Figure 14: Dhcp External Server; Configuring Subscriber Management - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - BROADBAND ACCESS CONFIGURATION GUIDE 2010-10-12 Configuration Manual

JunosE 11.3.x Broadband Access Configuration Guide
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MAC address. When the E Series router's DHCP external server application is used, all
DHCP traffic to and from the DHCP server is monitored by the router.
The services provided by integrating the E Series router's DHCP external server application
with SRC software are similar to those provided when the DHCP local server is integrated
with SRC software. The router's DHCP external application is used together with other
features of the router to provide subscriber management. For additional information, see
"Configuring Subscriber Management" on page 577.
NOTE: To ensure that DHCP external server with DHCP relay proxy processes
unicast reply packets (such as renewal ACK and NAK packets), you must
configure DHCP external server with the IP address of the DHCP relay proxy's
giaddr. This configuration ensures that DHCP external server processes
renewal ACK packets, which in turn enables the updating of client leases.
Figure 14 on page 520 shows a network that includes an external DHCP server and the
E Series router.

Figure 14: DHCP External Server

In Figure 14 on page 520, the subscriber requests an address from the DHCP server through
the E Series router. All communication between the subscriber and the DHCP server is
monitored by the E Series router. After the subscriber receives an IP address, the subscriber
is able to access the Internet and use the value-added services provided by the E Series
router and by the SAE software. For this to occur, the edge network must be using a DHCP
relay function.
When the subscriber requests an IP address from the DHCP server, the E Series router
performs the following actions:
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
The E Series router views the subscriber as active once the subscriber sends a packet.
The router then performs the following actions:
Processes the subscriber's IP address by using a route map
Extracts the dynamic subscriber interface profile (optional)
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