Thread: [Madwifi-devel] Traffic differentiation problem using WME
Status: Beta
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From: Chiang K. T. <arc...@ya...> - 2008-05-28 17:54:01
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Dear all, Has anyone experienced any problem with traffic differentiation using WME. I think I'm sufficiently confident that 802.11e is implemented on the hardware I'm using after carrying out some simple experiments, as I can observe different behaviours when different AC is used. Here is the test I carried out, with both machines using MadWifi driver on D-Link DWL-AG530 and DWL-G650 respectively. AP - - - - - - - STA Traffic sources (e.g. 4, one for each AC) are generated and sent from AP -> STA, with the packets TOS marked accordingly. The outcome is sort of as expected, with priorities given to the ACs accordingly. However as soon as I change the testbed slightly, by connecting a Node to AP using Ethernet and then generating the traffic sources from that Node, results are no longer the same. Node --------------- AP - - - - - - - STA No traffic differentiation can be observed (AC_BE was not used in this case). I'd be very grateful if one of you MadWifi experts can shed some light on how the driver is written such that different results are observed on the above two very similar scenarios. Any pointers will be appreciated too. Thank you in advance. Regards Chiang |
From: Benoit P. <ben...@fr...> - 2008-05-28 19:21:56
Attachments:
201-qos-80211e.diff
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Chiang Kang Tan a écrit : | Dear all, | Has anyone experienced any problem with traffic | differentiation using WME. I think I'm sufficiently confident that | 802.11e is implemented on the hardware I'm using after carrying out | some simple experiments, as I can observe different behaviours when | different AC is used. | Here is the test I carried out, with both machines using MadWifi driver on D-Link DWL-AG530 and DWL-G650 respectively. | AP - - - - - - - STA | | Traffic sources (e.g. 4, one for each AC) are generated and sent from | AP -> STA, with the packets TOS marked accordingly. The outcome is | sort of as expected, with priorities given to the ACs accordingly. | | However as soon as I change the testbed slightly, by connecting a | Node to AP using Ethernet and then generating the traffic sources from | that Node, results are no longer the same. | Node --------------- AP - - - - - - - STA | No traffic differentiation can be observed (AC_BE was not used in this case). | | I'd be very grateful if one of you MadWifi experts can shed some | light on how the driver is written such that different results are | observed on the above two very similar scenarios. Any pointers will be | appreciated too. Thank you in advance. | | Regards | | Chiang | | ------------------------------------------------------------------------- | This SF.net email is sponsored by: Microsoft | Defy all challenges. Microsoft(R) Visual Studio 2008. | http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ | _______________________________________________ | Madwifi-devel mailing list | Mad...@li... | https://lists.sourceforge.net/lists/listinfo/madwifi-devel | Are you using IP TOS? Which tool are you using for your tested? It would help to reproduce the behavior you are seeing. I have been using the attached patch in order to classify IP TOS to AC class. Regards, Benoit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD4DBQFIPbC7OR6EySwP7oIRAq4pAJj2Edgmr5FaCh+qn7vLp8EFIUMLAKDigj6d mMuOP0A6ZXQ+SmP6Y3aY3w== =eu7G -----END PGP SIGNATURE----- |
From: Dennis E. <emb...@ho...> - 2008-05-30 16:45:58
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Bruno, > if there is only one high priority stream we will also start dropping high > priority packets. this is not ideal, >but i don't have a better solution at the moment. I think this situation begs for admission control. You really can't make any QoS guarantees without it, as this example illustrates. Dennis |