08-19-2009 05:04 AM
According to product bulletin no 3209 for the Cisco 4400 series, the Access Point supports 802.11e WMM.
My question goes to DSCP mapping, according to IEEE and your bulletin the DSCP field in the IP header should be set to 46 (10110 00) for mapping to a 802.11 QoS voice priority 6/7.
But my Wireshark trace revealed 4400N is mapping toward with 802.11 QoS is set to Priority 5 Video.
If I google DSCP mapping toward 802.11 QoS all IEEE documention I found says EF /Voice should have 46 or 101xxx in the DSCP IP field but running through Cisco and HP docs gives 46 or 48 as value, that is the correct value....
Regards Karl Henrik Nielsen
Added Wireshark packet from 4400N AP.
o. Time Source Destination Protocol
Info
5817 25.523410 192.168.0.1 192.168.0.4 RTP
PT=ITU-T G.711 PCMA, SSRC=0x505BE4FD, Seq=25853, Time=0
Frame 5817 (168 bytes on wire, 168 bytes captured) Radiotap Header v0,
Length 14 IEEE 802.11 QoS Data, Flags: ......F.
Type/Subtype: QoS Data (0x28)
Frame Control: 0x0288 (Normal)
Duration: 44
Destination address: ThraneTh_01:d2:39 (00:11:cf:01:d2:39)
BSS Id: Cisco-Li_d7:dc:f6 (00:23:69:d7:dc:f6)
Source address: ThraneTh_00:f4:be (00:11:cf:00:f4:be)
Fragment number: 0
Sequence number: 0
QoS Control
Priority: 5 (Video) (Video)
...0 .... = EOSP: Service period
Ack Policy: Normal Ack (0x00)
Payload Type: MSDU
QAP PS Buffer State: 0x0
Logical-Link Control
Internet Protocol, Src: 192.168.0.1 (192.168.0.1), Dst: 192.168.0.4
(192.168.0.4)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0xb8 (DSCP 0x2e: Expedited Forwarding; ECN: 0x00)
1011 10.. = Differentiated Services Codepoint: Expedited Forwarding (0x2e)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 120
Identification: 0x03c8 (968)
Flags: 0x00
Fragment offset: 0
Time to live: 64
Protocol: UDP (0x11)
Header checksum: 0xf49f [correct]
Source: 192.168.0.1 (192.168.0.1)
Destination: 192.168.0.4 (192.168.0.4) User Datagram Protocol, Src
Port: 1027 (1027), Dst Port: connected
(16384)
Real-Time Transport Protocol
08-19-2009 01:11 PM
Hi Karl,
This is the incorrect doc: http://www.cisco.com/en/US/prod/collateral/wireless/ps6302/ps8322/ps6366/prod_bulletin0900aecd80394844_ps6108_Products_Bulletin.html
I don't think this info is in the WAP4400N admin guide so here it is:
The WAP4400N supports 802.1p to WMM Mapping:
Wireless Queue CoS Access Category
Q1 7,6 WMM Voice Priority
Q2 5,4 WMM Video Priority
Q3 0,3 WMM Best Effort Priority
Q4 2,1 WMM Background Priority
Thanks,
Cindy Toy
Cisco Small Business
Support Community Manager
08-19-2009 11:30 PM
Thanks, but my real question was:
Which DSCP values maps to Q1 through Q4, in the IEEE documentation DSCP value 46 should map to Q1 but I proved above the 4400N maps to Q2.
08-20-2009 08:23 PM
Hi Karl,
The WAP4400N supports layer-2 prioritization. For DSCP you'll need to check your layer-3 device to see how the queues are mapped.
Here's an example:
802.1p Class of Service From DSCP Range
0 0-7
1 8-15
2 16-23
3 24-31
4 32-39
5 40-47
6 48-55
7 56-63
Based on this mapping a DSCP value of 46 would map to 5 and corresponds to the WMM Video Priority queue.
Regards,
Cindy
08-24-2009 01:34 AM
Thanks for your answer, and I was aware of 802.1p and 802.1Q header, but the Ethernet frame the 4400N receives, as you can see in my previous entry, does not have a 802.1Q field only the DSCP field is set and the 4400N is mapping into QoS for the 801.11 header. So the 4400N must have some mapping included based on the DSCP field. I have experimented on changing only the DSCP field and the mapping from the 4400N changes.
Regards Karl Henrik
09-06-2011 11:58 PM
Hey Karl,
Not sure if you found an answer to this, but if you check out the voice design guide, it does cover the mappings quite well.
http://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/vowlan/41dg/vowlan_ch2.html#wp1046226
Cheers,
Dan
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