Address - 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
Differentiating Between Clients with the Same Client ID or Hardware Address
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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.
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.
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 client.
The determination is based on whether the DHCP clients exist on the same or on different
subnets and subinterfaces.
Location of DHCP Clients with
Identical IDs or Addresses
On different subinterfaces in the
same subnet
On the same subinterface in different
subnets
On different subinterfaces in
different subnets
How DHCP Local Server Differentiates
Clients
By unique subinterface
By unique subnet
By unique subinterface and unique subnet
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