en:developers:documentation:mac80211:queues
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| + | For QoS/WMM (EDCA) a mac80211 driver needs to have at least four queues. mac80211 will then program the queues according to the advertised access parameters. | ||
| + | |||
| + | **Legend:** | ||
| + | * **MQ**: mac80211 queue | ||
| + | * **AC**: Access Class | ||
| + | * **ACI**: Access Class Index | ||
| + | |||
| + | mac80211 queue mapping: | ||
| + | |**AC** |**MQ** | | ||
| + | |BK |3 | | ||
| + | |BE |2 | | ||
| + | |VI |1 | | ||
| + | |VO |0 | | ||
| + | |||
| + | 802.11 uses the following number scheme (cf. Table 7-36) | ||
| + | |**AC** |**ACI** | | ||
| + | |BK |01 (1) | | ||
| + | |BE |00 (0) | | ||
| + | |VI |10 (2) | | ||
| + | |VO |11 (3) | | ||
| + | |||
| + | Therefore, we have: | ||
| + | |AC |ACI |MQ | | ||
| + | |BK |1 |3 | | ||
| + | |BE |0 |2 | | ||
| + | |VI |2 |1 | | ||
| + | |VO |3 |0 | | ||
| + | |||
| + | Due to internal collisions (we don't really know what this means either) the queue numbering is important, and queue 0 is highest priority, 3 lowest. If your hardware has a different idea of queue priority, you may need to rewrite the queue number, but make sure to do it everywhere mac80211 passes a queue number (conf_tx, skb_get_queue_mapping). | ||
| + | |||
| + | The user priority is used as follows (802.11-2007 table 9-1): | ||
| + | |**UP** |**AC** |**Priority** | | ||
| + | |1 |BK |Lowest | | ||
| + | |2 |BK |. | | ||
| + | |0 |BE |. | | ||
| + | |3 |BE |. | | ||
| + | |4 |VI |. | | ||
| + | |5 |VI |. | | ||
| + | |6 |VO |. | | ||
| + | |7 |VO |Highest | | ||
| + | |||
| + | **TOS:** | ||
| + | |||
| + | mac80211 currently determines the UP based only on the IPv4 TOS field, unless the packet priority is set to 256..263 with setsockopt(SO_PRIORITY), in which case this maps directly to the UP (priority - 256) for testing. | ||
| + | |||
| + | The IPv4 TOS field maps into the UP as follows, but keep in mind that the lowest two bits of the TOS are reserved (or used for ECN): | ||
| + | |**TOS** |**UP** | | ||
| + | |0 - 31 |0 | | ||
| + | |32 - 63 |1 | | ||
| + | |... | | ||
| + | |224 - 255 |7 | | ||
| + | |||
| + | **DSCP **(RFC 2474)**:** | ||
| + | |||
| + | Alternatively you can set the IP_TOS with setsockopt, then you need to ask how DSCP maps into the UP. DSCP is defined in the Differentiated Services ([[DiffServ|DiffServ]]) model as the six most significant bits of the [[DiffServ|DiffServ]](DS) Field. | ||
| + | |DS5 (P2) |DS4 (P1) |DS3 (P0) |DS2 |DS1 |DS0 |ECN |ECN | | ||
| + | |||
| + | The classes of DSCP in wide usage are: | ||
| + | |**DSCP Class** |**Codepoint(s)** | | ||
| + | |Default |0x00 | | ||
| + | |Expedited Forwarding (EF) |0x2E | | ||
| + | |Assured Forwarding (AF1) |0xA, 0xC, 0xE | | ||
| + | |Assured Forwarding (AF2) |0x12, 0x14, 0x16 | | ||
| + | |Assured Forwarding (AF3) |0x1A, 0x1C, 0x1E | | ||
| + | |Assured Forwarding (AF4) |0x22, 0x24, 0x26 | | ||
| + | |||
| + | The 3 Precedence bits of DSCP (**P2, P1, P0**) are used for mapping to 802.1D tags and AC values as: | ||
| + | |**P2 P1 P0** |**802.1D** |**AC** | | ||
| + | |0 0 0 |0 |BE | | ||
| + | |0 0 1 |1 |BK | | ||
| + | |0 1 0 |2 |BK | | ||
| + | |0 1 1 |3 |BE | | ||
| + | |1 0 0 |4 |VI | | ||
| + | |1 0 1 |5 |VI | | ||
| + | |1 1 0 |6 |VO | | ||
| + | |1 1 1 |7 |VO | | ||
| + | |||
| + | **Testing**: | ||
| + | * Use ping ( with -Q option, see manpage ) | ||
| + | * use iperf: <code>iperf -S 0xE0 -c <IP></code> | ||
| + | * Use iptables. Example session with 2 iperf streams: | ||
| + | * * iptables -t mangle -A OUTPUT -p tcp –dport 5000 -j DSCP –set-dscp-class "EF" | ||
| + | * * iptables -t mangle -A OUTPUT -p tcp –dport 5001 -j DSCP –set-dscp-class "BE" | ||
en/developers/documentation/mac80211/queues.txt · Last modified: 2015/01/26 09:49 (external edit)
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