I am having a problem when attempting to configure sub-interfaces for a Frame Relay connection and was wondering if anyone has ever seen this problem before. I configured two routers for a point-to-point Frame Relay circuit with sub-interfaces and performed a test and turn-up with AT&T which worked fine. The problem I am having is I realized after I configured the interfaces on both routers that I had used the wrong IP addresses. I setup both ends of the circuit with a subnet address of 255.255.255.252 but when I attempted to change the address I get a bad subnet mask error. I have both routers configured as IP Classless and was able to assign a /30 address to both earlier. I removed the IP address from the interfaces and tried to add a new address and I get the same thing. Is there something special with sub-interfaces or Frame Relay which is causing this problem? Any suggestions would be greatly appreciated. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=9697&t=9697 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]