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

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Table 99: Local Pool Selection in Standalone Mode Without AAA Authentication
How the DHCP Local Server Uses the Field Field
A giaddr, which indicates a client’s subnetwork, can be presented to the DHCP local server
in the client DHCP REQUEST message. The giaddr field in the DHCP request message usually
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. If it
finds a match, the router uses the matching 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. Received interface IP address
After the router selects a DHCP local pool, the DHCP local server first tries to
find a reserved IP address for the client in the selected pool. If no reserved
address is available, the router attempts to allocate a client’s requested IP address.
If the requested IP address is not available, the router allocates the next available
address in the pool. If a grace period is configured for the pool, the router assigns
the grace period to the allocated address. If no addresses are available in a pool,
the DHCP local server attempts to allocate an address from the linked pool, if
such a pool is configured.
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If AAA authentication is configured (as described in “Configuring AAA
Authentication for DHCP Local Server Standalone Mode” on page 487) and the
authentication is successful, the local server selects an IP address pool based on
the order presented in Table 100 on page 473. When the router finds a match, it
selects a pool based on the match and does not examine other parameters.
Table 100: Local Pool Selection in Standalone Mode with AAA Authentication
How the DHCP Local Server Uses the Field Field
The client’s RADIUS entry can be configured with a framed IP address, which the DHCP local
server can get from the AAA server when the client is authenticated.
If the AAA server specifies a framed IP address, the DHCP local server attempts to allocate
the address pool that contains the framed IP address and allocates that 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 RADIUS entry can also be configured
with a pool name, which the DHCP local server can get from the AAA server when the client
is authenticated. The AAA server must be configured to send RADIUS attributes to DHCP.
If AAA specifies an address pool name, the local server finds the pool with the matching
name and allocates an address from that pool.
Pool name
You can use a domain name as the name of a DHCP local pool. If RADIUS authenticates the
client using a domain name, the DHCP local server receives the domain name from the AAA
server.
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
Standalone Mode Overview
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Chapter 18: DHCP Local Server Overview