ip unnumbered between 2 ethernet interface

[echuang]

Is this legal?

interface Ethernet0

ip address 10.0.0.2 255.255.255.0

interface Ethernet1

ip unnumbered Ethernet0

This router is directly behind another router 10.0.0.1/24 and I don't want to create another subnet between the router. I was hoping that I could borrow the IP address of Ethernet0 and use it on Etherent1. The subnet of 10.0.0.0/24 would then be on Ethernet1.

Please comment and help. Thank you.

[Richard Burts]

Unfortunately No this is not legal. ip unnumbered is only supported on point to point connections and Ethernet is by definition a multipoint connection.

If the routers are directly connected you could assign a subnet with a /30 mask to minimize the addresses used. But if you want the routers to communicate with each other with IP on that connection they must have IP addresses (and a subnet) assigned.

HTH

Rick