Configure a DHCP Relay Forwarding Path

Configure a forwarding path to specify the relay agent address and the DHCP server address to which to forward packets.

To use DHCP Relay for IPv6, you must configure at least one forwarding path and enable the relay on one interface.

Before you begin

For a VRF other than GlobalRouter, the interface must be first associated to that VRF.

About this task

The relay agent can use the IPv6 address of the interface or the VRRP global address linked to that interface. The relay forwards the DHCP messages only if VRRP is in the master state, otherwise the relay discards the messages.

You can configure only one relay agent on an interface. If you need to change the relay agent, you must delete all the forwarding paths with the old relay agent, and then configure the new relay agent.

For scaling information on DHCP Relay forwarding paths, see Fabric Engine Release Notes.

Procedure

Enter either Global Configuration mode or VRF Router Configuration mode for a specific VRF context:

enable

configure terminal

Optional: router vrf WORD<1-16>
Configure a forwarding path:

ipv6 dhcp-relay fwd-path WORD<0-255> WORD<0-255> [enable]

If you configure the forwarding path globally, the relay agent address can be any configured IP address of the relay interface or the VRRP global address linked to the relay interface.
To configure a forwarding path on an interface, enter Interface Configuration mode:

interface GigabitEthernet {slot/port[/sub-port] [-slot/port[/sub-port]] [,...]}

OR

interface vlan <1-4059>
Configure a forwarding path:

ipv6 dhcp-relay fwd-path WORD<0-255> [enable] [vrid WORD<1-255>]

If you configure the forwarding path on an interface, the relay agent address is either the smallest IP configured on the interface or the first VRRP global address configured, if the relay is the VRRP master. You do not specify the relay agent address as part of the command.
Note

IPv6 DHCP Relay is established only between agents within the context of each VRF.

Examples

Configure a forwarding path globally:

Switch:1(config)#ipv6 dhcp-relay fwd-path 1111::1111 1234::1234 enable

Configure a forwarding path on an interface:

Switch:1(config)#interface GigabitEthernet 1/1
Switch:1(config-if)#ipv6 dhcp-relay fwd-path 1234::1234 enable

Configure the VRRP master as the relay:

Switch:1(config-if)#ipv6 dhcp-relay fwd-path 1234::1234 vrid 12 enable

Variable Definitions

Use the data in the following table to use the ipv6 dhcp-relay fwd-path command.


Variable	Value
`<1-4059>`	Specifies the VLAN ID in the range of 1 to 4059. By default, VLAN IDs 1 to 4059 are configurable and the system reserves VLAN IDs 4060 to 4094 for internal use. On switches that support the vrf-scaling and spbm-config-mode boot configuration flags, if you enable these flags, the system also reserves VLAN IDs 3500 to 3998. VLAN ID 1 is the default VLAN and you cannot create or delete VLAN ID 1.
enable	Enables the forwarding path. The default is disabled.
{slot/port[/sub-port][-slot/port[/sub-port]][,...]}	Identifies the slot and port in one of the following formats: a single slot and port (slot/port), a range of slots and ports (slot/port-slot/port), or a series of slots and ports (slot/port,slot/port,slot/port). If the platform supports channelization and the port is channelized, you must also specify the sub-port in the format slot/port/sub-port.
vrid `WORD<1-255>`	Specifies the VRRP ID to use the VRRP master as the relay agent interface.
`WORD<0-255>`	Specifies the IPv6 address of the DHCP server for the interface configuration.
`WORD<0-255> WORD<0-255>`	Specifies the IPv6 address of the relay agent interface and the IPv6 address of the DHCP server for the global configuration.