DHCP Will Not Work after Switch Swap

[koverpeck]

I have a WS-C3650-48PD that was needing to swapped out due to some ports not working. However when I swap it out with an identical switch (granted its on an older software) DHCP does not work for any of my clients connecting to the switch.

The only major changes would be that instead of EIGRP we used static routing instead because the replacement switch does not have the right licensing. When we swap the switches SSH works fine. I can access the switch remotely and all of the vlans can ping the dhcp server. Helper addresses are in place. However none of the vlans have DHCP working.

[marce1000]

 - Ref : https://bst.cisco.com/bugsearch/bug/CSCux39091 , I would strongly advice to sync it with the same software version similar to  the one who got replaced.

 M.

[koverpeck]

Switch being taken out - 16.6.5

Replacement switch - 16.3.11 (It was upgraded from 16.3.3 in the troubleshooting process)

[Reza Sharifi]

Appears to be a routing issue if all worked with EIGRP and not with static routes. Make sure all static routes are in place and you can trace from a client to the DHCP server and from the server back to a client or SVI address on the switch.

HTH

[koverpeck]

Client is assigned a static IP address and network connectivity works. Plus, routing connectivity from all subnets to the DHCP server work and network connectivity from the DHCP server to the switch and its networks. Traceroutes also follow the same path both directions.

[Reza Sharifi]

Ok, good to know. Can you double-check to make sure "IP routing" is enabled on the switch? Also, does the switch have the correct default route installed? Does the DHCP server have the correct gateways? Maybe resetting DHCP services on the server can restart things.

HTH

[koverpeck]

Can you double-check to make sure "IP routing" is enabled on the switch?

Enabled

Also, does the switch have the correct default route installed?

Default route is the ip address on the router the switch is connected to that takes it over the DMVPN tunnel.

Does the DHCP server have the correct gateways?

The vlans were configured with the identical IP addresses as the previous switch so the router field in the DHCP server options should be fine.

Maybe resetting DHCP services on the server can restart things.

This can't be as numerous other networks use this DHCP server. What we have done server side is remove a host from the dhcp leased IPs pool and see if that host reconnects directly plugged into the swtich. No Success. We also ran wireshark on the window DHCP server and we see no DHCP traffic from the subnets configured on this switch.

[NetworkDave]

@koverpeck,

Please provide the network topology.

Switch model, feature set, and IOS version aside...how was the replacement switch configured, from the previous switch config file or manually?

You mentioned that a client in an affected VLAN (on the replaced switch) was given static IP addressing and was able to ping the DHCP server. You also mentioned that you ran wireshark on the windows DHCP server and saw no DHCP traffic from the client. That means that the client's Ping (unicast) is getting to the DHCP server; but the Client's Discover (Broadcast) is not. Pease verify the IP-helper addresses are correct and that they are on the right interfaces.

let me know if I read and understood correctly, what you wrote.

HTH
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[koverpeck]

I manfully reviewed and configured the new switch. IP helper is configured properly on the vlans and the I can ping the helper address using each vlan as the source.

interface Vlan96 (Data)
ip address 10.117.7.1 255.255.255.192
ip helper-address 10.100.5.23
!
interface Vlan172 (Voice)
ip address 10.117.7.129 255.255.255.192
ip helper-address 10.100.5.23
!
interface Vlan999 (Guest)
ip address 10.117.7.65 255.255.255.192
ip helper-address 10.100.5.23

Topology below has a core switch labeled and this is the device in question that is being replaced.

[Reza Sharifi]

Can you post the output of "sh run" and "sh ver" from the new switch?

HTH 

[koverpeck]

Show run of the replacement switch and router attached.

[MHM Cisco World]

Hi Friend are this issue still not solved ??

[NetworkDave]

@koverpeck,

Thank you for the information.

Please provide the configs/routing for the core switch and remote router. [It seems @Reza Sharifi and I were thinking the same thing.] 

Also, are you able to do a packet capture on the output of the core switch?

HTH
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[koverpeck]

I am not able to do a packet capture do to site support constraints and when the replacement switch is in place it causes production issues.

[Reza Sharifi]

The core switch config looks good. Since you are not using EIGRP anymore, does the local router have a static route for all the vlans pointing to the switch IP?

For testing, is there a change if you remove the access-group 14 from vlan 999?

HTH