This page will describe how to setup IP-Helpers on Aruba, Dell, and Mellanox switches.
If you are migrating from a 1.3.2 system, the IP-helpers are being moved to the switches that are doing the Layer3 Routing. For most systems this will be moving the helper from the leaf to the spine.
IP-Helpers will reside on VLANs 1,2,4,7,2xxx, and 3xxx.
On both switches participating in VSX we will need to add configuration to the VLAN interfaces. The IP-Helper is used to forward DCHP traffic from one network to a specified IP address.
sw-24g03(config)# int vlan 1
sw-24g03(config-if-vlan)# ip helper-address 10.92.100.222
sw-24g03(config-if-vlan)# int vlan 2
sw-24g03(config-if-vlan)# ip helper-address 10.92.100.222
sw-24g03(config-if-vlan)# int vlan 4
sw-24g03(config-if-vlan)# ip helper-address 10.94.100.222
sw-24g03(config-if-vlan)# int vlan 7
sw-24g03(config-if-vlan)# ip helper-address 10.92.100.222
sw-24g04(config)# int vlan 1
sw-24g04(config-if-vlan)# ip helper-address 10.92.100.222
sw-24g04(config-if-vlan)# int vlan 2
sw-24g04(config-if-vlan)# ip helper-address 10.92.100.222
sw-24g04(config-if-vlan)# int vlan 4
sw-24g04(config-if-vlan)# ip helper-address 10.94.100.222
sw-24g04(config-if-vlan)# int vlan 7
sw-24g04(config-if-vlan)# ip helper-address 10.92.100.222
For CDU switches the IP helpers will look like the following.
Any 2xxx VLANs will have 10.92.100.222 as the ip helper-address and any 3xxx VLANs will have 10.94.100.222 as the ip helper-address
interface vlan 2000
ip helper-address 10.92.100.222
interface vlan 3000
ip helper-address 10.94.100.222
In Shasta v1.3.2 the IP-helpers for the NMN(VLAN2), and HMN(VLAN4) resided on the leafs, these are moving to the spines.
Remove IP-Helper configuration from the leafs.
sw-leaf-001(config)# interface vlan 2
sw-leaf-001(conf-if-vl-2)# no ip helper-address 10.92.100.222
sw-leaf-001(config)# interface vlan 4
sw-leaf-001(conf-if-vl-4)# no ip helper-address 10.94.100.222
On CDU switches the IP-Helpers need to be set accordingly. This is the same setting as 1.3. For 2xxx VLANS the config should look like the following.
sw-cdu-001# show running-configuration interface vlan 2000
!
interface vlan2000
mode L3
description CAB_1000_MTN_NMN
no shutdown
ip address 10.100.0.2/22
ip access-group nmn-hmn in
ip access-group nmn-hmn out
ip ospf 1 area 0.0.0.2
ip ospf passive
ip helper-address 10.92.100.222
For 3xxx VLANS the config should look like the following.
sw-cdu-001# show running-configuration interface vlan 3000
!
interface vlan3000
mode L3
description CAB_1000_MTN_HMN
no shutdown
ip address 10.104.0.2/22
ip access-group nmn-hmn in
ip access-group nmn-hmn out
ip ospf 1 area 0.0.0.4
ip ospf passive
ip helper-address 10.94.100.222
Configuration for Mellanox switch. Notice there is a helper for vlan 1,2,4, and 7.
## DHCP relay configuration
##
ip dhcp relay instance 2 vrf default
ip dhcp relay instance 4 vrf default
ip dhcp relay instance 2 address 10.92.100.222
ip dhcp relay instance 4 address 10.94.100.222
interface vlan 1 ip dhcp relay instance 2 downstream
interface vlan 2 ip dhcp relay instance 2 downstream
interface vlan 4 ip dhcp relay instance 4 downstream
interface vlan 7 ip dhcp relay instance 2 downstream
Verify the configuration.
sw-spine-002 [standalone: master] # show ip dhcp relay
Instance ID 2:
VRF Name: default
DHCP Servers:
10.92.100.222
DHCP relay agent options:
always-on : Disabled
Information Option: Disabled
UDP port : 67
Auto-helper : Disabled
-------------------------------------------
Interface Label Mode
-------------------------------------------
vlan1 N/A downstream
vlan2 N/A downstream
vlan7 N/A downstream
Instance ID 4:
VRF Name: default
DHCP Servers:
10.94.100.222
DHCP relay agent options:
always-on : Disabled
Information Option: Disabled
UDP port : 67
Auto-helper : Disabled
-------------------------------------------
Interface Label Mode
-------------------------------------------
vlan4 N/A downstream