Cisco Cisco IOS Software Release 12.2(4)B

This feature module describes the DHCP Relay Support for MPLS VPN Suboptions feature in Cisco IOS 
Release 12.2(4)B and includes the following sections:

The DHCP relay agent information option (option 82) enables a Dynamic Host Configuration Protocol 
(DHCP) relay agent to include information about itself when forwarding client-originated DHCP 
packets to a DHCP server. The DHCP server can use this information to implement IP address or other 
parameter-assignment policies. The DHCP relay agent information option is organized as a single DHCP 
option that contains one or more suboptions that convey information known by the relay agent.

In some environments, a relay agent resides in a network element that also has access to one or more 
Multiprotocol Label Switching (MPLS) virtual private networks (VPNs). If a DHCP server wants to 
offer service to DHCP clients on those different VPNs, the DHCP server needs to know the VPN in 
which each client resides. The network element that contains the relay agent typically knows about the 
VPN association of the DHCP client and includes this information in the relay agent information option.

12.2(4)B

This feature was introduced.