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Occasional Contributor I
Posts: 6
Registered: ‎06-08-2007

AP Down

Many times after rebooting one of our controllers for firmware upgrades, there will be a few APs that do not come back online. They show status as "AP down". The APs worked fine prior to the reboot.

Removing power and reapplying sometimes works, but generally not always. After removing power with no luck, we replace the cables, but still generally no luck. The AP (in this latest instance, AP-65s), show two green lights "on" on the "PWR" & "ENET" LEDs, but not on the "A" & "BG" LEDs.

What tricks (commands) are available to bring a down AP back up?
Occasional Contributor I
Posts: 9
Registered: ‎04-03-2007

Re: AP Down

I would suggest using the Y serial splitter along with console and rebooting the AP. You'll want ot watch and see at what point the AP reboots (Get IP address, able to contact master...). We've seen this a few times, but not enough to be concerned with. What version are you running?

-Garrett
Wireless Eng. OSU
Occasional Contributor I
Posts: 6
Registered: ‎06-08-2007

Re: AP Down

Running version: ArubaOS (MODEL: Aruba6000-US), Version 3.3.1.22

Funny that you see it a few times and are not concerned about it -- we see it every time we reboot one of our controllers. Booted one last night to do firmware upgrade, now I have 5 APs that won't come back online. Removed and reapplied power, but still nothing.

Don't have a Y serial splitter cable.
Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: AP Down

Can I ask what type of switches those AP are connected to?
Occasional Contributor I
Posts: 6
Registered: ‎06-08-2007

Re: AP Down

Cisco 2950 & 2970s:

IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(22)EA2, RELEASE SOFTWARE (fc1)

IOS (tm) C2970 Software (C2970-I6L2-M), Version 12.1(19)EA1d, RELEASE SOFTWARE (fc1)

There are other APs on the same exact switches that are continuing to work just fine after the reboot.
Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: AP Down

I'm curious, do you see any input errors on the switch ports that the problem APs are connected to?
Occasional Contributor I
Posts: 6
Registered: ‎06-08-2007

Re: AP Down

Nope ...

sh int fa0/48
FastEthernet0/48 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0013.607c.2930 (bia 0013.607c.2930)
Description: ]
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 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 02:35:24, output 00:00:01, output hang never
Last clearing of "show interface" counters 9w6d
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 34000 bits/sec, 16 packets/sec
40912261 packets input, 2611677374 bytes, 0 no buffer
Received 20 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 3 multicast, 0 pause input
0 input packets with dribble condition detected
145320584 packets output, 4252423030 bytes, 0 underruns
0 output errors, 0 collisions, 2 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
Guru Elite
Posts: 20,761
Registered: ‎03-29-2007

What you can do

Do "show ap database | include Down" on the commandline.

The APs that are down might have a flag next to them that says WHY they are down. If that doesn't work, do "show datapath session table " periodically to see if the AP is even attempting to contact the controller, and on what ports. You then might want to do a "show log system all | include " to see if there is a reason why the AP is being rejected, rebooting, etc from a system standpoint. (It could be that you don't have enough licenses on that controller, maybe?)

Last but not least, make sure there is no firewall blocking traffic between those access points and the the management IP of the controller.

If you open a case, of course, support can give you a much better idea.


Colin Joseph
Aruba Customer Engineering

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Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: AP Down

I'm surprised there are no input errors. APs send jumbo frame discovery packets to the controller using 1590 byte packets, which show up as input errors if the switch doesn't support baby giant or jumbo frames. Sometimes, as in one of my installations, the switch port didn't like the discovery packets and was causing the AP to drop offline. I dropped the AP MTU to 1420 to avoid the jumbo probing.
MVP
Posts: 498
Registered: ‎04-03-2007

What we do

First off, we (Ohio State) are, of course, "concerned" when APs don't come back up. However, when comparing a few isolated down APs to other issues we've encountered over the last several years, it does not stand out as a 'large problem' --- that is essentially where Garrett was coming from.

Colin is inline with what we do. I generally follow the process that the AP would take:
- Check for link connectivity on switch
- Check if mac address has been learned on switch port
- Perform shut/no shut on switchport (especially useful for POE switches)
- Check DHCP logs to see if it pulled an address
- Run "show datapath session table " to see what traffic, if any, is getting to the controller. Ideally, you'll see protocol 47 (GRE) along with UDP 8211 (PAPI)

Many times with APs, however, the information needed is on the AP itself. Unfortunately, Aruba engineering has yet to implement a mechanism for the AP to keep a small buffer for the purpose of retaining the last few lines of logs -- instead, they are cleared when the AP goes down. :(
==========
Ryan Holland, ACDX #1 ACMX #1
The Ohio State University
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