Giuseppe Larosa Fri, 01/09/2009 - 13:04

Hello Mike,

the CDP process might be not running properly on access point

or if the switch port is a trunk verify what is the native vlan and if it is permitted on the trunk and in STP forwarding state.

CDP should use the native vlan.

Hope to help


Giuseppe Larosa Fri, 01/09/2009 - 14:40

Hello Mike,

I see that you see other APs as CDP neighbors.

what is the config of the switch port where the missing neighbor is connected ?


sh run int fx/y

sh int fx/y switchport

And as John suggests what is the config of the access point (but it may be controlled by WLC as I see in your sh cdp nei)

Hope to help


mike.abrahams Tue, 01/13/2009 - 10:05

Here is the sh run on

interface FastEthernet1/0/20

description Access Point Vlan

switchport access vlan 3526

switchport mode access

spanning-tree portfast


mike.abrahams Tue, 01/13/2009 - 10:06

Here is the sh inter:

BU111371#sh interface fastEthernet 1/0/20

FastEthernet1/0/20 is up, line protocol is up (connected)

Hardware is Fast Ethernet, address is 0021.d7a1.3f16 (bia 0021.d7a1.3f16)

Description: Access Point Vlan

MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s, media type is 10/100BaseTX

input flow-control is off, output flow-control is unsupported

ARP type: ARPA, ARP Timeout 04:00:00

Last input never, output 00:00:03, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

291889 packets input, 40719292 bytes, 0 no buffer

Received 7121 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 0 multicast, 0 pause input

0 input packets with dribble condition detected

1738790 packets output, 862937791 bytes, 0 underruns

0 output errors, 0 collisions, 3 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 PAUSE output

0 output buffer failures, 0 output buffers swapped out

Giuseppe Larosa Tue, 01/13/2009 - 11:25

Hello Mike,

I don't see any trouble on your configuration of the switch port.

I would try to restart the access point to see if anything changes.

Being the port an access port there no troubles with trunk encapsulation or native vlan mismatch.

Hope to help


joemhemail Tue, 01/13/2009 - 16:04

I had a 2620 fast ethernet interface that would not send out cdp packets nor any multicast packets except those in the range of

It was a hardware failure.

Best regards

glen.grant Tue, 01/13/2009 - 16:15

Try doing a clear interface on both sides of that link . Have seen this before on some older 2924's and that fixed it for some reason .

Leo Laohoo Tue, 01/13/2009 - 20:50

Is CDP enabled on the AP (global and interface configuration) and the interface of the switch it's connected to?

mike.abrahams Wed, 01/14/2009 - 04:22

Leo Laohoo

That was it !

The CDP was NOT enabled on the 802.11b/g side on the AP

Pravin Phadte Wed, 01/14/2009 - 04:32


I see WLC controller in CDP neig.

Are these AP LWAP ?

If so you may need to enable cdp from WLC.


> On top click on wireless

You will see the APs names.

> Click on the AP which is not in CDP

> Click on advance

and you will find the cdp enable click.

hope this helps

lamav Wed, 01/14/2009 - 11:22


At the risk of sounding like a wise guy, Giuseppe suggested you look at the CDP config on the AP 5 days ago -- when you first started this thread.

Replied by: giuslar - Senior Network Engineer, Italtel S.p.A - Jan 9, 2009, 1:04pm PST

Hello Mike,

the CDP process might be not running properly on access point...


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