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NEXUS 93180 DHCP relay issues

mseanmiller
Level 1
Level 1

We have a pair of NEXUS 93180LC-EX switches in a NX-OS setup.

They act as the core and have multiple VLAN's with HSRP enabled.

We had a single DHCP relay agent enabled and that was working fine.

 

The problem we are seeing is when we tried to upgrade and added 2 additional DHCP relay agents and downed the original relay (Without removing the relay from the NEXUS) DHCP doesn't seem to work.

 

When I remove the dead agent from the NEXUS then DHCP does work and all is good.

 

In IOS you can have a dead helper address as long as you have other helpers.

 

So does anyone have anything they can share on DHCP helper process with NEXUS.

 

We are running ver 7.0(3)I7(2). The 3 helpers are on 2 different subnets none of which are the the server VLANs.

2 Replies 2

shaikmohib
Level 1
Level 1

Hey Sean, 

We have seen something similar in our environment our cat devices support the multiple helper address. But can you share the following output.


show ip dhcp relay
show running-config dhcp

Here ya go,

 

It's pretty straight forward.

 

Prior to this we had a single DHCP server helper on a different VLAN and all was good.

 

When we added the addition of an HA pair of helpers and we shutdown and migrated DHCP services to the HA DHCP pair is when we started having issues. (The original server was still on(Pinging) but DHCP services were turned off.)

 

Now for the most part things are working however RHEL (RedHat) VM's are still not happy. Windows VM's in a different VLAN are happy.

 

!Command: show running-config dhcp
!Time: Thu Jun 30 07:47:22 2022

version 7.0(3)I7(2)
feature dhcp

service dhcp
ip dhcp relay
ipv6 dhcp relay


interface Vlan3
ip dhcp relay address 172.16.219.82
ip dhcp relay address 172.16.219.81

interface Vlan99
ip dhcp relay address 172.16.219.81
ip dhcp relay address 172.16.219.82

interface Vlan140 (This is the VLAN we are having issues with)
ip dhcp relay address 172.16.219.82
ip dhcp relay address 172.16.219.81

interface Vlan163
ip dhcp relay address 172.16.219.81
ip dhcp relay address 172.16.219.82

interface Vlan179
ip dhcp relay address 172.16.219.81
ip dhcp relay address 172.16.219.82

 

and

DF-R2C1-C93180L-DSwc-C2# show ip dhcp relay
DHCP relay service is enabled
Insertion of option 82 is disabled
Insertion of option 82 customize circuitid is disabled
Insertion of VPN suboptions is disabled
Insertion of cisco suboptions is disabled
Global smart-relay is disabled
Relay Trusted functionality is disabled
Relay Trusted Port is Globally disabled
V4 Relay Source Address HSRP is Globally disabled

Smart-relay is enabled on the following interfaces:
------------------------------------------------------


Subnet-broadcast is enabled on the following interfaces:
------------------------------------------------------


Relay Trusted Port is enabled on the following interfaces:
----------------------------------------------------------


Relay Source Address HSRP is enabled on the following interfaces:
-------------------------------------------------------------------

Helper addresses are configured on the following interfaces:
Interface Relay Address VRF Name
------------- ------------- --------
Vlan3 172.16.219.81
Vlan3 172.16.219.82
Vlan99 172.16.219.81
Vlan99 172.16.219.82
Vlan140 172.16.219.82
Vlan140 172.16.219.81
Vlan163 172.16.219.81
Vlan163 172.16.219.82
Vlan179 172.16.219.81
Vlan179 172.16.219.82

 

 

 

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