Relaying Dhcp Packets That Originate From A Cable Modem; Configuring Relay Agent Option 82 Information - Juniper JUNOSE SOFTWARE 11.2.X - BROADBAND ACCESS CONFIGURATION GUIDE 7-20-2010 Configuration Manual

JunosE 11.2.x Broadband Access Configuration Guide

Relaying DHCP Packets That Originate from a Cable Modem

Configuring Relay Agent Option 82 Information

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You can use the DHCP vendor class identifier option (option 60) to configure DHCP relay
to relay DHCP packets that originate from a cable modem to an external DHCP server
that provides the cable modem with the configuration it requests.
Configure the vendor class identifier option to match the string used by cable
modems—DHCP relay then forwards the packets to each DHCP server that you configured
with the set dhcp vendor-option command (these servers are also considered to be
cable-modem DHCP servers).
To relay DHCP packets from a cable modem:
host1(config)#set dhcp relay
host1(config)#service dhcp-local equal-access
host1(config)#set dhcp vendor-option equals docsis relay 192.168.1.1
host1(config)#set dhcp vendor-option equals cablemodem relay 192.168.1.1
Use the show dhcp summary and show dhcp vendor-option commands to display
information about the cable modem DHCP relay configuration. See "Monitoring and
Troubleshooting DHCP" on page 525.
You can specify the type the relay agent option 82 information that the router adds to
DHCP packets before it relays the packets to the DHCP server. You can use one of the
following keywords to add either the hostname or virtual router name to the front of the
Circuit-Id field or to strip the subinterface ID from the Interface-Id field:
hostname—Adds the router's hostname to the front of the Circuit-Id field; a colon
separates the hostname from the circuit information
vrname—Adds the router's virtual router name to the front of the Circuit-Id field; a
colon separates the virtual router name from the circuit information
Use the exclude-subinterface-id to strip the subinterface ID from the Interface-Id field.
When the interface ID is constructed, it contains the slot/port numbers, the subinterface
ID, and the VPI/VCI for ATM interfaces or the VLAN ID for Ethernet interfaces. Use this
keyword to remove the subinterface ID from the Interface-Id field.
The hostname and vrname keywords are a toggle; that is, specifying either hostname
or virtual router name turns off the other selection.
To configure the relay agent option 82 information:
host1(config)#set dhcp relay options hostname
relay to 192.168.15.2 (rx: 0)
local-server (rx: 0, no-match: 0)
relay to 192.168.7.7 (rx: 0)
Copyright © 2010, Juniper Networks, Inc.