Thread: why is it that when I need to phone VM, they fail to deliver?
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Old 10-10-2009, 10:48   #12
Ignitionnet
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Re: why is it that when I need to phone VM, they fail to deliver?
Quote:
Originally Posted by BenMcr View Post
I'm sure Broadbandings will correct me over this - but I wasn't aware that Virgin's DHCP servers worred about the MAC address of what was connected to the modem. I always though it would be down to whether modem is correctly connected as to whether an IP address is issued
Certainly, Virgin's DHCP servers need to worry about what's connected to the modem otherwise none of us would get IP addresses to our equipment we connect to the modem.

The DHCP servers do two transactions for each modem, one providing the modem with its' 10.x IP address for IP level communication and a second transaction providing a public IP address to the device connected to the modem.

The modem directly triggers the first transaction by broadcasting a DHCP discover when it is coming online, it relays the DHCP discover broadcast from the CPE connected to it when that device is trying to get an IP address. The CMTS notes which cable modem this comes from and makes that available to the DHCP server as well as part of the DHCP options.
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