You can also use the cable dhcp-giaddr command in cable interface configuration mode to modify the
GIADDR field of DHCPDISCOVER and DHCPREQUEST packets to provide a relay IP address before
packets are forwarded to the DHCP server. Use this command to set a
“
policy
”
option such that primary
addresses are used for CMs and secondary addresses are used for hosts behind the CMs.
Note
Configuring the System Default Policy
Add these options to the system default policy for:
•
Cable modems to support on your network
•
PCs to support behind each cable interface on your network
Cable Modems
Define these settings following the CNR tool documentation:
•
TFTP server (IP address) for those cable interfaces using BOOTP
•
Time-server (IP address)
•
Time-offset (Hex value, 1440 for Eastern Standard Time)
•
Packet-siaddr (IP address of CNR)
•
Router (set to 0.0.0.0)
•
Boot-file (name of .cm file for those cable interfaces using BOOTP)
•
Packet-file-name (.cm file name)
PCs
Define these settings following the CNR tool documentation:
•
Domain name
•
Name servers (IP address of DNS servers)
Creating Selection Tag Scopes
General
When you create your scope selection tags:
Cisco cBR Series Converged Broadband Routers Application
—
Voice and Video Configuration Guide
48
Cisco Network Registrar for the Cisco CMTS Routers
Configuring the System Default Policy