ArubaOS and Controllers

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Contributor II

Troubleshooting slowness and frequent disconnects

I am running a M3 controller with ArubaOS 5.0.4.1 with AP-105s. I have HT enabled on the 802.11a radio, but disabled on the 802.11g radio due to a fairly high (and increasing) density. We have 6 SSIDs currently, but we are working to consolidate some of them. However, I believe we can only get to a minimum of 4 right now. Nonetheless, the beacon period is set to 100ms and beacon regulate is turned on. Some of the smaller SSIDs (VAPs) have deny broadcasts enabled. But, the largest VAP does not. The largest VAP has upwards of 1,000 associations. Max associations is still on the default at 64. Most of the VAPs are WPA2-PSK-AES. However, the largest VAP is WPA2-8021X-AES.

My questions are what troubleshooting steps would you take to troubleshoot a report of "slowness" and what troubleshooting steps would you take to troubleshoot a report of frequent disconnects/reconnects.

Sometimes I am able to see packet loss or interfering APs in the area. But, most of the time, the client count of the AP, bandwidth utilization on the AP and subsequent switch port, latency is almost non-existent and the signal strength of the client is superb. We have Airwave as well and it usually corroborates the excellent environment information. In fact, the aggregate wireless bandwidth is usually 40 Mbps. So, bandwidth is not high across the entire network much less an individual AP.

The slowness reports typically come while using our Citrix applications. So, of course, I have our Citrix administrators always engaged so they can tell me whether there are any issues with the servers. Of course, they can never find anything either. So, I just want to be sure I am covering all my bases.

The frequent disconnects/reconnects seems to happen to the same people over and over again. So, they may be client issues. But, of course the users claim to not have any problems on other networks (some WPA2-PSK and some WPA2-8021X).

Any help is appreciated. I have been crawling the documentation and KB for help.
Guru Elite

Re: Troubleshooting slowness and frequent disconnects

You need drop broadcasts on ALL Virtual APs, to make a difference. Try that.


Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Moderator

Re: Troubleshooting slowness and frequent disconnects

Do you happen to notice that it is only 2.4Ghz clients that this happens to or does it happen to clients on both bands? If 2.4Ghz only, could be intermittent noise? If not, wondering if users are roaming when they see the disconnect. You could look at "show auth-tracebuf mac " to see if they are.
Contributor II

Re: Troubleshooting slowness and frequent disconnects

I am going to go ahead and drop broadcast traffic and test. As for the roaming, they are sitting in one place when the disconnects occur. IIRC, they are mostly on 5Ghz as we have band-steering enabled and most of these are really new laptops that support 802.11n.

Last night I cleared the counters on both of the fiber ports to see how many broadcasts I am receiving and this is what I show:

gi0/0
281911278 packets input, 2380255737 bytes
Received 10752489 broadcasts,

gi0/1
129024127 packets input, 4263651750 bytes
Received 4167549 broadcasts,

I will let you know how that works. Thanks!
New Contributor

Re: Troubleshooting slowness and frequent disconnects

I will say denying broadcasts in my environments had made a world of difference. I had been experiencing the exact same symptoms as you had described, in a similar topology. Multiple SSIDs of varying encryption and authentication, a fair density to where no bottlenecks were observed from a controller or AP standpoint. I even had Aruba come onsite and they did heavy spectrum analysis (We are not on 6.X code and do not have new enough hardware for native specturm analysis). Everything appeared to be fine. Once I dropped broadcast on the SSIDs, it was absolutely night and day as far as the difference in performance goes. I have numerous sites where the connecting clients are in a /16 subnet, so as you can imagine, we have a significant amount of broadcast traffic at some of our locations. In fact, one of our locations' 3600 series controller would frequently crash reporting watchdog timeouts. Since dropping broadcast, the controller had been rock solid. Just figured I would share a similar experience.
Contributor II

Re: Troubleshooting slowness and frequent disconnects

Thanks all! Thanks for sharing Andy. We have /20 subnets so not as large as yours, but not small either. I just turned off broadcasts on the main/largest SSID. We will see if this helps as expected.

I really cannot wait until we can move over to 6.x. We just need to let it bake a bit longer as we are an academic healthcare institution and cannot afford to be anywhere near the bleeding edge. :D
New Contributor

Re: Troubleshooting slowness and frequent disconnects

I'm thinking about doing this. We are not using the controller for DHCP. Will the drop broadcast and multicast prevent DHCP from working? I have the ip-helpers configured.
Guru Elite

Re: Troubleshooting slowness and frequent disconnects

Arp and dhcp are excluded.


Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

New Contributor

Re: Troubleshooting slowness and frequent disconnects

Thanks. I figured that would be the case, but just wanted to bounce that off the group.
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