aironet 1600 dhcp issue

[michaelmartone]

I have 9 standalone AIR-SAP1602I-A-K9  (Aironet 1600) that have worked fine for 2 years.

The last few weeks many people (but not all!) are complainging that they are not getting an IP address via DHCP from the WAPs.

They are connecting to the 1600 but not receiving an address. This is particularly problematic in mobile devices (phones/tablets) but some laptops as well. We are not out of IP addresses on the DHCP server. When I put in a test NetGear WAP on the same network everyone can connect no problem.

The network is flat 10.18.76.0/24 and the file server is the DHCP server not the WAPs.

The fact that it is not every device is making it difficult to troubleshoot. I checked the basic config of each WAP and they appear to be configured the same. We have 3 on each of 3 floors. 

System Software is:  15.2(2)JB

Any ideas?

[Charles Hill]

Since its not isolated to a end device or ap, I would start at the dhcp server.

I would create a monitor session on the swtichport that connects the dhcp server to your network.  Do a packet capture, then filter the packet capture on the mac address that is trying to obtain an ip address.

See if the dhcp discover packet is getting to the dhcp server, ....

Should see dhcp discover, dhcp offer, dhcp request and dhcp acknowledge.

[michaelmartone]

Interesting - 

All along I assumed it was DHCP but that is not the case.

I assigned my laptop a static IP in range and went to the 1st floor where most of the problems occur. I was connected to the WAP but could not get to any URL or IP address. In other words no IP traffic is passing once I am connected. Apparently it is only a few of the WAPs and not all - downstairs there are 2 out of 3 working.

Any ideas on what might cause this?

[Charles Hill]

Does "show log" on the AP show any errors?

Can you browse to and login to the AP?

Are all interfaces up?  show ip int brief

Can you ping the gateway from the AP?

Is the switch port and the AP interface speed/duplex set the same?  Auto - Auto

Does show log on the Switch, show anything concerning the port connected to the AP?

[michaelmartone]

I see these Warning messages:

Packet to client 48d2.247d.c05f reached max retries, removing the client
Packet to client a4db.30d2.0e3b reached max retries, removing the client

[a4db is one of the PCs that lost connection]

I am able to ping the DHCP server from the AP

[Charles Hill]

This is usually a result of a noisy RF environment.

Try a busy carrier test to reveal if your environment is noisy.

The link below describes the test commands.

https://supportforums.cisco.com/document/11121/error-message-user-receives-packet-client-000bcd5a35d4-reached-max-retries-removing

[michaelmartone]

The only thing that gets me back online once I drop is to disconnect/reconnect.

[Charles Hill]

Have you rebooted the ap?