QoS Mapping Reference - DSCP → 802.1p UP → 802.11e AC | RFC 8325 (updated mapping), RFC 4594 (DSCP usage), IEEE 802.11e11 rows#
| Traffic Type | DSCP (decimal) | DSCP (hex) | DSCP Name | 802.1p UP (0-7) | 802.11e AC | WMM Queue | CWmin/CWmax | Engineering Notes |
|---|---|---|---|---|---|---|---|---|
| Network Control (BGP/OSPF) | 48 | 0x30 | CS6 | 7 | AC_VO | VO | 3/7 | Router-to-router routing protocols. Highest priority. Never throttle. |
| Telephony / VoIP RTP | 46 | 0x2E | EF (Expedited Fwd) | 5 or 6 | AC_VO | VO | 3/7 | G.711/G.729 voice. 20 ms packets. Requires <150 ms one-way latency. EF = dedicated bandwidth. |
| Signaling (SIP/H.323) | 40 | 0x28 | CS5 | 5 | AC_VO | VO | 3/7 | Call setup/teardown. Small packets, low volume. Higher than data but lower than voice media. |
| Video conferencing (RTP video) | 34 | 0x22 | AF41 | 4 | AC_VI | VI | 7/15 | Interactive video (Zoom, Teams video). Intolerant of jitter. Separate queue from voice. |
| Streaming video | 32 | 0x20 | CS4 | 4 | AC_VI | VI | 7/15 | Pre-buffered video (Netflix, YouTube). More latency tolerant than interactive. Some implementations map to BE. |
| Multimedia streaming | 26 | 0x1A | AF31 | 4 | AC_VI | VI | 7/15 | RFC 4594: multimedia streaming. Consistent bandwidth needed. |
| Business-critical data | 18 | 0x12 | AF21 | 0 or 3 | AC_BE | BE | 15/1023 | ERP, CRM, business apps. Elevated priority within best effort class. |
| High-throughput data | 10 | 0x0A | AF11 | 0 | AC_BE | BE | 15/1023 | Bulk transfers with some priority. FTP, large file sync. |
| Best Effort (default) | 0 | 0x00 | CS0 / BE | 0 | AC_BE | BE | 15/1023 | Default IP traffic. HTTP, HTTPS (unclassified), most internet traffic. |
| Low-Priority / Scavenger | 8 | 0x08 | CS1 | 1 | AC_BK | BK | 15/1023 | Peer-to-peer, OS updates, background backup. Deliberately deprioritized. |
| Background | 2 | 0x02 | -- | 1 | AC_BK | BK | 15/1023 | Lowest priority. Bulk background transfers. |
EDCA Parameters - IEEE 802.11-2020 §26.3.2 | Default values (AP advertisement in beacon / Assoc Resp)4 rows#
| Access Category | AIFSN (slots) | CWmin | CWmax | TXOP Limit (µs) | TXOP Limit (ms) | Priority Order | Typical Traffic | Notes |
|---|---|---|---|---|---|---|---|---|
| AC_VO (Voice) | 2 | 3 | 7 | 1504 µs | 1.504 ms | 1 (highest) | VoIP RTP, SIP signaling | Smallest CW + shortest AIFS = fastest medium access. TXOP = 1504 µs = enough for one G.711 20ms frame. |
| AC_VI (Video) | 2 | 7 | 15 | 3008 µs | 3.008 ms | 2 | Video RTP, conferencing | Medium CW. TXOP = 3008 µs for larger video frames. |
| AC_BE (Best Effort) | 3 | 15 | 1023 | 0 µs | 0 (TXOP disabled) | 3 | Web browsing, HTTPS, email | TXOP=0 means one MPDU/AMPDU then must re-contend. Most traffic. |
| AC_BK (Background) | 7 | 15 | 1023 | 0 µs | 0 (TXOP disabled) | 4 (lowest) | Backups, P2P, OS updates | Longest AIFS (7 slots) = waits longer before contending. Deliberately penalized. |
Common QoS Design Mistakes & Fixes6 rows#
| Access Category | AIFSN (slots) | CWmin | CWmax | TXOP Limit (µs) | TXOP Limit (ms) | Priority Order | Typical Traffic | Notes |
|---|---|---|---|---|---|---|---|---|
| Mistake | Impact | Correct Approach | RFC / Standard | - | - | - | - | - |
| Not classifying traffic at AP (all flows = BE) | VoIP packets compete equally with YouTube → jitter and packet loss on voice | Configure DSCP trust on AP/WLC, apply DSCP-to-UP-to-AC mapping per RFC 8325 | RFC 8325 | - | - | - | - | - |
| Using CS6/CS7 for voice instead of EF | Router control traffic shares queue with voice → congestion during routing events | EF (DSCP 46) for voice media. CS5 for signaling. Never use CS6/CS7 for user traffic. | RFC 4594 | - | - | - | - | - |
| 40 MHz in 2.4 GHz causing AC_VO starvation | Only 1 non-overlapping 40 MHz channel → severe CCI → retransmissions fill VO queue | Use 20 MHz channels in 2.4 GHz for voice deployments | Wi-Fi Alliance Voice-Enterprise | - | - | - | - | - |
| DSCP remarking at NAT boundary | DSCP marking stripped by ISP or NAT device → all traffic becomes BE at far end | Use DSCP marking end-to-end. Ensure firewall/NAT rules preserve DSCP. | RFC 2474 | - | - | - | - | - |
| Multicast video at basic rate (1 Mbps) | High-throughput multicast stream sent at 1 Mbps → consumes enormous airtime | Convert multicast to unicast per client (mcast-to-ucast conversion in AP). Or raise basic rates. | IEEE 802.11-2020 §11.2.1.7 | - | - | - | - | - |