300-070 · Question #180
By default, what value is voice traffic marked as on a Cisco Catalyst Switch?
The correct answer is D. DSCP EF value 46, Cos 5. By default, Cisco Catalyst switches mark voice traffic (RTP media bearer) with DSCP EF (Expedited Forwarding), which has a decimal value of 46 (binary 101110), and a Class of Service (CoS) value of 5. DSCP EF provides the highest priority PHB (Per-Hop Behavior) in DiffServ and…
Question
By default, what value is voice traffic marked as on a Cisco Catalyst Switch?
Options
- ADSCP CAS6 value 21, Cos 3
- BDSCP AF21 value 46, Cos 5
- CDSCP EF value 46, Cos 7
- DDSCP EF value 46, Cos 5
How the community answered
(43 responses)- A2% (1)
- B7% (3)
- C2% (1)
- D88% (38)
Explanation
By default, Cisco Catalyst switches mark voice traffic (RTP media bearer) with DSCP EF (Expedited Forwarding), which has a decimal value of 46 (binary 101110), and a Class of Service (CoS) value of 5. DSCP EF provides the highest priority PHB (Per-Hop Behavior) in DiffServ and is the standard marking for delay-sensitive voice traffic. CoS 5 is the Layer 2 802.1p priority bit value associated with voice media. CoS 3 is typically used for call signaling (not bearer), and CoS 7 is reserved for network control traffic, not voice. Note that 'DSCP AF21 value 46' in option B is incorrect because AF21 has a value of 18, not 46.
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