Enabling Dhcp Relay Proxy; Use The First Offer From A Dhcp Server; Set A Timeout For Dhcp Client Renewal Messages; Managing Host Routes - Juniper JUNOSE SOFTWARE 11.0.X - BROADBAND ACCESS CONFIGURATION GUIDE 4-1-2010 Configuration Manual

NOTE: The E Series router configured as a DHCP relay proxy must be the first hop
from the DHCP client. If it is not the first hop, the router defaults to the DHCP relay
configuration.

Enabling DHCP Relay Proxy

Enable DHCP relay proxy and specify an IP address for the DHCP server. After you
are in DHCP relay proxy mode, all set dhcp relay commands are supported.
When you issue this command, the router adds the IP address to the list of DHCP
servers (up to five) and forwards all request packets to all configured servers.
After you are in DHCP relay proxy mode, all set dhcp relay commands are supported.

Use the First Offer from a DHCP Server

You can configure the DHCP relay proxy to use the first offer it receives from any
configured DHCP server and send that offer to the DHCP client. By default, DHCP
relay proxy sends the most appropriate offer it receives from the configured DHCP
servers to the DHCP client.

Set a Timeout for DHCP Client Renewal Messages

You can set the amount of time, in the range 1–168 hours, that the DHCP relay proxy
waits for a renewal message from DHCP clients after a router reboot or switchover
occurs. A renewal message is required from DHCP clients when a router reboot or
switchover occurs. If no renewal message is received before the timeout expires, the
relay proxy declares the client no longer active and removes the client's host route
By default, DHCP relay proxy uses timeout of 72 hours.
NOTE: DHCP relay proxy does not remove a DHCP client's host route when the lease
for the client's IP address expires. DHCP relay proxy will instead remove the host
route when the relay proxy timeout expires. To prevent a host route from remaining
long after lease expiration, modify the relay proxy timeout from its default setting
of 72 hours to a setting close to, but not less than the lease time.

Managing Host Routes

The DHCP relay proxy feature enables the E Series router to efficiently manage host
routes for DHCP clients, including:
host1(config)#set dhcp relay 192.168.29.10 proxy
host1(config)#set dhcp relay proxy send-first-offer
host1(config)#set dhcp relay proxy timeout 8
Installing routes when DHCP clients are configured
Chapter 20: Configuring DHCP Relay
Configuring DHCP Relay Proxy
513