Match each Quality of Service (QoS) concept or mechanism on the left to its corresponding … — Cisco CCNA

Match each Quality of Service (QoS) concept or mechanism on the left to its corresponding operational characteristic or header specification on the right.

Expedited Forwarding (EF)DSCP value 46 ( $101110_2$ ) providing strict delay and jitter guarantees for real-time voice traffic.
Class-Based Weighted Fair Queuing (CBWFQ)Queuing algorithm that allocates guaranteed minimum bandwidth percentages to defined classes without strict priority handling.
Traffic PolicingTraffic conditioning mechanism that enforces rate limits by immediately dropping or remarking excess packets without buffering.
Class of Service (CoS)3-bit Layer 2 marking field located within the IEEE 802.1Q VLAN tag header.

Answer

Expedited Forwarding (EF) matches DSCP value 46; Class-Based Weighted Fair Queuing (CBWFQ) matches bandwidth allocation without strict priority; Traffic Policing matches dropping or remarking excess packets without buffering; Class of Service (CoS) matches the 3-bit Layer 2 802.1Q header field.

Each QoS concept correctly aligns with its protocol layer, header field, or operational mechanism: Expedited Forwarding (EF) maps to DSCP 46; CBWFQ provides minimum bandwidth guarantees across user-defined classes; Traffic Policing enforces rate bounds by dropping/remarking packets without using buffers; and CoS utilizes the 3-bit field inside IEEE 802.1Q headers.

Step-by-Step Solution

Identify the DSCP Per-Hop Behavior (PHB) designated for delay-sensitive voice payload.

Expedited Forwarding (EF) corresponds to DSCP value 46 (

101110_2

EF PHB ensures a guaranteed service rate with minimal delay and jitter for real-time applications.

Analyze how Class-Based Weighted Fair Queuing (CBWFQ) manages bandwidth.

CBWFQ allocates guaranteed minimum bandwidth percentages to defined classes.

Standard CBWFQ guarantees bandwidth per class during congestion but does not offer strict latency prioritization unless paired with Low Latency Queuing (LLQ).

Distinguish Traffic Policing from Traffic Shaping mechanics.

Policing enforces rate limits by immediately dropping or remarking excess packets without queue buffers.

Traffic shaping buffers excess traffic to smooth burst profiles, whereas policing acts instantaneously without memory buffering.

Evaluate Layer 2 QoS marking standards.

Class of Service (CoS) resides in the 3-bit Priority Code Point (PCP) field within an IEEE 802.1Q Ethernet tag.

CoS operates strictly at Layer 2 across trunk links and allows values from 0 through 7.

Key Concept

QoS Per-Hop Behaviors, Marking, Queuing, and Traffic Conditioning

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