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NVIDIA MLNX-GW User Manual for NVIDIA Skyway Appliance v8.2.2200

DHCP Relay

Since Dynamic Host Configuration Protocol must work correctly even before DHCP clients have been configured, the DHCP server and DHCP client need to be connected to the same network.

In larger networks, this is not always practical because each network link contains one or more DHCP relay (DHCP-R) agents. These agents receive messages from DHCP clients and forward them to DHCP servers thus extending the reach of the DHCP beyond the local network.

DHCP-R is supported for IPv4 and IPv6.

DHCP-R is supported for both primary IP subnet and secondary IP subnets.

DHCP-R Virtual Routing and Forwarding (VRF) Auto-Helper

In some cases it is desired that DHCP-R functionality is automatically enabled to all IP interfaces in the system. For this purpose a vrf-auto-helper may be configured on a DHCP-R instance which would provide DHCP-R services automatically for each newly created interface on a VRF.

Only one instance in each VRF can have vrf-auto-helper capability. Whenever a new instance is created in a VRF, it automatically becomes a vrf-auto-helper.

It is possible to manually disable auto-helper capability for the instance. See the command “vrf-auto-helper” for more information.

Upstream and Downstream Interfaces

It is possible to define an interface to be downstream, upstream, or bidirectional (both downstream and upstream):

Bidirectional interface – capable of performing downstream and upstream functionalities
Downstream interface (default configuration) – the interface on which queries are received from clients or from other relay agents
Upstream interface – the interface to which queries from clients and other relay agents are forwarded

DHCP Relay Commands

ip dhcp relay

	ip dhcp relay [instance <instance-id>] no ip dhcp relay [instance <instance-id>] Enters DHCP relay instance configuration mode, and creates DHCP instance in active VRF context. The no form of the command deletes the instance and DHCP relay process corresponding to it.
Syntax Description	instance-id	Range: 1-8
Default	N/A
Configuration Mode	config
History	3.6.3004
Example	switch (config)# ip dhcp relay instance 1 switch (config ip dhcp relay instance 1)#
Related Commands
Notes	If an instance is not specified then instance 1 is used (if nonexistent, then it is created).

address

	address <ip-address> no address <ip-address> Configures the DHCP server IP address on a particular instance. The no form of the command deletes the DHCP server IP address.
Syntax Description	ip-address	Valid IP unicast address of DHCP server.
Default	N/A
Configuration Mode	config ip dhcp relay
History	3.3.4150
	3.6.1002	Added VRF parameter
	3.6.3004	Enhanced command for DHCP-R multi-instance
Example	switch (config ip dhcp relay instance 1)# address 1.2.3.4
Related Commands	ip dhcp relay
Notes	Up to 16 IP addresses may be configured To enable DHCP relay instance, at least one IP address should be configured, or always-on parameter should be turned on using the command “ip dhcp relay always-on” The following option for running this command is also possible: ip dhcp relay instance 1 address <ip-address>. However, if an instance is not specified then instance 1 is used (if nonexistent, then it is created).

always-on

	always-on no always-on Enables broadcast mode on a particular instance. The no form of the command disables the broadcast mode from instance.
Syntax Description	vrf	VRF name
Default	Disabled
Configuration Mode	config ip dhcp relay
History	3.3.4150
	3.6.1002	Added VRF parameter
	3.6.3004	Enhanced command for DHCP-R multi-instance
Example	switch (config ip dhcp relay instance 1)# always-on
Related Commands	ip dhcp relay
Notes	Broadcasts DHCP requests to all interfaces with the DHCP relay agent for given VRF In order to enable DHCP relay, at least one IP address should be configured, or always-on parameter should be turned on using this command When DHCP servers are configured, requests are forwarded only to configured servers The following option for running this command is also possible: ip dhcp relay instance 1 always-on. However, if an instance is not specified then instance 1 is used (if nonexistent, then it is created).

