Hey all,
We have a subinterface configured with an IP Helper address of a remote DHCP Server, this subinterface is also in a VRF. To add further complexity this VRF has a locally configured DHCP pool which is used for other VLAN in the same VRF.
We want to have any hosts on VLAN 123 to use the IP Helper DHCP server and not get a IP from the locally configured pool, When we test this the hosts always get assigned an IP from the local pool and the IP Helper seems to be ignored. We have tried configuring ip helper xxx.xxx.xxx as well as ip helper xxx.xxx.xxx.xxx global within the VLAN but no joy.
If we remove the VRF from the VLAN they get an address from the correct DHCP Server, however this VLAN needs to be within this VRF.
See below an example of the config as it sits today.
interface GigabitEthernet0/0/1.311
description xxxxxxxxxxx
encapsulation dot1Q 311
vrf forwarding internet
ip address 10.xxx.xx.3 255.255.252.0
ip helper-address 10.xxx.xxx.20
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat inside
!
Config with the ip helper global set.
interface GigabitEthernet0/0/1.311
description xxxxxxxxxxx
encapsulation dot1Q 311
vrf forwarding internet
ip address 10.xxx.xx.3 255.255.252.0
ip helper-address 10.xxx.xxx.20 global
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat inside
Other part of the config that may help.
ip dhcp pool hotspot-dhcp
vrf internet
network 172.20.20.0 255.255.255.0
dns-server 172.20.20.12 172.20.20.212
default-router 172.20.20.1
Anyone got any ideas.
This is on a ISR4431 running Version 15.5(3)S4b
