Configuring Subscriber Management With An External Dhcp Server - Juniper JUNOSE SOFTWARE 11.2.X - BROADBAND ACCESS CONFIGURATION GUIDE 7-20-2010 Configuration Manual

JunosE 11.2.x Broadband Access Configuration Guide

Configuring Subscriber Management with an External DHCP Server

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between the subscriber and the DHCP server. After the subscriber receives an IP address,
the subscriber can access the Internet and use the value-added services provided by the
SRC software. The following list describes the various procedures performed in the
subscriber management environment:
Subscriber PC—Requests an IP address from the DHCP server
E Series router
Monitors DHCP traffic between the subscriber and the DHCP server:
Identifies the subscriber's IP address, MAC address, giaddr, and client identifier
Extracts the lease time, creates a shadow lease, and starts its own lease timer
that is associated with the subscriber
Determines the subscriber is active when the subscriber sends a packet after receiving
an IP address from DHCP. The router then:
Processes the subscriber's IP address by using a route map
Extracts the dynamic subscriber interface profile (optional)
The router uses the profile to provide authentication, authorization, accounting,
and address assignment. RADIUS uses the profile to obtain information for the
subscriber's IP interface.
Creates the subscriber's dynamic subscriber interface (DSI)
If the SRC software is configured, the router also alerts the SRC software that the
subscriber's DSI and address exist.
The DHCP external server application continues to monitor all traffic between the
subscriber and the DHCP server, and periodically resets the shadow lease it originally
created when the subscriber first requested an IP address. When the subscriber
disconnects, the shadow lease eventually expires, at which time the E Series router
performs the following:
Deletes the DSI
Alerts the SRC software that the DSI has been deleted
Alerts the SRC software that the subscriber's address has been deleted
SRC software—Provides enhanced services to the subscriber.
To configure subscriber management for clients by using an external DHCP server, as in
Figure 15 on page 569, use the following procedure on E Series routers:
Enable the DHCP external server application.
1.
host1(config)#service dhcp-external
Specify each DHCP server for which to monitor traffic. You can specify a maximum
2.
of four DHCP servers.
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