Access-Point going up/down

[cisco.kid111]

Hello All

We got Issue with One Access Point [ model - AP1242AG ] - it goes up/down.  Users connected on this Access Point get disconnected or time-out connecting to Server. The access-point was installed around 3-4 weeks back. We checked the cable connecting to the Access Point but didnt notice like disconnected or time-out.

[ Access Point was configured with these options ]

AP Name -  JD1

status - Enabled

AP mode - Local

IP address - Static

No of Radio Interface - 2

802.11 b/g/n

802.11 a/n

which debug command will help to identify the issue or GUI option

thanks in advance

Cisco Kid

[George Stefanick]

Kid,

Is this connected to a WLC? If so, click on the wireless tab and then select the AP and on the bottom right there are 2 counters. AP UPTIME and CAPWAP UPTIME.  Report back what that is ...

If this is an automous ap, do a show ver and what is the uptime .

[weterry]

Can we get a better description of what Up/Down refers to?

I'm guessing the "AP Mode - Local" implies this is WLC based. If that is the case, then I'd start with what George mentioned, we need to know what AP Uptime is, as well as AP Associated time.  

Might not be a bad idea to get AP log (syntax is something like "show ap eventlog ") or you can telnet to the AP directly.

Either way, from my point of view, we need to define if you are dealing with physic up/down of the AP (reboot/crash),  if we're talking up/down of the Radio (radio resets?), or if  up/down is just implying that users work and then they don't work (a million and one reason for that)....

[cisco.kid111]

Hello All

The Access Point is connected to WLC. When a user is connected to this particular access point users notice packet loss ( ping timeout ) to any host. When I goto WLC GUI > Monitor > Access Point Summary  ; I see the Total number of AP changes from 6 to 5 . In total we got 6 access point.

How do i reset just the radio's.

Thank You

Cisco Kid

[Scott Fella · Accepted solution]

The AP is loosing its connection back to the WLC. So if you have ruled out the cabling including patch cords on both end, take a look at the switchport for errors. How you reset the radios for that AP, you might as well just reboot it and see if that helps.

Sent from Cisco Technical Support iPhone App

[George Stefanick]

Hey Kid,

As Scott pointed out the CAPWAP tunnel thats is bulit between the AP and the WLC is breaking.

UP time is the time the AP has been up (powered on)

Controller associated time is the tunnel ...

[cisco.kid111]

Hi All

I restarted the Access Point and will see what happens. Our Access Point and WLC are in the Same VLAN.

WLC is connected to Layer3 switch and the port is configured as Trunk port with additional command switchport trunk native vlan 12.

The access point ports configured are also configured as

switchport mode trunk

swichport trunk native vlan 12

Are these configuration correct for controller and Access Point.

The following is the show interface output where the AP is connected

sh interfaces fastEthernet 0/9

FastEthernet0/9 is up, line protocol is up (connected)

  Hardware is Fast Ethernet, address is 0021.a1d2.ee09 (bia 0021.a1d2.ee09)

  Description: **AP3**

  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 00:00:40, output 00:00:00, 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 518000 bits/sec, 130 packets/sec

     25673274 packets input, 5670744879 bytes, 0 no buffer

     Received 2413785 broadcasts (0 multicasts)

     0 runts, 0 giants, 0 throttles

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

     0 watchdog, 557119 multicast, 0 pause input

     0 input packets with dribble condition detected

     16665439077 packets output, 10663148678995 bytes, 0 underruns

     0 output errors, 0 collisions, 1 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

[Scott Fella]

Looks fine... Just monitor the ap and if you see errors on the switchport.

Sent from my iPhone

[George Stefanick]

Best pratice is to put the access points on switch port access, not trunks.

[cisco.kid111]

Hello George & Scott

Thank you both for supporting

Can you plz check this configuration for my setup

4507--------------------------WLC

Config on 4507 for WLC

vlan 12

interface vlan 12

ip address 172.20.16.1 255.255.255.0

ip helper-address 192.168.2.100

interface GigabitEthernet2/7

description "Terminated-to-WLC"

switchport mode trunk

swichport trunk native vlan 12                // Do I need this command

Access-Point are connected to another Access-switch 2960,

interface GigabitEthernet 0/0

description "Terminated to 4507"

switchport mode trunk

interface Fa 0/9                   // AP is connected

switchport mode trunk

swichport trunk native vlan 12

The Access Point is configured with static IP and default-gateway i.e 172.20.16.1

[weterry]

I don't think "To trunk or not to trunk" is going to cause your AP to drop its connection to the WLC randomly. Especially not just one. If it were me, I'd be focusing on if

A) network connection to the AP itself is going down (ping the AP, telnet to the AP, confirm everything is is working with this AP network-wise),   

B) any errors on the AP log give indication of why it is disconnecting.  If you look at the log on the AP and you see anything about max retransmission then it implies packets between the AP and the WLC must be getting lost somewhere randomly.....

So, since you say only 1 AP is doing this:   Is there anything special about the network path to that AP compared to others?

Perhaps a simple switch APs to see if the problem follows the AP is in order or stays in the same area,  is in order?

[cisco.kid111]

Hello Weterry

What you mentioned is correct that trunk has nothing to do with AP up/down.  I only wanted to ensure the basic connectivity configuration is correct.

After I restarted the AP so far it looks ok but need to wait and see more. which debug commands on AP you recommend

thank you

Cisco Kid

[weterry]

Fair enough.

Local mode AP should be connected to an Access port, as they don't trunk. HREAP you'd typically trunk.

WLC should be connected to a trunk port.  If you define Native Vlan 12 (Management?), then your Interface that maps to that should say vlan 0 (unless your switch is tagging the native vlan).

I still suggest you look at the eventlog on the AP to confirm why it was disconnecting (I assume MAX Retranmsissions).

Typcially, if this were a TAC Case and a max retransmission problem, you would be checking to see whose packets are getting lost where (packet capture at AP switchport and at WLC).    But you could always start with "debug capwap client mgmt" on the AP (I think that is the syntax).    SOmething like that debug anyhow should show the capwap mgmt traffic   (keepalives for example)  and it would give indication how often it is retransmitting packets, and if that coorelates to the AP disconnect.

-Wesley Terry

[George Stefanick · Accepted solution]

To piggy back on Wesley's comments.

Access points in local mode are switch port access. The only time you would trunk on a WLC AP is when you do HREAP and you separate vlans.

On the WLC switch port it was stated to use native vlan in all the config guides till 7.x. The 7.x guide was corrected and states to tag all vlans (management included). If you configure a native vlan and you trust CoS you will not be trusting management traffic as its not tagged traffic. Whereby, a policy map will be needed. 

If you tag all traffic, trust CoS will trust all traffic.

I was at Cisco Live in July and at the CCIE wireless class and I asked this very questions. Javier said "always tag the management interface" .

[Leo Laohoo]

How is the AP powered?  Let me hazzard a guess that it's powered using an injector or a power cube?