Cisco Catalyst 4500 Series Software Configuration Guide

61-2
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.8.0E and IOS 15.2(4)E
Chapter 61 DHCPv6 Options Support
Information About DHCPv6 Options Support
Information About DHCPv6 Options Support
• DHCPv6 Relay Agent Overview, page 61-2
• DHCPv6 Relay Options: Remote-ID, page 61-2
• DHCPv6 Interface-ID, page 61-3
• Lightweight DHCPv6 Relay Agent, page 61-3
• Interoperability between DHCPv6 Relay Agents and LDRA, page 61-3
• LDRA for VLANs and Interfaces, page 61-4
• CAPWAP Access Controller DHCPv6 Option, page 61-4
DHCPv6 Relay Agent Overview
A DHCPv6 relay agent is any host that forwards DHCP packets between clients and servers. Relay
agents are used to forward requests and replies between clients and servers when they are not on the same
physical subnet.
A DHCPv6 relay agent, which may reside on the client’s link, is used to relay messages between the
client and the server. The DHCPv6 relay agent operation is transparent to the client. A DHCPv6 client
locates a DHCPv6 server using a reserved, link-scoped multicast address. For direct communication
between the DHCPv6 client and the DHCPv6 server, both of them must be attached to the same link.
However, in some situations where ease of management, economy, or scalability is a concern, it is
desirable to allow a DHCPv6 client to send a message to a DHCPv6 server that is not connected to the
same link.
DHCPv6 Relay Options: Remote-ID
The DHCPv6 Remote ID Option feature adds the remote identification (remote-ID) option to relayed
(RELAY-FORWARD) DHCPv6 packets.
The remote-ID option provides information to the DHCPv6 server, which includes port information, the
system’s DHCP Unique Identifier (DUID), and the virtual LAN (VLAN) ID. This information can be
used to uniquely identify both the relay and the port on the relay through which the client packet arrived.
The DHCPv6 server uses this information to select parameters specific to a particular user, host, or
subscriber modem.
The addition of the remote-ID option to the RELAY-FORWARD packet occurs automatically and no user
configuration is necessary.
The DHCPv6 server does not need to echo the remote-ID option in the RELAY-REPLY packet. The
Internet Assigned Numbers Authority (IANA) has assigned the DHCPv6 option code 37 for the relay
agent remote-ID option.
If the remote-ID option is included in the RELAY-REPLY packet, the option is removed from the packet
before it is relayed to the client.

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E