subnet mask of a loopback int.

shadowman724 · ‎09-27-2006

hi,

can a loopback interface have a subnet mask other than 255.255.255.255 ?

pciaccio · ‎09-27-2006

Yes.. However it is a waste of addresses having a subnet other then /32. You can have any mask on a loopback that you want..Please rate...

Richard Burts · ‎09-27-2006

I agree with Phil that you can put any valid subnet mask on a loopback interface. Whether it is a waste of addresses depends on what you are attempting to accomplish. For example I have configured routers to function as dial access servers and for this I need a pool of addresses. I wish for my routing protocol to advertise the pool of addresses as a subnet rather than as individual /32s. So I configured the address of the subnet with appropriate subnet mask on a loopback interface and have the routing protocol advertise that. It is useful and not a waste.

HTH

Rick

HTH

Rick

gpulos · ‎09-27-2006

i agree with rburts here.

using vlsm or classful subnet masks, other than all \32, allows you the ability to perform dynamic routing functions for the 'group' of loopbacks vs. static routing for each of them.

in some cases, the routing of loopbacks may be required and entering in many individual \32 routes may not be optimal or easily accomplished.