Wireless Access

Has anyone experienced higher latencies with 802.11ac as well?

I have an Acer laptop with a Broadcom BCM43225 chipset and a Lenovo T440s with a Intel Dual Band Wireless-AC 7260 chipset.

Both laptops run Windows 7 x64. The Acer uses an old driver version from March 22, 2010 and the Lenovo is using the latest driver from August 1, 2013.

Both laptops are connected to the same Aruba AP-225 and to the same SSID. Both are pinging their default gateway and I have sent 2000 ICMP echo requests on each laptop.

The Acer laptop reports an average round trip time of 6ms, the Lenovo 43ms. The Lenovo also reports three digit round trip times occasionally.

I have not fiddled around with any of the 802.11ac settings on the Aruba controller side yet since I don't know if it would make matters worse or not.

Here is the status message on the Lenovo for the WiFi connection:

What are you pinging ? something internal or out to the internet ?

You should look at a couple of things :

- The health of your RF environment , show ap arm history ap-name <apname> and show ap arm rf-summary ap-name <apname> this would allow to see some of that information

- Make sure that there isnt any packet loss from the AP to the controller 

- Have you tried running a perf test from the AP or controller :

(controller) #perf-test server start ap ap-name <apname> and download iPerf or jPerf and see what's the throughput your are getting from your wireless device

I am pinging the default gateway for this particular SSID which is internal.

I ran a perf-test from the controller to the AP where both clients are connected to:

(aruba-wlc3) #show perf-test reports ap ap-name M7A-1OG-AP02

Perf-test: Success

Dec 2 15:02:41 2013
jxu: interval 0, 1.000000
------------------------------------------------------------
Client connecting to 172.22.2.10, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 172.20.89.141 port 53985 connected with 172.22.2.10 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 1.0 sec 2.12 MBytes 17.8 Mbits/sec
[ 3] 1.0- 2.0 sec 2.25 MBytes 18.9 Mbits/sec
[ 3] 2.0- 3.0 sec 2.25 MBytes 18.9 Mbits/sec
[ 3] 3.0- 4.0 sec 2.25 MBytes 18.9 Mbits/sec
[ 3] 4.0- 5.0 sec 2.12 MBytes 17.8 Mbits/sec
[ 3] 5.0- 6.0 sec 2.25 MBytes 18.9 Mbits/sec
[ 3] 6.0- 7.0 sec 2.25 MBytes 18.9 Mbits/sec
[ 3] 7.0- 8.0 sec 2.12 MBytes 17.8 Mbits/sec
[ 3] 8.0- 9.0 sec 2.25 MBytes 18.9 Mbits/sec
[ 3] 9.0-10.0 sec 2.25 MBytes 18.9 Mbits/sec
[ 3] 0.0-10.1 sec 22.2 MBytes 18.6 Mbits/sec

As for the health of the RF environment, here are the results of the 'show ap arm' commands:

