Routing in and out the same interface

Answered Question
Mar 21st, 2008

Can a Cisco router route traffic it receives back out the same interface, perhaps destined for another segment and with a different destination header?

Correct Answer by Joseph W. Doherty about 8 years 11 months ago

Secondary addresses, you may have more than once, would allow multiple subnets on the same interface.


If the VLAN trunks are supported, you can have multiple logical interfaces on the same physical interface.

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Joseph W. Doherty Fri, 03/21/2008 - 11:53

Yes it can send traffic out the interface it entered but what level destination header did you have in mind?


Some examples of traffic exiting the inbound interface.


Secondary IP addresses on interface.


Interface IP address, used as gateway address.


(Physically) Different subinterface IP addresses.

attrib7575 Mon, 03/24/2008 - 07:06

I was basically trying to artificially make it as if the router had three interfaces instead of two. That way I could take incoming traffic on one interface, and route it to one of two different subnets. I guess one interface can have a secondary IP address as you mentioned above? Confusing. Thanks for the reply!

Correct Answer
Joseph W. Doherty Mon, 03/24/2008 - 07:25

Secondary addresses, you may have more than once, would allow multiple subnets on the same interface.


If the VLAN trunks are supported, you can have multiple logical interfaces on the same physical interface.

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