Configuring Dhcp Local Server To Support Creation Of Dynamic Subscriber Interfaces; Differentiating Between Clients With The Same Client Id Or Hardware Address - Juniper JUNOSE 11.1.X - BROADBAND ACCESS CONFIGURATION GUIDE 6-4-2010 Configuration Manual

JUNOSe 11.1.x Broadband Access Configuration Guide

Configuring DHCP Local Server to Support Creation of Dynamic Subscriber Interfaces

You can use the ip dhcp-local auto-configure agent-circuit-identifier command to
configure the DHCP local server to support the creation of dynamic subscriber
interfaces built over dynamic VLANs that are based on the agent-circuit-id option
(suboption 1) of the option 82 field in DHCP messages.
The use of the option 82 field enables you to stack an IP interface that is associated
with a particular subscriber over a dynamically created VLAN; the VLAN is dynamically
created based on the agent-circuit-id option (suboption 1) that is contained in the
DHCP option 82 field.
For information about configuring agent-circuit-id–based dynamic VLAN subinterfaces,
see the Configuring Dynamic Interfaces Using Bulk Configuration chapter in JUNOSe
Link Layer Configuration Guide.

Differentiating Between Clients with the Same Client ID or Hardware Address

A JUNOSe software feature enables the DHCP local server to create unique client IDs
to support roaming clients and to manage situations in which two clients in the
network have the same hardware address.
NOTE: This feature replaces the previous router behavior for DHCP local server client
roaming and duplicate address support. The ip dhcp-local unique-client-ids
command replaces the ip dhcp-local inhibit-roaming command, which has been
removed from the CLI and has no effect on the DHCP local server.
You can configure the method DHCP local server uses when the router receives a
DISCOVER or REQUEST packet that contains a client ID or hardware address that
matches the ID or address of a currently bound client on another subnet or
subinterface.
In the default configuration, the DHCP local server uses the DHCP client's subnet or
subinterface to differentiate duplicate clients and support client roaming. When a
new client, with a duplicate ID or hardware address, requests an address lease, DHCP
assigns that client a new address and lease the existing client's lease is unchanged.
The following table describes how the DHCP local server differentiates between a
new DHCP client with the same ID or hardware address as a currently bound DHCP
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Configuring DHCP Local Server to Support Creation of Dynamic Subscriber Interfaces
Use this command within a specific virtual router context.
This command requires that the user's DHCP control traffic and data traffic
traverse the same client-facing ingress port on the E Series router.