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350-801 · Question #357

An engineer is going to redesign a network, and while looking at the QoS configuration, the engineer sees that a portion of the network is marked with AF42. Which type of traffic is marked with this…

The correct answer is D. video conference. In Differentiated Services Code Point (DSCP) classification, AF42 is a specific marking used for interactive video conferencing. This marking prioritizes video traffic to ensure good quality without being as critical as voice.

Media and QoS

Question

An engineer is going to redesign a network, and while looking at the QoS configuration, the engineer sees that a portion of the network is marked with AF42. Which type of traffic is marked with this tag?

Options

  • Avoice
  • Bstreaming video
  • Csignaling
  • Dvideo conference

How the community answered

(37 responses)
  • A
    3% (1)
  • C
    5% (2)
  • D
    92% (34)

Why each option

In Differentiated Services Code Point (DSCP) classification, AF42 is a specific marking used for interactive video conferencing. This marking prioritizes video traffic to ensure good quality without being as critical as voice.

Avoice

Voice traffic is typically marked with DSCP EF (Expedited Forwarding), not AF42, due to its extremely low latency and jitter requirements.

Bstreaming video

While streaming video can use AF markings, AF42 is specifically for interactive video conferencing, which has stricter real-time requirements than non-interactive streaming video.

Csignaling

Signaling traffic (e.g., SIP, H.323) is typically marked with AF31 or CS3, not AF42.

Dvideo conferenceCorrect

AF42 is a DSCP marking within the Assured Forwarding class 4, specifically indicating interactive video conferencing traffic, which requires good quality but is less sensitive to loss than voice.

Concept tested: DSCP classification for video conferencing

Source: https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoS-SRND-Book.html

Topics

#QoS#DSCP#AF42#Video Conferencing

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