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Vyatta NOS documentation

Learn how to install, configure, and operate Vyatta Network Operating System (Vyatta NOS), which helps to drive our virtual networking and physical platforms portfolio.

service dhcp-relay relay-options

Specifies whether to add the Relay Agent Information option (option 82) to the client-to-server packet.

set service dhcp-relay relay-options [ hop-count count | max-size size | port port | relay-agents-packets policy ]
delete service dhcp-relay relay-options [ hop-count | max-size | port | relay-agents-packets ]
show service dhcp-relay relay-options [ hop-count | max-size | port | relay-agents-packets ]
hop-count count
Optional. Sets the hop count for outgoing relayed messages. After the hop count is reached, the packet is discarded. The hop count should be set high enough that relayed packets are able to reach the DHCP server. The count ranges from 0 through 255. The default count is 10.
max-size size
Optional. Sets the maximum size of the DHCP packet to be created after appending the relay agent information option. If, after appending the information, the packet exceeds this size, the packet is forwarded without appending the information. This size should be set to the lowest MTU size in your network. The size ranges from 64 through1400. The default size is 576.

If this option is not configured, the router does not forward DHCP packets that exceed the MTU of the interface on which relaying is configured.

port port
Optional. Specifies the port on this interface that relays DHCP client messages. This should be done only for debugging because the behavior changes; responses are broadcast rather than being sent to port 68 of the requesting client. The port ranges from 1 through 65535.
relay-agents-packet policy
Optional. Sets the reforwarding policy for a DHCP relay agent. The router takes this action if the DHCP message already contains relay information. The policy is one of the following:

append: The DHCP relay agent may append its own set of relay options to the packet, leaving the supplied option field intact.

discard: If the packet already contains relay information, it is discarded.

forward: The packet is forwarded regardless of whether it contains relay information.

replace: The DHCP relay agent may replace the supplied option field with its own set of relay options.

The default policy is forward.

Configuration mode


service {
	dhcp-relay {
		relay-options {
			hop-count count 
			max-size size 
			port port 
			relay-agents-packets policy
		}
	}
}

Use this command to configure the Relay Agent Information option (option 82) in the client-to-server packet, as specified by RFC 3046, and configure DHCP relay options.

Setting the port to a value other than 67 should be done only for debugging. When this is done, DHCP requests from clients are still accepted on port 67, but the responses from DHCP servers are forwarded to broadcast address 255.255.255.255 port 0 rather than on port 68, where DHCP clients listen.

Use the set form of this command to set DHCP relay options.

Use the delete form of this command to restore default DHCP relay options.

Use the show form of this command to view DHCP relay option configuration.