Users unable to get IP address after several months running normally!

[flavio_borup]

My ZD is 9.9.0.0 build 216 and i can ́t do any change right now
I have several old APs which doesn ́t allow me to upgrade

I ́m running this very same solution in the last 3 years with no problems at all

Yesterday, some users complain about the were unable to get IP addresses

My DHCP Server is a Windows 2012
My Ruckus environment have 12 APs and several SSIDs and Serveral VLANs
My network uses HP/3COM Switchs models 2600, 5550, etc


After doing a investigation:

The problem only affected a single SSID and is related to a single VLAN
At DHCP Server logs, i can see SOME clients are still able to get IPs, but randomly, some users can ́t. After some network tracing, i can see DHCP requests arriving at DHCP Server and all requests that come to DHCP are served with no problem. 

But the clients with problems, the DHCP request does not arrive at the interface, for some reason, the traffic was blocked at some point and the DHCP packets were not arriving at the DHCP Server.. Again, for some clients, other can connect with no problem.

Yesterday, afet several months of uptime i rebooted my ZD and all things got normal again. Ok, maybe it was a "glitch", anyway, after the reboot.. everyting got back normal

Today, the problem is back! After some tests i did the following: I changed the VLAN ID of the SSID and clients were able to get IP address again (each VLAN has its own IP range), so, in the new range, things were nromal. And, after re-configuring back as before, the problem was gone. First a reboot, now a little change in configuration to solve the problem. Weird!

Some monutes ago, the problem is back again! and i didnpt reboot yet, but now, no matter what change i do, the problem is here, some clients can leas IPs and some not (randomly) and if the pacjets arrive at DHCP Server they ́re leased with no problem, but some packets simply didn ́t arrive at the DHCP Server interface to be processed

So, what ́s next? What should I do?

[andrew_giancol1]

also, perhaps we'll need to use br0 or the wlan your client is failing on.

lacking the pcap from the AP you can run wireshark directly on the server. Are you forwarding  DHCP requests via IP helper, or is your dhcp on the same subnet?

[flavio_borup]

After trying the "ANY" interface, i ́m able to see packets and now i ́m filtering by "Bootp" and i think, for now, that i ́m able to start diagnosing something

[andrew_giancol1]

Excellent! Just remember, to make sure your eth interfaces on the computer your using aren't selected.

Best of Luck Flavio!

[flavio_borup]

Now, going on by the main/original subject:

I ́ve applied a filter based on DHCP Transaction ID : (bootp.id == 0xd585f0f8) && ((bootp.option.dhcp == 1) || (bootp.option.dhcp == 5))

I can see 5 DHCP Discovers, clearly showing wifi client trying to get an Ip address, but for now, i have no idea on where the hell is going on

To where are these packets going? If there was a rogue DHCP Server, should I see the (rogue) dhcp server packets responses? SO, i ́m 99% sure that there is no rogue DHCP operating in the segment

Is consistent, client can get an IP and packets are no arriving at the DHCP Server (i can see that ncapturing packets at the real DHCP Server)

Packets are getting lose on their way...

[andrew_giancol1]

ok so you're looking for the server to ACK or NAK these replies. do you see that?