topic Buffering in wireless network in Wireless

Buffering in wireless network

ASF_SVI_ITE — Sun, 04 Jul 2021 06:09:16 GMT

Hi guys,

what about this topic? How can I limit the buffering on APs? Reducing packet retry value? Packet retry timeout? RTS retries? What else?

I thanks in advance for any suggestion

Re: Buffering in wireless network

Scott Fella — Mon, 03 Dec 2012 14:25:33 GMT

Eliminate any interference and co channel interference. Other than that, there really isn't much you can do. Wireless is half duplex so only one device can either transmit or receive.

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Re: Buffering in wireless network

George Stefanick — Mon, 03 Dec 2012 15:24:24 GMT

Scott is there a command you can set the rts size ?

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Re: Buffering in wireless network

Scott Fella — Mon, 03 Dec 2012 15:36:47 GMT

George.... I don't believe so unless its one of those hidden commands, but I doubt it. It would be so much work for TAC if this was configurable:)

Thanks,

Scott

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Re: Buffering in wireless network

ASF_SVI_ITE — Mon, 03 Dec 2012 15:42:04 GMT

Hi Scott, thanks for the suggestion. but are you sure that the parameters written above don't care to the problem?

Re: Buffering in wireless network

George Stefanick — Mon, 03 Dec 2012 15:42:26 GMT

Looks like you can but only for mesh aps ..

https://supportforums.cisco.com/thread/2001107

Never used it personally ..

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Re: Buffering in wireless network

ASF_SVI_ITE — Mon, 03 Dec 2012 15:47:44 GMT

George...in effect I have already seen the configuration note for this option....in the wgb realized by 1242AP usage, rts retries is set equal to 8, so lower enough. I' m asking if there is something to tune on the WLC (WiSM cards on 6500 Catalyst)?

Thanks

Re: Buffering in wireless network

Scott Fella — Mon, 03 Dec 2012 15:48:04 GMT

I really don't understand what you are saying. All I can say is that since wireless is half duplex, its like a hub network, every device it going wait for its turn to communicate. Interference is the biggest problem that causes retires along with multipath. Its a normal thing to see in wireless, but having a good site survey, knowing of the interferers and having a solid configuration, will help, but not eliminate any retries you will see.

Thanks,

Scott

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Re: Buffering in wireless network

ASF_SVI_ITE — Mon, 03 Dec 2012 15:54:57 GMT

Sorry Scott, I have tried to explain the problem but too speedly...losing details for example of the application and the existing wireless infrastructure. I agree with what you said about wifi, interference,etc....goods indications.

Let me add that I' m triyng to understand the behaviour of a mobile application or, in other words, how is the behavior in a metro environment where a WGB onboard has to connect with the wayside while it is moving

Buffering in wireless network

Scott Fella — Mon, 03 Dec 2012 16:08:23 GMT

Well now since your talking about outdoor mobile devices, that explains it. That is tough to design just depending on what your really trying to accomplish. I have done outdoor mesh in a truck yard so that these trucks can get information on what to pickup, where to park, etc. This however is just for a given area. I have also done ship yards where the boats prior to docking can connect up to the wireless until the ship has docked and they connect up the fiber. You will always get a lot of reties because of mobile units moving fast, some object blocking the signal, etc. I know that George has done some with mining companies so he can also put his 2¢. I don't think there is a way to increse or decres rts on a WLC.

Thanks,

Scott

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Buffering in wireless network

Saravanan Lakshmanan — Mon, 03 Dec 2012 17:25:34 GMT

Yes.

this enhancement request is still open.

http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCte53425

Re: Buffering in wireless network

George Stefanick — Wed, 05 Dec 2012 06:01:45 GMT

Hummm.. That command states its on the WLC, not the bridge. I must not be understanding ..

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Buffering in wireless network

Saravanan Lakshmanan — Wed, 05 Dec 2012 19:19:17 GMT

From which direction RTS is seen, RTS retry can happen either direction.

currently, only fragment threshold and tcp mss are configurable for each AP, no rts/cts config on unified. you may try to use the ios command to tweak rts/cts per radio however it is not guranteed that it works and certainly this config can't survive reboot.

It is recommended to only enable 802.11g (OFDM) data rates (e.g. > 12 Mbps) to prevent from engaging in CTS for 802.11g protection when using Coexistence.

Re: Buffering in wireless network

Saravanan Lakshmanan — Wed, 05 Dec 2012 19:20:25 GMT

It is recommended to only enable 802.11g (OFDM) data rates (e.g. > 12 Mbps) to prevent from engaging in CTS for 802.11g protection when using Coexistence.

Re: Buffering in wireless network

Saravanan Lakshmanan — Wed, 05 Dec 2012 19:28:16 GMT

Monitor > Access Points > 802.11b/g/n

check: on WLC check if you're hitting on RTS Failure Count - This counter increments when a CTS is not received in response to an RTS. If you don't see an issue then the issue is something else. i believe WLC has an default retry count but unsure about the value.

802.11 MAC Counters

Tx Fragment Count		Multicast Tx Frame Count
Tx Failed Count		Retry Count
Multiple Retry Count		Frame Duplicate Count
RTS Success Count		RTS Failure Count
ACK Failure Count		Rx Fragment Count
Multicast Rx Frame Count		FCS Error Count
Tx Frame Count		WEP Undecryptable Count