Thread: cable modem + switch dhcp problem
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Old 13-06-2010, 17:40   #3
Jon T
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Re: cable modem + switch dhcp problem
VM residential cable modems allocate one WAN/Public IP, they also "bond" themselves to one MAC address. Which in your case in the MAC address of the physical host machine. The only way to force a re-association to a new MAC address it to power cycle the modem during kit swaps.

Connecting your cable modem to your PC via a switch will break the MAC association, as the cable modem will see the MAC address of the switch port that's connected to your cable modem. No point doing this anyway as the cable modem will only talk to one piece of equipment anyway.

Assuming the client and guest OS's NIC's are properly bridged, I suspect your cable modem will need a reboot so that it can associate itself with the MAC of the bridge.

One extra thought: I'm not 100% sure what MAC addy your CM will try and associate to, the MAC of the bridge or the MAC of the physical interface on the host machine, can't remember if one replaces the other.
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