Download speed limited to 802.11g when n should be possible

[IanMurphy]

I have inheirited an installation consisting of an AIR-CT2054 with a number of AIR-CAP1602I-E-K9s.

A number of users have been complaining that their upload/download speeds maxes out at around 54MB/s and this seems to be the case with all of the antenas, regardless of how close I am when I test this.

From the wlc, under Wireless>All APs > select one AP from the list > advanced 

I can see that Regulatory Domains contains 802.11bg:-E and 80211a:-E (i.e no n)

Configured country code is ES (I'm in spain)

Wireless> Radios > 802.1b/g/n, the list shows that all APs are using Radio Slot# =0

Wireless> 802.11a/n/ac>'High throughput'  indicates that 11n Mode is enabled and on the right it indicates speeds up to 217Mb are supported

But, Wireless > 802.11a/n/ac>network only shows data rates from 6 to 54 and nothing faster

Wireless > 802.11b/g/n>network only shows data rates from 6 to 54 and nothing faster

Wireless > 802.11b/g/n > High throughput is, again, shows speeds of up to 217Mb as supported

So, whats going on? The regulatory domain seems to only support up to 802.11g

Apart from the Reg Domain, 802.11n should be working, but something seems to be disabling it.

I have been through the article Troubleshooting 802.11n Speeds - Cisco Community, but nothing seemed to be identified by that article. Unfortunately the article refers to a different model with slightly different software. It also shows complete output from commands and says that the setting can "be verified using this command output" without indicating which options are relevant. Since the output is different, its difficult to compare.

Any idea what this could be? I didn't configure this system and its been in place for quite some time so I have no idea what has been modified over the years. It *seems* to have a fairly standard setup with most options being the default.

any help/suggestions appreciated

Ian

[Leo Laohoo]

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@IanMurphy wrote:

A number of users have been complaining that their upload/download speeds maxes out at around 54MB/s and this seems to be the case with all of the antenas, regardless of how close I am when I test this.

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What wireless client is used to test this "54 Mbps"? 

What firmware is the WLC running on?

Has anyone done an end-to-end check, like look at the switch ports, line errors, network congestion, speed of the uplink, etc?

[IanMurphy]

A number of laptops and mobile phones all report the same figure. If it was a limitation of a switch port or a trunk interconnect then the speed would max out at, say, 100Mb, or the speed of an ISP fiber connection. All tests are fairly consistently reporting in the 54Mb range.

The firmware is old - 7.6.120.0

If you connect a PC to the same switch as one of the antennas and do a similar test, the speed will max out around 300Mb - the ISP speed. This is sharing the same switch<->switch trunk and the same ISP fiber.

Since making my post I have found something which may be influencing the speed. 

Wireless > 802.11a/n/ac > RRM > DCA > channel width is currently set to 20Mhz

I'm going to switch this over to 40 as soon as a presentation is over and I can do this without affecting users.

[IanMurphy]

What effect do the DCA channels have? For 802.11a/n/ac I have channels 36-64 enabled, but the check boxes for channels 100-124 are not marked.

This would seem to be the correct setting as far as I can tell.

[Leo Laohoo]

Firmware is 7.6.120.0? 

Geez.  I do not have any recollection on how this firmware behaves. 

Are the wireless clients confirmed to be on 5.0 Ghz?

[Rich R]

Well that is VERY old software ...

Presume you have all the MCS rates enabled?

https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-2/config-guide/b_cg82/b_cg82_chapter_010111.html#ID1326

[patoberli]

The 1602 series AP is an 802.11n series model. That means, with a 40 MHz channel width (more is not possible on 802.11n) the absolute maximum theoretical connection speed is 300 Mbit/s, which in reality means 150 Mbit/s of throughput. That is if there is no noise, no neighbor Wi-Fi, etc. 

If you have a Windows client, please open a cmd and enter the command: netsh wlan show inte

Then please post the output of the following lines:

Receive rate (Mbps) : 400
Transmit rate (Mbps) : 400

This is the connection speed/rate. The real throughput will be about 40-60% of this rate. If you only see 54 there, please output the full result of the previous command.

