Wireless Access

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Occasional Contributor II
Posts: 11
Registered: ‎04-13-2009

Poor RSSI and throughput between 2 IAP-175 mesh

Hi All,

I've a customer setup a mesh link between 2 IAP-175 which are about 400 meters apart with clear LOS. Both IAPs are attached with an Ant 2x2 5614-U external antenna.

 

However we noticed that LED indictors on both did not go beyond 2 bars and the RSSI value always hovers around 35 ~ 40 dbm only. We ran an iperf throughput tests with a laptop connected to mesh point and mesh portal at the other end. The results showed that from the radios stats, the packets are transmitting at around 270Mbps and receiving at 300Mbps which is reasonable, however the channel utilisation is hitting only 39% and the throughput is only 80Mbps. This is very far off from the thoretical max of 150Mbps.

 

Primary-Point# show ap mesh ni eighbours

Neighbor list
-------------
MAC                Portal  Channel  Age  Hops  Cost  Relation          Flags  RSSI  Rate Tx/Rx  A-Req  A-Resp  A-Fail  HT-Details       Cluster ID
---                ------  -------  ---  ----  ----  --------          -----  ----  ----------  -----  ------  ------  ----------       ----------
xxxxxxxxxx  Yes     149+     0    0     4.00  P 5d:15h:41m:23s  HLK    39    300/300     1      1       0       HT-40MHzsgi-2ss  194c96b88cb7586fe383f80f89d96cc

Total count: 1, Children: 0

 

Tx HT 216 Mbps                 72720
Tx HT 240 Mbps                 281628
Tx HT 243 Mbps                 500425
Tx HT 270 Mbps                 37120968  <<<<<<<<<<<<<

 

Rx HT 240 Mbps    1215691
Rx HT 243 Mbps    371076
Rx HT 270 Mbps    82574913
Rx HT 300 Mbps    3144872160  <<<<<<<<<<<<

 

Channel Busy 1s                39   <<<<<<<<<<<<<<<<
Channel Busy 4s                43
Channel Busy 64s               39
Ch Busy perct @ beacon intvl   44 42 43 44 44 42 42 44 45 19 25 46 41 45 42 43 45 43 45 44 45 43 42 46 45 42 46 42 47 43
Rx Time perct @ beacon intvl   36 33 35 36 35 35 34 36 36 16 20 38 33 37 34 34 35 35 37 35 34 35 34 36 35 33 37 34 38 34

 

The iperf parameters we used at both sides are as follows :

 

Iperf –c 1.2.3.4   -w 512k  -t 60   -P 4

Iperf –s  -w 512k

 

Initially I suspect that there's some problem with the wifi NIC of the clients or some bottlenecks along the network path. But we did the same test with both same clients on the wired network and they are able to achieve > 900Mbps thoughput. So there should not be any issue with the machines.

 

Please advice how we can bump up the channel utilisation and throughput.

 

Thanks

 

Occasional Contributor II
Posts: 11
Registered: ‎04-13-2009

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Hi All,

 

Any advice is much appreciated.

 

 

Thanks! :manembarrassed:

MVP
Posts: 4,266
Registered: ‎07-20-2011

Re: Poor RSSI and throughput between 2 IAP-175 mesh

 

What type of wireless nic are you using ? 3x3:3 or 2x2:2 ?

 

Depending on the type of nic you are using it will determine speeds you can obtain too, also remember that you will be using 802.11gn (20 Mhz) for client traffic when meshing .

 

Why are you trying to accomplish by increasing the utilization on that channel ? 

 

Can you please share the show ap mesh topology ?

