D-SNC-DY-00 · Question #38
Which of the following can be used to classify traffic for QoS in SONiC?
The correct answer is A. IP addresses B. VLAN IDs C. DSCP (Differentiated Services Code Point) values. In SONiC, QoS traffic classification operates across multiple layers: IP addresses enable policy-based routing and ACL-driven QoS rules at Layer 3, VLAN IDs allow traffic segmentation and prioritization at Layer 2 based on logical network groupings, and DSCP values are the most…
Question
Which of the following can be used to classify traffic for QoS in SONiC?
Options
- AIP addresses
- BVLAN IDs
- CDSCP (Differentiated Services Code Point) values
- DMAC addresses
How the community answered
(30 responses)- A93% (28)
- D7% (2)
Explanation
In SONiC, QoS traffic classification operates across multiple layers: IP addresses enable policy-based routing and ACL-driven QoS rules at Layer 3, VLAN IDs allow traffic segmentation and prioritization at Layer 2 based on logical network groupings, and DSCP values are the most common QoS marker - embedded in the IP header's ToS field and natively recognized by SONiC's DSCP-to-TC (Traffic Class) mapping tables.
MAC addresses (D) is incorrect because SONiC's QoS pipeline does not use MAC addresses as a classification criterion - MAC-based decisions belong to Layer 2 switching logic (like FDB lookups), not QoS policy enforcement.
Memory tip: Think "IVD = In, VLANs, DSCP" - the three classifiers all give SONiC meaningful context about traffic intent, while MAC addresses only tell you where a frame came from, which isn't useful for prioritization decisions.
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