I responded to Dominic's email directly, then I saw this one. Answers inline below.
Jason Boyers - CCIE #26024 (Wireless) Technical Instructor - IPexpert [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Stalder Dominic Sent: Wednesday, February 09, 2011 2:48 AM To: Kristján Ólafur E›var›sson; [email protected] Subject: Re: [CCIE Wireless] 1. Two questions about QoS (Stalder Dominic) Hi Kristjan and Jason Thanks for your answers, but what I mean with "maximum" is not the absolute maximum of what the 802.1p value can be, but it maximizes the 802.11e UP value from the client to this value. Let's say the value is set to 6 on the controller and the clients sends a packet with 802.11e UP = 6, then the controller will not change the value and will map this 802.11e UP value 6 to the AVVID IP DSCP value of 46 (EF), as you see in the link you sent: http://www.cisco.com/en/US/tech/tk722/tk809/technologies_configuration_examp le09186a00807e9717.shtml#intro But if the controller has set the 802.1p value to 0 and the same client sends a packet with 802.11e UP = 6 again, this value will be cut down to 0 and will then be mapped to the AVVID IP DSCP value of 0 (Best Effort). This is what I tried to say with "maximum" ;-) *** The 802.1p value in the QoS profile determines the maximum CoS value for the WLC connection (upstream and downstream.) The QoS Profile itself (Platinum, Gold, etc.) sets the maximum 802.11e UP value. So, if the QoS Profile is Platinum, and a WMM client sends 802.11e UP 4, that will get mapped to AF31, because it is below the maximum (and this is presuming that ACM is not enabled for the Video AC.) On the wired connection, if the 802.1p value in the QP is set to “6,” and the incoming LWAPP packet has a DSCP of AF31, it will get mapped to CoS 3 (and DSCP CS3.) If it is coming from the wired client, and the CoS value is 3, it will get mapped to CoS 3 and DSCP CS3 on the LWAPP side. *** For non-WMM clients, based on my testing, the inbound (upstream) traffic is placed into the default queue for the AP. This gets mapped to DSCP 0, no matter what QP is used. I have done a little bit of initial testing with a 7920G phone to see if there is something else that it does, but have not found any difference thus far. As far as downstream traffic, it works the same as for WMM clients (incoming CoS to WLC gets mapped to outgoing CoS and DSCP up to max). Then, when it gets to the AP, it does not get an 802.11e marking as it could not understand that marking anyways. For the second question, I found some information in Jeromes Youtube video, starting at about 4 minutes 20 seconds: http://www.youtube.com/user/cciewireless#p/u/8/1gbbAFdsQdQ There he explain, that you can not enable "7920 Client CAC" (QBSSv1) togheter with "WMM Policy" (QBSSv2). But when you enable "7920 AP CAC", this seems also to be somewhat of QBSSv2. You can find the wireshark captures there, maybe you can interpret this better than me? Somehow confusing for me. *** What Jerome is explaining is that there is optionally a standard QBSS Load Element Information Element that is in the beacon, as well as optionally a CCX QBSS Load Information IE in the beacon. For the standard QBSS, there is either the v1, Cisco Proprietary Load IE, which the 7920 can understand and use to make joining and roaming decisions. That is 7920 Client CAC. In that same place in the frame, there can also be QBSS v2, which is the 802.11e standard CAC. When WMM is allowed or required, that IE is automatically created. Since that IE cannot have both v1 and v2, that is why you can’t select both WMM Allowed/Required and 7920 Client CAC. Cisco can add proprietary CCX IEs, and one of those is a QBSS IE. Since the 7920 is not a WMM client, it cannot understand the standard QBSS v2 IE. However, because it is a CCX client, it can understand the CCX IE (if it is at v1.3(3), I believe.) So, as you saw in the video, you cannot have both WMM Allowed/Required and the 7920 Client CAC in the same SSID, as we stated above. However, because each SSID sends out its own beacons, different SSIDs CAN have different settings. So, one SSID could have WMM Disabled with 7920 Client CAC, while another can be WMM Required (WMM Required with 7920 AP CAC would be allowed, but 7920s wouldn’t be able to connect.) Regards Dominic > Von: Kristján Ólafur E›var›sson <[email protected]> > Datum: Wed, 9 Feb 2011 00:02:28 +0000 > An: "[email protected]" <[email protected]> > Cc: Dominic Stalder <[email protected]> > Betreff: 1. Two questions about QoS (Stalder Dominic) > > Let me try this one Dominic. > > 1. I would say that zero is no the maximum value. I gather you want the higest > "value" that a packet > can have. For the QOS mapping table 802.1p 0 would be DSCP 0, or Best effort. > So Max would be 7 (lwapp control) or 6 (voice platinum) > Here is a very good reference on the QOS table mappings in wireless: > http://www.cisco.com/en/US/tech/tk722/tk809/technologies_configuration_example > 09186a00807e9717.shtml#intro > > BUT if you look at the help in the WLC gui just below the value. it says: * > the value 0 (zero) indicates that the feature is disabled. > So putting it to zero would not mark anything! right ? > > What I don´t understand, and would like to get some feedback on is: If you > look at the table 802.1p values. 0 is marked is Best effort (WLC Silver) > but 1 and 2 values are there for "background" in 802.1p. 802.11e "Background" > is worse than Silver (right?), so I don´t understand why the table > claims 1 and 2 for Background and 0 for silver. Anyone ? > > Regarding the "What happens.." section of you question. When you set value of > 6 in the WLC. You actually get mapped > to value 5. So from what you chose you always auto mapped one lower AVVID > 802.1p value. So in WLC use 6 when you want AVVID 5. > There isn´t anything that explains it in the GUI you just have to know. So i > guess, even though the value input is for 802.1p in the WLC, you > want to think from the 802.11e pespective. That is ask your self "what 802.11e > UP (user priority) value am I going to map from ?" That at least helps me... > This video with Jerome explains it preety > well.http://www.youtube.com/watch?v=5AHpIAEu3uQ&feature=related > > 2. I don´t have clue here. We better investigate. But I hope someone else > knows :D > > regards. Krisjan > > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 8 Feb 2011 08:59:43 +0000 > From: Stalder Dominic <[email protected]> > To: "[email protected]" > <[email protected]> > Subject: [CCIE Wireless] Two questions about QoS > Message-ID: <c976c48b.2e76%[email protected]> > Content-Type: text/plain; charset="us-ascii" > > Hi there > > I have two questions about QoS on the controllers: > > 1. If the 802.1p value under QoS profiles (for example Platinum) is set to 0, > will all LWAPP data pakets be marked with a DSCP value of 0. As I understand, > this is the maximum value, that a packet can have, if it falls within this > profile. > > But what happens, when I set the value to 6 (as recommended) and a WMM client > has a 802.11e UP value of 5. Will the LWAPP packet be forwarded with DSCP 5, I > think, or am I wrong? If it would be a non-WMM client, the value would be 6, > right? > > 2. Can QBSSv1 and QBSSv2 coexist? I think the can coexist on the controller, > but they CANNOT coexist within one WLAN. What would you say? > > Thanks and best regards > Dominic _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