(aruba-wlc3) #show ap arm history ap-name M7A-1OG-AP02

Interface :wifi0
ARM History
-----------
Time of Change Old Channel New Channel Old Power New Power Reason
-------------- ----------- ----------- --------- --------- ------
2013-12-02 15:05:03 36E 36E 9 12 P+
2013-12-02 14:18:05 36E 36E 12 9 P-
2013-12-02 06:31:55 36E 36E 15 12 P-
2013-11-29 23:50:45 36E 36E 18 15 P-
2013-11-29 23:45:11 36E 36E 24 18 P-
2013-11-27 01:59:24 36E 36E 21 24 P+
2013-11-27 01:54:59 36E 36E 18 21 P+
2013-11-27 01:50:24 36E 36E 24 18 P-
2013-11-25 16:55:33 36E 36E 21 24 P+
2013-11-25 16:43:53 36E 36E 18 21 P+
2013-11-25 11:05:54 36E 36E 24 18 P-
2013-11-24 13:20:53 36E 36E 21 24 P+
2013-11-24 12:40:29 36E 36E 24 21 P-
2013-11-23 11:24:23 36E 36E 21 24 P+
2013-11-23 11:13:26 36E 36E 24 21 P-
2013-11-22 17:01:46 36E 36E 21 24 P+
2013-11-22 16:56:56 36E 36E 18 21 P+
2013-11-22 16:52:01 36E 36E 15 18 P+
2013-11-22 12:21:51 36E 36E 12 15 P+
2013-11-22 10:25:59 36E 36E 9 12 P+
2013-11-22 10:18:17 36E 36E 15 9 P-
2013-11-22 09:53:46 36E 36E 12 15 P+
2013-11-22 09:31:24 36E 36E 18 12 P-
2013-11-22 09:10:47 36E 36E 24 18 P-
2013-11-21 18:28:44 36E 36E 21 24 P+
2013-11-21 18:22:24 36E 36E 18 21 P+
2013-11-21 15:35:31 36E 36E 24 18 P-
2013-11-21 14:03:40 36E 36E 21 24 P+
2013-11-21 13:33:23 36E 36E 24 21 P-
2013-11-21 12:39:40 36E 36E 21 24 P+
2013-11-21 11:15:40 36E 36E 18 21 P+
2013-11-21 10:43:10 36E 36E 15 18 P+
Interface :wifi1
ARM History
-----------
Time of Change Old Channel New Channel Old Power New Power Reason
-------------- ----------- ----------- --------- --------- ------
2013-12-02 14:51:46 1 1 12 9 P-
2013-12-02 14:44:48 1 1 9 12 P+
2013-12-02 13:31:27 1 1 12 9 P-
2013-12-02 13:25:59 1 1 9 12 P+
2013-12-02 13:21:00 1 1 12 9 P-
2013-12-02 13:16:41 1 1 9 12 P+
2013-12-02 13:09:46 1 1 12 9 P-
2013-12-02 13:01:48 1 1 9 12 P+
2013-12-02 12:33:02 1 1 12 9 P-
2013-12-02 12:27:24 1 1 9 12 P+
2013-12-02 12:07:17 1 1 12 9 P-
2013-12-02 12:01:37 1 1 9 12 P+
2013-12-02 11:17:47 1 1 12 9 P-
2013-12-02 11:11:31 1 1 9 12 P+
2013-12-02 09:52:36 1 1 12 9 P-
2013-12-02 09:45:14 1 1 9 12 P+
2013-12-02 09:09:36 1 1 12 9 P-
2013-12-02 09:02:53 1 1 9 12 P+
2013-12-02 07:31:06 1 1 12 9 P-
2013-12-02 07:25:04 1 1 18 12 P-
2013-12-02 06:49:10 1 1 15 18 P+
2013-12-02 06:28:37 1 1 12 15 P+
2013-12-02 05:51:26 1 1 9 12 P+
2013-12-02 05:38:12 1 1 12 9 P-
2013-12-02 05:26:42 1 1 9 12 P+
2013-12-02 05:21:26 1 1 12 9 P-
2013-12-02 05:01:33 1 1 9 12 P+
2013-12-02 04:02:15 1 1 12 9 P-
2013-12-02 03:57:43 1 1 9 12 P+
2013-12-02 03:40:26 1 1 15 9 P-
2013-12-02 03:32:22 1 1 12 15 P+
2013-12-02 03:27:54 1 1 9 12 P+
I: Interference, R: Radar detection, N: Noise exceeded, Q: Bad Channel Quality E: Error threshold exceeded, INV: Invalid Channel, G: Rogue AP Containment, M: Empty Channel, P+: Increase Power, P-: Decrease Power, 40INT: 40MHZ intol detected on 2.4G, NO40INT: 40MHz intol cleared on 2.4G, OFF: Turn off Radio, ON: Turn on Radio

