I am an Admin for a small Cable ISP. We have grown to a point where we need another block of IP addresses for our cable modems. Our modems, CMTS and TFTP Server run on a private IP block 172.31.1.1-254. Now that we need another block of IPs I am somewhat stumped as to where to make the changes to accomodate the new block.
Problem:
CMTS, modems and TFTP server all are on 172.31.1.1-254 block. When I put in another interface to accomodate 172.31.0.1 block the TFTP server refuses or discards packets from both blocks. I will also list the equipment and software we are using. The CMTS is an Arris/Nortel CMTS 1000. The software for provisioning the modems is DOCSIS LANCity 2.0. The TFTP Server is called Server Control by FTP Software. The machine I am using to authenticate the modems on is a Windows 98 box. I think the problem lies either in the CMTS gateway or the TFTP server. There is no place to specify that the TFTP server software use a multi-homed server and I think it may be getting confused when I add another IP subnet to the computer that is running the TFTP server.
Any help or ideas would be greatly appreciated. I have a line of new customers waiting and I am pulling my hair out trying to figure out what I am doing wrong. Thank you in advance. :?:
I have found a solution to this problem. I will post it here in case someone else can benefit from it. The CMTS, modems and TFTP server all need to have a 255.255.254.0 subnet mask. This allowed me to use a 172.31.0.1 block with our existing 172.31.1.1 block. All I was missing was changing the subnet mask on our CMTS. Case closed.