Configuring Loopback Interface for MGMT/MON

[jamesellis]

I am in the process of configuring a loopback interface for mgmt/mon and have a few questions. Also suggestions on best practices would be appreciated.

When assigning the loopback ip address, is it possible to use an address from a segment on an interface? IE, if my fastethernet segment is 192.168.1.0/24, can an address in that range be used on the loopback? Is this a good or bad idea and why?

Is it better to assign a completely different ip network to the loopback interface?

[rsissons]

A loopback interface behaves in exactly the same way as a real physical interface as far as configuring IP addresses on it so, assuming that you are routing IP traffic, it must be in a different IP network to all other interface.

Depending on what routing protocol and addressing scheme you are running however, you can reserve one or more networks for loopback interfaces on all/some of your routers and use a 32 bit mask on the loopback interfaces.