DHCP issue under VRF & VRF Forwarding

[mailminhaz]

I have 2 Cisco 9606 switches as the core with SVL.

I just want to share that, as per our network design, we have VRF, VRF Forwarding VLANs, DHCP, etc. configurations. However, I have been observing some issues related to DHCP.

In the access VLAN, DHCP is not broadcasting IP addresses, so VLAN access ports are not getting IP addresses automatically, though manual IP assignment is working and VLAN SVI is being assigned.

I have done basic troubleshooting from my side, with out vrf forwarding access port getting IP Through DHCP but with vrf forwarding DHCP IP not working.

I am wondering if I am missing any configuration related to VRF, VLAN Forwarding VRF, or DHCP configuration for the access network, i suspect if there is any additional command is required due to ios?

Device: Cisco Catalyst 9606
IOS: Cisco IOS XE Software, Version 17.09.05

[balaji.bandi]

Make sure the DHCP aware of VRF config also Global config you need this config :

ip dhcp relay information option vpn

VRF aware helper example :

interface Vlan10
ip vrf forwarding VRF10
ip address 192.168.100.1 255.255.255.0
ip helper-address 192.168.200.254

check some explanation is that works :

https://blog.ipspace.net/2023/03/netlab-vrf-dhcp-relay/

Note : make sure DHCP Server reachable using VRF (if they are not in the same switch).

[mailminhaz]

Ok, I have narrowed down the problem.

- If the interface vlan is configured with vrf forwarding then DHCP is not working.
- If I remove the configuration interface vlan vrf forwarding, still DHCP is not working.

- But, if I configured the IP DHCP Pool from the beginning (without interface vlan vrf forwarding), in this case, DHCP is working.

[MHM Cisco World]

Friend you need vlan svi to get IP or cleint in vlan get IP ftom dhcp server?

Can you more elaborate 

MHM

[balaji.bandi]

Where is the DHCP Server ?

You need to show the configuration for us to understand the issue.

VLAN and VRF 2 different, VLAN seperation of Layer 2 domain, VRF Seperate instance of routing table.

- But, if I configured the IP DHCP Pool from the beginning (without interface vlan vrf forwarding), in this case, DHCP is working.  - not sure what is begining ?