For 802.11n to be usable, make sure you use WPA2 with AES (no TKIP, no WPA1) or Open. Also make sure that WMM is allowed on the SSID.

[IanMurphy]

thanks for all the info guys. 

Unfortunately I have been unable to do anything with this as the APs are being used in events rooms for presentations and it seems they never stop. They've been going on all day for the last few days. Looks like I'm going to have to make this change remotely one evening.

I have a related question. A while back we upgraded some old core switches with new C9300s. At the time I remember seeing something which implied that they can funcion as WLCs. 

Is that the case or was I confusing it with something else? If it is true, how do I work out which models of new APs are compatible with the 9300.

I would assume that the CT2504 is now obsolete, but can its firmware still be updated to support newer APs even though its out of support? Is it even worth doing?

If not, can the old CT2504 be replaced with, a latest and greatest two node WLC cluster. Would the allow me to move the 25 node AP license from the CT2504 to the new WLC, or do I have to maintain two WLCs, one for the 'old' APs and another for the new ones?

I've only ever dealt with smaller installations which have never upgraded anything, so I'm unsure of whats comercially possible.

[Leo Laohoo]

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@IanMurphy wrote:

Unfortunately I have been unable to do anything with this as the APs are being used in events rooms for presentations and it seems they never stop. They've been going on all day for the last few days. Looks like I'm going to have to make this change remotely one evening.

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Sez who?  Is the WiFi being used at, say, 4am?  On a Saturday? 

I upgrade WLC firmware outside business hours.  I do not have to "be there".  I can schedule the WLC to reboot at a future time/date.  

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@IanMurphy wrote:

A while back we upgraded some old core switches with new C9300s. At the time I remember seeing something which implied that they can funcion as WLCs. 

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Just like Converged Access (CA) with the 3650/3850, Cisco is about to "kill" this feature.  Do not even consider it. 

NOTE:  Converged Access and embedded WLC (eWLC) are the same thing, i. e.  turning the switch into a WLC, and the name was re-branded, possibly, because CA left some really bad taste with a lot of people (and do not want to be reminded what a horrible train wreck a product it was).

[IanMurphy]

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@Leo Laohoo wrote:Sez who?  Is the WiFi being used at, say, 4am?  On a Saturday? 

I upgrade WLC firmware outside business hours.  I do not have to "be there".  I can schedule the WLC to reboot at a future time/date.  

When I said I had been unable to make the change, I meant that this is a multi-story building with a load of APs all connected to a single WLC and most of the APs are in rooms used for events, which can run any time from 8am to 10pm. This week just happens to have been an busy week, making daytime changes impossible and I didn't feel like staying up to make make remote changes. Last night I was able to connect and make the change remotely.

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Just like Converged Access (CA) with the 3650/3850, Cisco is about to "kill" this feature.  Do not even consider it. 

NOTE:  Converged Access and embedded WLC (eWLC) are the same thing, i. e.  turning the switch into a WLC, and the names were changed, possibly, because CA left some really bad taste to a lot of people.  

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This is what I was hoping to find out. It did seem like an odd thing to implement in the first place, though interesting as an idea. 

Thanks very much for the info.

[Rich R · Accepted solution]

The 2504 can run up to 8.5 which will also support the 1602 APs: https://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-controller-software/200046-tac-recommended-aireos.html#anc10

If you want to upgrade to 8.5 you might need to do it in a few steps to get to 8.5 - read all the release notes carefully.

I'd suggest first to 8.0.152.0 https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn80mr5.html#pgfId-1162364 table 6

and then 8.5.182.0 https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn85mr8.html#software-rel-types-and-recommendations_85mr8 table 2

Check newer AP compatibility: https://www.cisco.com/c/en/us/td/docs/wireless/compatibility/matrix/compatibility-matrix.html#ctr-ap_support

Running EWC (standalone) on the Cat 9000 switches was rather brief - Cisco end of life'd it last year so don't go there: https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9800-series-wireless-controllers/guide-c07-744299.html

But there are some alternatives suggested there.