 

 

 

 

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Occasional Contributor II
Posts: 11
Registered: ‎04-13-2009

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Hi Fabian,

 

Thanks for the reply. I do not have the "show ap mesh topo" output. What i have are only the "show ap mesh neighbour" and "show ap mesh link:

 

Primary-Portal# show ap mesh link

Neighbor list
-------------
MAC                Portal             Channel  Age  Hops  Cost  Relation         Flags  RSSI  Rate Tx/Rx  A-Req  A-Resp  A-Fail  HT-Details       Cluster ID
---                ------             -------  ---  ----  ----  --------         -----  ----  ----------  -----  ------  ------  ----------       ----------
x:x:x:x  x:x:x:x  149+     0    1     7.00  C 5d:15h:38m:4s  HLK    37    300/300     1      1       0       HT-40MHzsgi-2ss  194c96b88cb7586fe383f80f89d96cc

Total count: 1, Children: 1
Relation: P = Parent; C = Child; N = Neighbor; B = Blacklisted-neighbor
Flags: R = Recovery-mode; S = Sub-threshold link; D = Reselection backoff; F = Auth-failure; H = High Throughput; L = Legacy allowed
 K = Connected; U = Upgrading; G = Descendant-upgrading; Z = Config pending; Y = Assoc-resp/Auth pending
 a = SAE Accepted; b = SAE Blacklisted-neighbour; e = SAE Enabled; u = portal-unreachable; o = opensystem

Primary-Portal# show ap mesh neighbours

Neighbor list
-------------
MAC                Portal             Channel  Age  Hops  Cost  Relation          Flags  RSSI  Rate Tx/Rx  A-Req  A-Resp  A-Fail  HT-Details       Cluster ID
---                ------             -------  ---  ----  ----  --------          -----  ----  ----------  -----  ------  ------  ----------       ----------
x:x:x:x  x:x:x:x  149+     0    1     7.00  C 5d:15h:37m:45s  HLK    38    300/300     1      1       0       HT-40MHzsgi-2ss  194c96b88cb7586fe383f80f89d96cc

Total count: 1, Children: 1
Relation: P = Parent; C = Child; N = Neighbor; B = Blacklisted-neighbor
Flags: R = Recovery-mode; S = Sub-threshold link; D = Reselection backoff; F = Auth-failure; H = High Throughput; L = Legacy allowed
 K = Connected; U = Upgrading; G = Descendant-upgrading; Z = Config pending; Y = Assoc-resp/Auth pending
 a = SAE Accepted; b = SAE Blacklisted-neighbour; e = SAE Enabled; u = portal-unreachable; o = opensystem

 

But as you can see above, the mesh link is using 40Mhz channels. How can I know whether the wireless nic is using 2x2 or 3x3? Any CLI command to show that?

 

Thanks

MVP
Posts: 4,266
Registered: ‎07-20-2011

Re: Poor RSSI and throughput between 2 IAP-175 mesh

The link between the mesh portal and mesh point is using a 40 MHz on 802.11an but when a device connects it will use 802.11bgn.

Are using a windows or a Mac device?
Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Occasional Contributor II
Posts: 11
Registered: ‎04-13-2009

Re: Poor RSSI and throughput between 2 IAP-175 mesh

We are using both windows laptops to perform the iperf test.

Guru Elite
Posts: 20,970
Registered: ‎03-29-2007

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Wolfie99,

 

That is at 400 Meters?  Those are great numbers.  The channel is 39% busy which would definitely limit your throughput.

 

What do you think it should be?

 



Colin Joseph
Aruba Customer Engineering

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

Occasional Contributor II
Posts: 11
Registered: ‎04-13-2009

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Hi Joseph,

Thanks for the reply. But I thought the 39% channel busyness was due to the packets traversing the link when I'm performing the iperf test?

I've actually checked with one of your local TAC and he informed me that he managed to achieve a throughput of 140+ Mbps with a channel util rate of 80+% in a lab environment.

 

Is it possible to achieve that rate at a distance of 400m apart for the IAPs? or is it a limitation?

 

 

Thanks and Regards,

 

Guru Elite
Posts: 20,970
Registered: ‎03-29-2007

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Wolfi99,

 

Please go with TAC's recommendation, because they have more detailed information about your issue.  As distance increases, the chance that you will get the theoretical maximum decreases.  You should not expect to get the theoretical maxiumum at 400 meters.

 



Colin Joseph
Aruba Customer Engineering

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

Occasional Contributor II
Posts: 11
Registered: ‎04-13-2009

Re: Poor RSSI and throughput between 2 IAP-175 mesh

ok. Noted. Thanks for the advice. In your opinion, what is a reasonable range for the throughput?

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