Slow wireless connections

[rschwart]

We recently did a forklift upgrade on our campus and installed 3502i's, 3502e's, and 11 5508 WLC's. Our students are complaining about slow connections in several areas of the campus.In our testing and basic trouble shooting our Apple laptops have no problems but our windows laptops are showing a very slow connection rates 264kbps downloand and 366kbps upload. The window device has current drivers installed. Has anybody else encountered this?

[blakekrone]

What kind of security settings are you using? Have you performed a survey of some of the areas in question? How close are the APs together? What data rates are enabled? Which frequency band?

[rschwart]

We are using WPA2+AES with 802.1x Authenication. The ap's in some areas are close together in auditoriums( the power is turned down to the lowest level), All data rates are still at the default settings. The devices are showing connect to G but not sure what frequency.

[rschwart]

In the auditoriums I was considering using channels 1, 4, 7 and 11 to see if this may make a differance.

[blakekrone]

That doesn't give you anything, that hurts you. Stick to 1, 6, and 11.

You would be better off disabling the 802.11b data rates if possible to reduce the overall size of the cell and channel utilization.

Are these a mixture of windows client devices or are they a standard config issued to the students?

[rschwart]

I've used the check box in 5508 to disable b and leave g enabled with not very good results, cell phone and a a few laptops could not connect to the wireless. My thought was to disable 1 and 2 Mbps, to see if that would help on the b channels. The students devices are byod.

[blakekrone]

I would disable 1, 2, 5.5, and 9, leaving only 11 for 802.11b support.

With them being BYOD all bets are off, who knows what applications have been installed on their systems that are messing with things (symantec firewall, etc).

You are also going to have such a mixture of good cards (Intel) with horrible cards (Dell TrueMobile).

[Stephen Rodriguez]

You should be able to disable everything below 11.  This would still allow a b client to connect, but stops them from ratcheting down to 1 or 2 Mbps.

Was a sight survey done?

Steve

[Leo Laohoo]

In our testing and basic trouble shooting our Apple laptops have no problems but our windows laptops are showing a very slow connection rates 264kbps downloand and 366kbps upload.

Wow.  That's slow!  How many laptops were concurrently connected when you took these readings???

[rschwart]

I'll disable 1 thru 9 and leave 11 at mandatory in my test bed and see how that goes, before I push it out.

Yes we had a sight survey done, which I had to revist due to the contractor indicating 2 ap's for all the auditoriums 540 seats total, That was revised to 4 ap's per room, we are seeing @130 users online pre room. In out testing only 4 other clients were the ap. All ap's have a gig back to a 3750X with a gig connection to the building 6500 and the 5508 have an 8 gig connections to 6500's.

[Leo Laohoo]

Yes we had a sight survey done, which I had to revist due to the contractor indicating 2 ap's for all the auditoriums 540 seats total, That was revised to 4 ap's per room, we are seeing @130 users online pre room. In out testing only 4 other clients were the ap. All ap's have a gig back to a 3750X with a gig connection to the building 6500 and the 5508 have an 8 gig connections to 6500's.

Wow.  That's one lousy contractor doing the site survey.  2 WAPs for >500 possible users is a laughable result.  I hope you can still get a refund.

With this kind of over-saturation, it's best to leave some WAPs with their 802.11b/g radios on and some turned off.  You'll need to depend entirely on 802.11a radio for this.

What kind of wireless traffic do you forsee?  E-mails?  Video streaming?  Voice?  Web?

[rschwart]

Most traffic should be web and e-mail. Students do stream youtube and instructors are using unusually large images, they request students to review. That is a good idea I had not thought of, splitting up a and b/g wap's. I'll keep the thread posted with the results. I'll be sittng in on the class next week to get an idea of what is going on actually in the room.

[rschwart]

Still working on this. After reading some other information, it appears that Intel and a few other nic card manufactures prefer that WWM (WiFi Multimedia) be allowed on the vlan. So I have allowed WMM and enabled ClientLink as well.

[rschwart]

Students are still having connections issues, extremely slow connection rates, downloads time out, etc.

[Justin Kurynny]

rschwart,

Firehose of questions for you:

Per an earlier post, are you still seeing that Apple clients have few issues but that Windows clients have considerably more? Have you personally seen Apple and Windows clients downloading side by side yet with different results?

What are your WLC logs indicating? Have you tried any client debugs for known problem client MAC addresses?

Are the problems sporadic throughout the day or consistent all day long?

Is the problem only affecting wireless, or can you reproduce the slowness on wired clients? If you plug a PC into a wired port on the same switch where you have a problem AP, is the PC able to pull traffic from the network smoothly, without delay and without dropped packets?

Do any of your switchport uplink interfaces (anywhere on the backbone between the problem AP and the server farm / Internet) indicate dropped packets?

Look at your AP controller association times. If they're short associations, you may be seeing CAPWAP control traffic starvation, which is going to cause periodic AP deregistrations and the failed AP's clients reassociating to nearby APs.

Is the issue affecting Internet traffic only, or if students download content from on-campus servers, do they have problems with that, too? Is your Internet connection oversubscribed?

Is spanning tree stable on your network (no/few topology changes)? What spanning tree protocol are you running? (This question perhaps sounds unrelated, but L2 issues, esp with STP, will mangle upper layer transactions. I've seen this particular issue several times on larger campus networks).

Justin