(aruba-wlc3) #show ap arm rf-summary ap-name M7A-1OG-AP02

Channel Summary
---------------
channel retry phy-err mac-err noise util(Qual) cov-idx(Total) intf_idx(Total)
------- ----- ------- ------- ----- ---------- -------------- ---------------
36 17 0 0 95 12/5/7/0/100 13/0(13) 6/0//4/1(11)
40 0 0 0 95 3/2/1/0/100 0/0(0) 7/0//0/4(11)
44 28 0 0 95 3/2/1/0/72 8/0(8) 0/2//5/2(9)
48 0 0 0 95 3/2/1/0/89 8/0(8) 0/0//3/5(8)
52 0 0 0 95 3/2/1/0/100 0/0(0) 0/0//9/1(10)
56 0 0 0 93 4/3/1/0/100 0/0(0) 0/0//0/10(10)
60 0 0 0 93 3/3/1/0/100 0/0(0) 0/0//20/0(20)
64 0 0 0 93 3/2/1/0/100 0/0(0) 0/0//0/7(7)
100 0 0 0 93 5/3/1/0/99 5/0(5) 27/0//7/0(34)
104 0 0 0 93 3/2/1/0/100 0/0(0) 0/0//0/10(10)
108 0 0 0 93 3/2/1/0/100 5/5(10) 0/0//25/0(25)
112 0 0 0 93 8/3/1/0/96 0/0(0) 0/0//0/17(17)
116 0 0 0 93 3/2/1/0/100 0/6(6) 0/0//32/0(32)
120 0 0 0 93 3/2/1/0/100 0/0(0) 0/0//0/9(9)
124 0 0 0 93 4/3/1/0/100 0/0(0) 0/0//0/0(0)
128 0 0 0 93 3/2/1/0/100 0/0(0) 0/0//0/0(0)
132 0 0 0 93 3/2/1/0/100 0/0(0) 0/0//0/0(0)
136 0 0 0 93 4/3/1/0/100 0/0(0) 0/0//0/0(0)
140 0 0 0 93 3/2/1/0/100 0/0(0) 0/0//0/0(0)
1 0 0 0 93 28/16/12/0/23 10/0(10) 87/19//0/0(106)
6 0 0 0 95 27/14/11/0/98 11/0(11) 59/23//0/0(82)
11 0 0 0 96 27/16/11/0/100 0/0(0) 0/10//0/0(10)

Columns:util(Qual): ch-util/rx/tx/ext-ch-util/quality

HT Channel Summary
------------------
channel_pair Pairwise_intf_index
------------ -------------------
116-120 41
52-56 20
100-104 44
124-128 0
36-40 22
60-64 27
108-112 42
132-136 0
44-48 17

VHT Channel Summary
-------------------
channel_group 80MHz_intf_index
------------- ----------------
116-128 41
52-64 47
100-112 86
36-48 39

Interface Name :wifi0
Current ARM Assignment :36E/12
Covered channels a/g :6/0
Free channels a/g :10/0
ARM Edge State :disable
Last check channel/pwr :4m:44s/2m:5s
Last change channel/pwr :53m:36s/2m:5s
Next Check channel/pwr :2m:37s/4m:25s
Assignment Mode :Single Band

Interface Name :wifi1
Current ARM Assignment :1/9
Covered channels a/g :0/2
Free channels a/g :0/1
ARM Edge State :disable
Last check channel/pwr :1m:17s/1m:55s
Last change channel/pwr :6h:21m:58s/15m:15s
Next Check channel/pwr :6m:26s/6m:2s
Assignment Mode :Single Band

I connected a PC running Ubuntu on a wired LAN port to the same VLAN as the wireless clients and set up an iPerf server on it.

Then I ran an iPerf test from the 802.11n Acer laptop and from the 802.11ac Lenovo laptop. Results in Green are from the Acer, results in Red are from the Lenovo:

