Juniper JUNOSE 11.1.X - BROADBAND ACCESS CONFIGURATION GUIDE 6-4-2010, Руководство по настройке

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In Figure 15 on page 585, the subscriber requests an address from the DHCP server.
The E Series router DHCP external server application monitors all DHCP
communications 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:
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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
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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
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SRC software—Provides enhanced services to the subscriber.
Configuring Subscriber Management with an External DHCP Server
To configure subscriber management for clients by using an external DHCP server,
as in Figure 15 on page 585, use the following procedure on E Series routers:
1.
Enable the DHCP external server application.
host1(config)# service dhcp-external
586 ■
Subscriber Management Procedure
JUNOSe 11.1.x Broadband Access Configuration Guide