During deployment, a network engineer notices that voice traffic is not being tagged correctly as it traverses the network. Which COS to DSCP map must be modified to ensure that voice traffic is…

The correct answer is A. COS of 5 to DSCP 46. Per IEEE 802.1p and IETF RFC 4594 standards, voice bearer traffic (RTP) is assigned CoS 5 at Layer 2 and DSCP 46 (Expedited Forwarding, EF) at Layer 3. When a device maps CoS values to DSCP values at a trust boundary (e.g., at a switch uplink or WLC), CoS 5 must map to DSCP 46…

Wireless Deployment

Question

During deployment, a network engineer notices that voice traffic is not being tagged correctly as it traverses the network. Which COS to DSCP map must be modified to ensure that voice traffic is treated properly?

Options

ACOS of 5 to DSCP 46
BCOS of 7 to DSCP 48
CCOS of 6 to DSCP 46
DCOS of 3 to DSCP of 26

How the community answered

(40 responses)

A
93% (37)
C
3% (1)
D
5% (2)

Explanation

Per IEEE 802.1p and IETF RFC 4594 standards, voice bearer traffic (RTP) is assigned CoS 5 at Layer 2 and DSCP 46 (Expedited Forwarding, EF) at Layer 3. When a device maps CoS values to DSCP values at a trust boundary (e.g., at a switch uplink or WLC), CoS 5 must map to DSCP 46 to preserve proper QoS treatment end-to-end. The other options are incorrect: CoS 7 → DSCP 48 (NC1) is for network control traffic; CoS 6 → DSCP 46 is a non-standard mapping (CoS 6 is typically network control); and CoS 3 → DSCP 26 is used for call signaling or low-priority data, not voice bearer.

Topics

#QoS#CoS to DSCP mapping#voice traffic#EF DSCP 46

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