information option

	information option no information option Enables DHCP relay agents to insert option 82 on the packets of a particular instance. The no form of the command removes option 82 from the packets.
Syntax Description	N/A
Default	Disabled
Configuration Mode	config ip dhcp relay
History	3.3.4150
History	3.6.3004	Enhanced command for DHCP-R multi-instance
Example	switch (config ip dhcp relay instance 1)# information option
Related Commands	ip dhcp relay
Notes	The following option for running this command is also possible: ip dhcp relay instance 1 information option. However, if an instance is not specified then instance 1 is used (if nonexistent, then it is created).

vrf

	vrf <vrf-name> no vrf <vrf-name> Configures mention instance in the given VRF. The no form of the command moves the instance back to default VRF.
Syntax Description	N/A
Default	N/A
Configuration Mode	config ip dhcp relay
History	3.6.3004
Example	switch (config ip dhcp relay instance 1)# vrf 2
Related Commands
Notes	If no VRF is specified, then the DHCP-R instance is created in the active VRF If the VRF is changed, then the configuration of the DHCP-R instance is automatically deleted The following option for running this command is also possible: ip dhcp relay instance 1 vrf <vrf-name>. However, if an instance is not specified then instance 1 is used (if nonexistent, then it is created).

port

	port <udp-port> no port <udp-port> Changes the UDP port for the given instance. The no form of the command sets the UDP port to default value.
Syntax Description	udp-port	UDP port Range: 1-65534
Default	67
Configuration Mode	config ip dhcp relay
History	3.6.3004
Example	switch (config ip dhcp relay instance 1)# port 65534
Related Commands
Notes	The system allocated 2 ports: One is the server port (udp-port), and another is client port (udp-port+1) The following option for running this command is also possible: ip dhcp relay instance 1 port <udp-port>. However, if an instance is not specified then instance 1 is used (if nonexistent, then it is created).

use-secondary-ip

	use-secondary-ip no use-secondary-ip Enables the switch to relay a single request from the client multiple times simultaneously, with each of the IP addresses configured on the corresponding downstream interfaces as the respective gateway address (linkaddr field of IPv4 DHCP request packet). The no form of the command disables this function.
Syntax Description	N/A
Default	Disabled
Configuration Mode	config ip dhcp relay
History	3.6.8008
Example	switch (config ip dhcp relay instance 1)# use-secondary-ip
Related Commands
Notes

vrf-auto-helper

	vrf-auto-helper no vrf-auto-helper Makes all L3 interfaces (existing/newly created) to be part of the given instance. The no form of the command resets this parameter to its default
Syntax Description	N/A
Default	N/A
Configuration Mode	config ip dhcp relay
History	3.6.3004
Example	switch (config ip dhcp relay instance 1)# vrf-auto-helper
Related Commands
Notes	Every new DHCP-R instance created in a VRF automatically becomes the VRF auto-helper if no other DHCP-R instance has been configured VRF auto-helper previously in that VRF The following option for running this command is also possible: ip dhcp relay instance 1 vrf-auto-helper. However, if an instance is not specified then instance 1 is used (if nonexistent, then it is created).

ip dhcp relay instance (config interface)

	ip dhcp relay instance <instance-id> [downstream] [upstream] no ip dhcp relay instance <instance-id> [downstream] [upstream] Enables the given interface to listen for DHCP packets coming from specified instance (i.e. binds interface to that instance). The no form of the command removes the interface mapping from that instance.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
	downstream	The interface on which queries are received from clients or from other relay agents
	upstream	The interface to which queries from clients and other relay agents should be forwarded
Default	Downstream
Configuration Mode	config interface ethernet set as router port interface config interface port-channel config interface vlan
History	3.6.3004
History	3.6.6000	Added downstream and upstream parameters
Example	switch (config interface ethernet 1/13)# ip dhcp relay instance 7 downstream
Related Commands
Notes	In order to enable DHCP relay, other than configuring the downstream interface, at least one IP address must be configured, or the always-on parameter must be activated using the command “ip dhcp relay always-on” When DHCP servers are configured, requests are forwarded only to configured servers At most, 64 interfaces can be configured on each instance Only an existent DHCP-R may be specified Each interface is either upstream, downstream, or bidirectional If only downstream interfaces are defined, all interfaces in VRF are assumed to be upstream interfaces

