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Troubleshooting AP1815W-B-K9 to that can't join 5520 WLC

Level 1
Level 1

I have a AIR-AP1815W-B-K9 that can't join my 5520 controller. What's weird is that it joined on my test switch in office. When I bring it to the edge switch, it won't join.....switch config is all correct. POE etc is all correct.

I attached the log of the AP when it is trying to join after a factory reset. Any one know how I can get it working? It seems like it's not getting an IP from the WLC. But it did in my office.

8 Replies 8



                  >.. It seems like it's not getting an IP from the WLC.
             - IP address must come from a DHCP server , not the WLC ,


-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
    When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '

Rich R

And if it's not on the same subnet as the WLC (which it sounds like it's not) then you need a discovery method for it to find the WLC - preferably option 43 configured in the DHCP.  The routing also needs to be in place for them to talk to each other.

They are in the same vlan. I have the exact same switchport on my test switch in my office. The AP joins the WLC and comes online there. But on the edge switch, it just gets stuck on flashing red. On that edge switch, there are two other APs with the exact same set up. What I did not mention, this AP stopped working after some POE device was plugged into the LAN1 port on the AP. It seems like it remembers the edge switch or something like that. Still doesn't work after factory resetting AP. I have that console cable for this AP. I think I'm gonna send the log to cisco.

If it's on the same subnet it will discover the WLC by broadcast.
So you just need to work out why the DHCP isn't working:
- is the VLAN trunked to that switch
- is the port correctly configured and in that VLAN?
Get a packet capture on the switch port to see what's happening.  If you see the AP sending the DHCP discover but no offer coming back then it's an upstream problem blocking the DHCP somewhere on the network between the AP and the DHCP server or relay.

Ok, may be a stupid question, if the AP is unable to get an IP, how do I filter the packet capture? MAC address? Yes the vlan is trunked, there are two other APs on that switch. They all have the same set up (same vlan) and they work. Switchport is correct. Same as the other two that work.

Rich R

Assuming it's a modern catalyst switch running IOS-XE:
SWITCH#mon cap pcap match ?
any all packets
ipv4 IPv4 packets only
ipv6 IPv6 packets only
mac MAC filter configuration
pktlen-range Packet length range to capture
If it's some other switch then the commands may be different.

Ok I will try, I thought you meant using packet capture. I will try those commands. It's a C9200L-48P-4X.

That is how you do a packet capture <wink>
SWITCH#mon cap pcap match any interface Gi1/0/1 both buff size 10 start

Use "sh mon cap pcap buffer brief" to see what you have captured.
then "mon cap stop"
then "mon cap pcap export bootflash:mycapture.pcap"
then copy the file from bootflash.
When you're done "no mon cap pcap"

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