DHCP relay not working on CISCO NCS540

[HassanJavaid42397]

Hi All,

Just need some help with my DHCP realy config on Cisco NCS540 running XR 7.1.1

Actually i was using Huawei switch before and below are the configs on Huawei for the DHCP.

interface Vlanif20

description 1st NNI - Voice Vlan

ip address 172.20.9.1 255.255.255.0

dhcp dscp-outbound 40

dhcp select relay

ip relay address 172.26.0.132

ip relay address 172.26.0.133

dhcp relay source-ip-address 172.20.9.1

#

I’m replicating the same config on the CISCO NCS540 as follows

dhcp ipv4

profile VOICE relay

  helper-address vrf default 172.20.9.1

!

interface Bundle-Ether1.20 relay profile VOICE

!

interface Bundle-Ether1.20

description 1st NNI - Voice vlan

service-policy output MARK_VOICE_QOS_P5_new

ipv4 helper-address vrf default 172.26.0.132

ipv4 helper-address vrf default 172.26.0.133

ipv4 address 172.20.9.1 255.255.255.0

encapsulation dot1q 20

!

But this doesn't seem to be working, really apprecite if someone could help me with this.

Thanks.

[Fredrik Lönnman]

I think you've got some configuration the wrong way, try it like this:

dhcp ipv4
profile VOICE relay
helper-address vrf default 172.26.0.132
helper-address vrf default 172.26.0.133
!
interface Bundle-Ether1.20 relay profile VOICE
!

interface Bundle-Ether1.20
description 1st NNI - Voice vlan
service-policy output MARK_VOICE_QOS_P5_new
ipv4 address 172.20.9.1 255.255.255.0
encapsulation dot1q 20

!

I believe the interface-level helper-address command is for other broadcast to unicast conversions except DHCP.

[HassanJavaid42397]

Hi Fredrik,

Thanks for the reply yes i changed the config but it's still stuck at DHCP offer stage the request is not going from client to server.

[miguelantonio.luna]

Hi, I'm currently opening a case for a similar issue...

After upgrade from 7.3.2 to 7.7.2, we started having the same issue. Relay request goes to server. But reply comes back, it is not forwarded on the LAN side.

7.6.2 and 7.8.1 fail also... 

I'am opening a case to see if there is a trick or if it's a bug.

The platform having the issue is N540X-6Z18G-SYS-A, on bigger modeks (non L) it looks to work.

Regards

Miguel

[tkarnani]

please see this bug

https://quickview.cloudapps.cisco.com/quickview/bug/CSCwd73742

[miguelantonio.luna]

Yeah, many thanks, this totally match our issue. I have updated the case with this info and requesting that engineer provide us the patch for 7.7.2 (it looks that we can only download the one for 7.6.2.

Thanks again
Miguel

[BrianDean]

Had this same issue. Found this thread linked to the bug...I was able to remove/reapply the dhcp relay config to get this operational again...though not sure for how long..

[diefierr]

@BrianDean  when was not working, you know if DHCP Server was getting the Discover? any debug you took? Is the DHCP Server a Linux Server or any other Cisco Router?

Diego