Understanding Dhcp Option-82 - Cisco ASR 9000 Series Configuration Manual

Establishing Subscriber Sessions
Command or Action
Step 4
limit lease per-interface value
Example:
RP/0/RSP0/CPU0:router(config-dhcpv4-proxy-profile)#
limit lease per-interface 2400
Step 5 Use the commit or end command.
Specifying the Lease Limit for an Interface: An example
configure
dhcp ipv4
profile profile1 proxy
limit lease per-interface 2400
!
!
end

Understanding DHCP Option-82

DHCP Option 82 allows the DHCP server to generate IP addresses based on the location of the client device.
This option defines these sub-options:
• Agent Circuit ID Sub-option—This sub-option is inserted by DSLAM and identifies the subscriber line
• Agent Remote ID Sub-option—This sub-option is inserted by DSLAM or BNG in an l2-connected
• VPN identifier sub-option—This sub-option is used by the relay agent to communicate the VPN for
• Subnet Selection Sub-option—This sub-option allows the separation of the subnet from the IP address
OL-26148-02
in the DSLAM.
topology. It is the client MAC address, but can be overridden. With the DHCP proxy or relay, the client
MAC address is lost by the time the packet gets to the DHCP server. This is a mechanism that preserves
the client MAC when the packet gets to the server.
every DHCP request that is sent to the DHCP server, and it is also used to forward any DHCP reply that
the DHCP server sends back to the relay agent.
and is used to communicate with the relay agent. In a DHCP processing, the gateway address specifies
both the subnet on which a DHCP client resides, and the IP address that the server uses to communicate
with the relay agent.
Cisco ASR 9000 Series Aggregation Services Router Broadband Network Gateway Configuration Guide, Release
Understanding DHCP Option-82
Purpose
Specifies the lease limit for each interface.
commit—Saves the configuration changes and remains
within the configuration session.
end—Prompts user to take one of these actions:
• Yes— Saves configuration changes and exits the
configuration session.
• No—Exits the configuration session without
committing the configuration changes.
• Cancel—Remains in the configuration mode,
without committing the configuration changes.
4.2.x
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