clear ip dhcp relay counters

	clear ip dhcp relay counters [vrf {<vrf-name> \| all} \| instance <instance-id>] Clears all DHCP relay counters (all interfaces) in a given VRF or instance.
Syntax Description	vrf-name	VRF name or “all” for all VRFs
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Default	N/A
Configuration Mode	config
History	3.3.4150
	3.6.1002	Added VRF parameter
	3.6.3004	Enhanced command for DHCP-R multi-instance
	3.6.5000	Added “all” parameter
Example	switch (config)# clear ip dhcp relay counters
Related Commands
Notes	If no DHCP-R instance is specified, then the counters of all DHCP-R instances are cleared If a VRF is specified, then the counters of all instances on that VRF are cleared The command “clear counters all” may also be used to clear all DHCP-R counters

ip dhcp relay information option circuit-id

	ip dhcp relay information option circuit-id <label> no ip dhcp relay information option circuit-id Specifies the content of the circuit ID sub-option attached to the client DHCP packet when it is forwarded a DHCP server. The no form of the command removes the label assigned.
Syntax Description	label	Specifies the label attached to packets. The string may be up to 15 characters.
Default	The label is taken from the IP interface name (e.g. “vlan1”)
Configuration Mode	config interface vlan config interface ethernet set as router port interface config interface port-channel set as router port interface
History	3.3.4150
History	3.6.1002	Added VRF parameter
Example	switch (config interface vlan 10)# ip dhcp relay information options circuit-id my-label
Related Commands
Notes	The circuit ID sub-option is an IP interface attribute which is shared across all DHCP-R instances.

ipv6 dhcp relay instance

	ipv6 dhcp relay instance <instance-id> [vrf-auto-helper] [downstream] [upstream] no ipv6 dhcp relay instance <instance-id> [vrf-auto-helper] Enables DHCP relay instance configuration mode, and creates DHCP instance in active VRF context. The no form of the command deletes the DHCP relay instance.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
	vrf-auto-helper	Instance becomes VTF auto helper
	downstream	The interface on which queries are received from clients or from other relay agents
	upstream	The interface to which queries from clients and other relay agents should be forwarded
Default	Disabled
Configuration Mode	config interface ethernet config interface port-channel config interface vlan
History	3.6.4070
History	3.6.6000	Added downstream and upstream parameters
Example	switch (config interface ethernet 1/1) # ipv6 dhcp relay instance 1 downstream
Related Commands
Notes	An instance without an assigned addresses is sent to All_DHCP_servers address Each interface is either upstream, downstream, or bidirectional At most, 64 interfaces can be configured on each instance If only downstream interfaces are defined, all interfaces in VRF are assumed to be upstream interfaces An instance must meet two conditions to become active: A server address or an upstream interface A downstream interface

ipv6 dhcp relay instance (global server)

	ipv6 dhcp relay instance <instance-id> address <ipv6-address or list of addresses> no ipv6 dhcp relay instance <instance-id> address <ipv6-address or list of addresses> Configure the server address on a particular instance. The no form of the command will delete the server address from instance.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Syntax Description	ipv6-address	Valid global unicast IPv6 server address Up to 16 addresses can be assigned per instance
Default	N/A
Configuration Mode	config
History	3.6.4070
Example	switch (config)# ipv6 dhcp relay instance 1 address 2001::1
Related Commands
Notes	An instance without an assigned addresses will send to All_DHCP_servers address

ipv6 dhcp relay instance address (destination address on interface)

