System information

Configuring the CMTS
6-3
4. The DHCP server assigns an IP address to each MTA, CM, or CPE that requested
an IP address by placing the IP address in the (Your IP Address) yiaddr field in
the DHCP packet header. The yiaddr is the IP address to be used by the MTA,
CM, or CPE.
5. The DHCP relay agent removes the MTA, CM, or CPE option and forwards the
DHCP server reply, containing the IP address to the MTA, CM, or CPE.
Follow these steps to configure the DHCP relay option on the BSR:
1. Use the show running-config command in Privileged EXEC mode determine the
DHCP relay function is enabled for the desired cable interface, as shown below:
MOT#show running-config
2. If you need to change or enable the DHCP relay function for a cable interface,
enter the desired cable interface from Global Configuration mode.
3. Use the ip dhcp relay information option command in Interface Configuration
mode to enable the DHCP relay agent to insert a MAC address (Agent Remote
ID) only into a client’s DHCP packet, as shown below:
MOT(config-if)#ip dhcp information option
4. Optionally use the ip dhcp relay information spectrum-group-name command
in Interface Configuration mode to enable the DHCP relay agent to insert the
spectrum group name (Circuit ID) into all of the DHCP packets, as shown below:
MOT(config-if)#ip dhcp information spectrum-group-name
Note: The ip dhcp relay information option command must be entered to
enable the DHCP relay information option function. If the DHCP relay
information option function is not enabled, CMs cannot register and go
on-line.
Note: If a DHCP client on a particular subnet is using an upstream frequency
that is not configured as a member of a spectrum group, the spectrum group
name is not inserted by the DHCP relay agent into the DHCP discover
packet.