Hey ChimpyBoy, Welcome to G2G
What you are describing is both right and wrong. ComCast has nothing to do with it. DHCP (RFC2131) is actually the culprit.
DHCP works like this:
When your computer (DHCP CLIENT) connects to a network (in your case a private lan), it sends a request message to the DHCP SERVER (an actual server or a router) to request an IP address. The DHCP SERVER grabs an IP address from a pool or scope of IP address that it has been configured to work with and associates that IP address with the MAC address for that computer. The IP address it associates has a "lease" period or expiration. while the "lease" is valid every time you connect to the network the DHCP server still reads the MAC address from the DHCPREQUEST and looks up the IP address in its database and ends up just saying "you're still good" and all is fine. When the lease expires, the DHCP SERVER reads the MAC, looks up the IP address and says "um, this is expired" and tries to assign a new IP address.
Your router acts as a DHCP SERVER. On your router config, under DHCP settings, look at the DHCP LEASE TIME, that is the amount of time that your router "keeps" that IP address active for your computer (DHCP uses the MAC address to identify computers). To ensure smooth operation you want to create a "pool" of IP addresses that DHCP can work with. This is accomplished by setting a DHCP START ADDRESS and a DHCP END ADDRESS
DHCP LEASE TIME 1 : 0 : 0 : 0
Days Hours Minutes Seconds
DHCP Start Address 192.168.1.15
DHCP End Address 192.168.1.47
Here I have 32 IP address to work with.
What would happen if it looked like this:
DHCP Start Address 192.168.1.2
DHCP End Address 192.168.1.2
or if there was not even a range of IP addresses configured?
Another possible issue is that some ISPs (especially cable companies) have the DHCP SERVER on their end and they associate an IP address with the cable modem's MAC address. To connect a router in this type of setup you may need to have the router "spoof" the MAC address of the cable modem. or you may need to turn off Use router as DHCP server by unchecking it in the router configuration menu.
Click on this LINK
for support on your router.
Having said ALL that, keep in mind that WIRELESS networking is at best an "open-proprietary standard" . If you have a netgear router for best results use a netgear card. Different vendors still don't always 'habla' each other that well yet....
Edited by brianmil0923, 28 September 2005 - 12:46 AM.