	ipv6 dhcp relay instance <instance-id> address <link-local-address> no ipv6 dhcp relay instance <instance-id> address <link-local-address> Configures the destination address on a particular instance on a specific upstream interface. Only link local address is supported. The no form of the command deletes the destination address on a specific upstream interface from a particular instance.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Syntax Description	ipv6-address	Destination unicast or multicast address Only link local address in supported
Default	N/A
Configuration Mode	config interface ethernet config interface port-channel config interface vlan
History	3.6.4070
Example	switch (config interface ethernet 1/13)# ipv6 dhcp relay instance 1 address fe80::1
Related Commands
Notes	Up to 16 addresses can be assigned per instance

ipv6 dhcp relay instance interface-id option

	ipv6 dhcp relay instance <instance-id> interface-id option no ipv6 dhcp relay instance <instance-id> interface-id option Enables the instance to insert interface ID option. The no form of the command disables this option.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Default	Default interface-id is an interface name (e.g. vlan1, eth1/1)
Configuration Mode	config
History	3.6.4070
Example	switch (config)# ipv6 dhcp relay instance 1 interface-id option
Related Commands
Notes

ipv6 dhcp relay instance vrf

	ipv6 dhcp relay instance <instance-id> vrf <vrf-name> no ipv6 dhcp relay instance <instance-id> vrf <vrf-name> Configures instance in the given VRF. The no form of the command will reset the instance back to default VRF.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Syntax Description	vrf-name	Name of VRF
Default	Default VRF
Configuration Mode	config
History	3.6.4070
Example	switch (config)# ipv6 dhcp relay 1 vrf test
Related Commands
Notes	When an instance is moved from one VRF to another - it loses all its current configuration.

ipv6 dhcp relay instance port

	ipv6 dhcp relay instance <instance-id> port <udp-port> no ipv6 dhcp relay instance <instance-id> port <udp-port> Modifies the UDP port for the given instance. The no form of the command will set the UDP port to default value.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Syntax Description	port	UDP Port ID Range: 1-65534
Default	UDP port 547
Configuration Mode	config
History	3.6.4070
Example	switch (config)# ipv6 dhcp relay 1 port 555
Related Commands
Notes

ipv6 dhcp relay instance interface-id option

	ipv6 dhcp relay instance <instance-id> interface-id option [user-defined-id] Specifies the content of the interface-id option that will be sent by the relay agent.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Syntax Description	user-defined-id	Interface ID option content Length: 1-15 (char) Default: interface name
Default	N/A
Configuration Mode	config
History	3.6.4070
Example	switch (config)# ipv6 dhcp relay instance <instance-id> interface-id option eth1/1
Related Commands
Notes

ipv6 dhcp relay instance use-secondary-ip

	ipv6 dhcp relay instance use-secondary-ip no ipv6 dhcp relay instance use-secondary-ip Enables the switch to relay a single request from the client multiple times simultaneously, with each of the IP addresses configured on the corresponding downstream interfaces as the respective gateway address (giaddr field of IPv6 DHCP request packet). The no form of the command disables this function.
Syntax Description	N/A
Default	Disabled
Configuration Mode	config
History	3.6.8008
Example	switch (config ipv6 dhcp relay instance 1)# use-secondary-ip
Related Commands
Notes

clear ipv6 dhcp relay counters

	clear ipv6 dhcp relay counters [vrf {<vrf-name> \| all} \| instance <instance-id>] Clears DHCP relay counters for specific instance or all instances in given VRF or all instances in the system.
Syntax Description	vrf-name	VRF name or “all” for all VRFs
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Default	N/A
Configuration Mode	config
History	3.6.4070
History	3.6.5000	Added “all” parameter
Example	switch (config)# clear ipv6 dhcp relay counters vrf all
Related Commands
Notes

