Users Guide

NOTE: Link-selection gets functionally enabled only if Option-82 is enabled Globally and at the
interface level.
This command is restricted to the netadmin and sysadmin role users.
Example
OS10(conf)# ip dhcp-relay link-selection
Supported
Releases
10.5.2 or later
ip dhcp-relay source-interface
Configures the source interface to be used by the DHCP relay agent to decide the Gateway IP address used for forwarding a
DHCP packet received on the VRF.
Syntax
ip dhcp-relay {source-interface [ethernet node/slot/port | loopback
loopback-id | port-channel id-number | vlan vlan-id | virtual-network vn-
id]
Parameters
● ethernet node/ slot/port - Enter the ethernet interface type.
● loopback loopback-id - Enter the Loopback interface type.
● port-channel id-number - Enter the port channel interface type.
● vlan vlan-id - Enter the VLAN interface type.
● virtual-network vn-id - Enter the virtual network type.
Defaults No source-interface configuration on the VRF and the client connected interface IP address is used by
the relay for forwarding.
Command Mode IP VRF
Usage
Information
When you configure the DHCP-relay source interface for a given VRF, all the DHCP client-facing
interfaces associated with the VRF use this interface IP in the giaddr field to forward the packets to
and from the DHCP server.
The DHCP server uses the IP address of that source interface as destination for RELAY-REPLY packets.
We can configure a unique source-interface for the DHCP client facing interfaces (apart from the one
configured at the VRF level), by using the interface level source-interface command.
The source-interface IP address takes precedence for the giaddr field even if an interface IP address or
virtual anycast gateway IP address is present on the interface.
NOTE: You must enable the link-selection option globally to allocate the IP address on the client
subnet if the client-connected interface IP address and source interface IP address are in different
network domain.
This command is restricted to netadmin and sysadmin role users.
Example
OS10(conf-vrf)# ip dhcp-relay source-interface
ethernet Ethernet interface type
loopback Loopback interface type
port-channel Port-channel interface type
vlan Vlan interface type
virtual-network virtual network type
OS10(conf-vrf)# ip dhcp-relay source-interface loopback 1
Supported
Releases
10.5.2 or later
System management 319