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 0.25 MByte (WARNING: requested 0.25 MByte)
------------------------------------------------------------
[ 4] local 10.100.132.137 port 5001 connected with 10.100.133.45 port 3183
[ ID] Interval Transfer Bandwidth
[ 4] 0.0- 5.0 sec 31.4 MBytes 52.6 Mbits/sec
[ 4] 5.0-10.0 sec 30.1 MBytes 50.6 Mbits/sec
[ 4] 10.0-15.0 sec 29.8 MBytes 50.0 Mbits/sec
[ 4] 15.0-20.0 sec 30.0 MBytes 50.4 Mbits/sec
[ 4] 20.0-25.0 sec 33.1 MBytes 55.5 Mbits/sec
[ 4] 25.0-30.0 sec 27.8 MBytes 46.7 Mbits/sec
[ 4] 30.0-35.0 sec 31.1 MBytes 52.1 Mbits/sec
[ 4] 35.0-40.0 sec 32.3 MBytes 54.1 Mbits/sec
[ 4] 40.0-45.0 sec 33.0 MBytes 55.3 Mbits/sec
[ 4] 45.0-50.0 sec 31.9 MBytes 53.4 Mbits/sec
[ 4] 50.0-55.0 sec 32.2 MBytes 54.1 Mbits/sec
[ 4] 55.0-60.0 sec 31.4 MBytes 52.6 Mbits/sec
[ 4] 0.0-60.1 sec 374 MBytes 52.3 Mbits/sec
[ 5] local 10.100.132.137 port 5001 connected with 10.100.132.33 port 49574
[ 5] 0.0- 5.0 sec 7.36 MBytes 12.4 Mbits/sec
[ 5] 5.0-10.0 sec 8.34 MBytes 14.0 Mbits/sec
[ 5] 10.0-15.0 sec 10.2 MBytes 17.1 Mbits/sec
[ 5] 15.0-20.0 sec 9.03 MBytes 15.2 Mbits/sec
[ 5] 20.0-25.0 sec 10.8 MBytes 18.1 Mbits/sec
[ 5] 25.0-30.0 sec 11.3 MBytes 19.0 Mbits/sec
[ 5] 30.0-35.0 sec 8.54 MBytes 14.3 Mbits/sec
[ 5] 35.0-40.0 sec 8.41 MBytes 14.1 Mbits/sec
[ 5] 40.0-45.0 sec 9.66 MBytes 16.2 Mbits/sec
[ 5] 45.0-50.0 sec 9.31 MBytes 15.6 Mbits/sec
[ 5] 50.0-55.0 sec 10.2 MBytes 17.1 Mbits/sec
[ 5] 55.0-60.0 sec 8.55 MBytes 14.3 Mbits/sec
[ 5] 0.0-60.2 sec 112 MBytes 15.6 Mbits/sec

To be fair:

- 802.11ac is very new  -  Manufacturers are still tuning their 802.11ac client drivers so performance will be variable, but higher than 802.11n

- How clients perform in a closed single-client testing setting can be very different than when any other clients or devices are introduced

- Having a client looking at Wifi statistics like Inssider running or open while doing performance testing can introduce scans, which will degrade performance

There are many more things you can check to ensure performance.  I would open a TAC case so that they can run all of them down with you, instead of me blindly pasting suggestions in here.

Thanks for all your suggestions! I find this community very useful and always learn something new. Didn't know there is a built-in iPerf within ArubaOS! :-)

I also tried a few things this morning to narrow down the problem...

First I rebooted the master and the standby controller. I made some changes to the IP configuration last week and until this morning I did not perform the recommended reboot.

Also, I walked to another building on our campus where we ONLY have AP225's installed to see if I also experience the problem there as well. No, throughput was good on the Lenovo 802.11ac Laptop. Almost 100 Megabits per second with iPerf!

Then I realized that I am running a mixed AP Group configuration here in the building where my office is.

Meaning that I have AP225 as well as AP135 in the same AP Group because the building isn't fully migrated to 225's yet. So I configured separate AP Groups for the 225s and the 135s. Of couse when I moved the APs into a different group, the APs rebooted as well.

At the end the situation looked much better. Latency is down to 3 or 4ms and iPerf throughput is about 90MBits/s. I am not sure what helped to resolved this but for the moment I am fine with the situation. Considering that I have to run 6.3 ED code because I need AirGroup functionality... so I am not expecting 100% stability anyways.

I don't know if there is a recommendation from Aruba Networks when it comes to having different AP types within the same AP Group?

Have you done a speedtest to see if the throughput is also bad?  Try doing a ping test separately, when no other devices are on the WLAN for an accurate baseline?  Pings will go up and down due to latency/congestion.  Please try to isolate the client under test to determine if the ping AND the throughput are not better than regular 802.11n clients.