Juniper JUNOSE 11.1.X - BROADBAND ACCESS CONFIGURATION GUIDE 6-4-2010, Configuration Manual

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Table 98: Local Pool Selection in Equal-Access Mode
How the DHCP Local Server Uses the Field Field
The client’s entry can be configured with a framed IP address, which the DHCP local server can get from
the SRC software (formerly the SDX software).
If the router selects a pool using a framed IP address, the DHCP local server attempts to allocate the
framed IP address from the pool. If the framed IP address is not available, then the server allocates the
next available address in the pool to the client.
Framed IP address
Each DHCP local pool has a pool name. The client’s entry can also be configured with a pool name, which
the DHCP local server can get from the SRC software. The SRC software must be configured to send
RADIUS attributes to DHCP. Pool name
You can use a domain name as the name of a DHCP local pool. If the client logs onto the SRC software
and RADIUS authenticates the client using a domain name, the DHCP local server receives the domain
name from the SRC software.
If the client’s domain name does not match the name of the DHCP local pool, the router attempts to
match the client’s domain name to the domain name field within the pool.
Domain name
A DHCP local pool is configured with a network address. A gateway IP address (giaddr), which indicates
a client’s subnetwork, can be presented to the DHCP local server in the client’s DHCP request message.
The giaddr field in the DHCP request message contains the IP address of a DHCP relay agent. The router
attempts to match the giaddr address in the DHCP request message with the network address of a DHCP
local pool. Giaddr
The router uses the IP address of the interface on which the DHCP packet is being processed and attempts
to match it with the network address of a DHCP local pool. If the interface address matches with the IP
address configured in the DHCP local address pool on the router, that pool is used to delegate the address
to the client. Received interface
IP address
The Connection Process
The following sequence describes how the subscriber connects to the network for
the first time using equal-access mode. Figure 11 on page 472 illustrates the process.
1.
The subscriber’s computer boots and issues a DHCP request.
2.
The DHCP local server uses the SRC client to issue a COPS request to retrieve
address pool information.
3.
After standard DHCP negotiations, the DHCP local server supplies an IP address
to the subscriber’s computer from a local address pool, as described in the
previous section.
The router maintains a host route that maps the IP address to the router’s
interface associated with the subscriber’s computer.
4.
The subscriber’s computer retains the IP address until the subscriber turns off
the computer.
Equal-Access Mode Overview
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Chapter 18: DHCP Local Server Overview