0

ip address 10.0.0.1 255.255.255.0 secondary

no shutdown

!

! end of config

Hope this helps.

Rgds,

-SK.

New Member

Re: secondary IP address LAN routing

Thanks to all. Discovered I had caused my own problems by applying access list to the port. Forgot to check it. TAC discovered it. I will remember that one next time.

100
Views
0
Helpful
4
Replies