show ip dhcp relay

	show ip dhcp relay [instance <instance-id>] Displays general DHCP configuration.
Syntax Description	instance-id	If instance ID is specified, then a particular instance configuration is displayed
Default	N/A
Configuration Mode	Any command mode
History	3.3.4150
	3.6.1002	Added VRF and all parameters
	3.6.3004	Updated example and parameters
	3.6.6000	Updated example
	3.6.8008	Updated example
Example	switch (config)# show ip dhcp relay Instance ID 1: VRF Name: default DHCP Servers: 1.1.1.1 DHCP relay agent options: always-on : Disabled Information Option: Disabled UDP port : 67 Auto-helper : Disabled ------------------------------------------- Interface Label Mode ------------------------------------------- eth1/5 N/A downstream
Related Commands
Notes	If no DHCP-R instance is given, then all DHCP-R instances are displayed Only configured interfaces are displayed Once vrf-auto-helper is enabled, no interface is displayed

show ip dhcp relay counters

	show ip dhcp relay counters [instance <instance-id> \| vrf <vrf-name>] Displays the DHCP relay counters.
Syntax Description	instance-id	Displays the DHCP relay counters for a given instance
Syntax Description	vrf	Displays the DHCP relay counters in a given VRF
Default	N/A
Configuration Mode	Any command mode
History	3.3.4150
	3.6.1002	Added VRF and all parameters
	3.6.5000	Updated example
	3.6.8008	Updated example
Example
switch (config) # show ip dhcp relay counters Instance 1: VRF Name: vrf-default DHCP Counter flags: SPR : Server Packets Received SPE : Server Packets Error SPRE: Server Packet Relayed CPR : Client Packets Received RP : Relay Packets RE : Relay Errors ----------------------------------- Req/Resp Received Forwarded ----------------------------------- All Req 0 0 All Res 0 0 ------------------------------------------------------ If SPRE SPE SPR CPR ------------------------------------------------------ eth1/5 0 0 0 0 Packets Relayed to Server: ------------------------------------ Server RP RE ------------------------------------ 1.1.1.1 0 0
Related Commands
Notes

show ipv6 dhcp relay

	show ipv6 dhcp relay [instance <instance-id>] Displays general DHCP configuration on all instances. If instance ID is defined then specific instance configuration is displayed.
Syntax Description	instance-id	DHCP instance ID Range: 1-8
Default	N/A
Configuration Mode	Any command mode
History	3.6.4070	First release
	3.6.5000	Updated example
	3.6.6000	Updated example
	3.6.8008	Updated example
Example	switch (config)# show ipv6 dhcp relay Instance ID 1: VRF Name: default DHCP Servers: 2001:db8:701f::8f9 DHCP relay agent options: All_DHCP_Servers : Disabled Interface-id Option: Disabled UDP port : 547 Auto-helper : Disabled Status : Down ------------------------------------------- Interface Label Mode ------------------------------------------- eth1/5 N/A downstream
Related Commands
Notes	If no DHCP-R instance is given, then all DHCP-R instances are displayed Only configured interfaces are displayed Once vrf-auto-helper is enabled, no interface is displayed

show ipv6 dhcp relay counters

	show ipv6 dhcp relay counters [instance <instance-id> \| vrf <vrf-name>] Displays the DHCPv6 relay counters.
Syntax Description	instance-id	Displays the DHCPv6 relay counters for a given instance
Syntax Description	vrf	Displays the DHCPv6 relay counters in a given VRF
Default	N/A
Configuration Mode	Any command mode
History	3.3.4150
History	3.6.8008	Updated example
Example
switch (config) # show ipv6 dhcp relay counters Instance 1: VRF Name: vrf-default DHCP Counter flags: SPR : Server Packets Received SPE : Server Packets Error SPRE: Server Packet Relayed CPR : Client Packets Received RP : Relay Packets RE : Relay Errors ----------------------------------- Req/Resp Received Forwarded ----------------------------------- All Req 0 0 All Res 0 0 ------------------------------------------------------ If SPRE SPE SPR CPR ------------------------------------------------------ eth1/5 0 0 0 0 Packets Relayed to Server: ------------------------------------------------------------------- Server RP RE ------------------------------------------------------------------- 2001:db8:701f::8f9 0 0
Related Commands
Notes

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