In which of the following scenarios is self-generated traffic QoS (sgt-QoS) useful?

Question

Options

• AEXP markings on transit control traffic are not set correctly.
• BThe priority of all self-generated traffic needs to be lowered to allow all other traffic to take
• CThe priority of various control packets requires special treatment throughout the network.
• DThe BGP process is consuming too many CPU cycles and is impacting OSPF performance.

• A
  7% (2)
• B
  3% (1)
• C
  77% (23)
• D
  13% (4)

Explanation

sgt-QoS enables a router to apply differentiated QoS markings (e.g., DSCP) to the various control-plane packets it originates itself - BGP updates, OSPF hellos, LDP messages, etc. - so those packets receive the correct forwarding treatment as they traverse the network. Option C is correct because different control protocols often have different priority requirements (e.g., OSPF hellos are more time-sensitive than BGP keepalives), and sgt-QoS is precisely the mechanism to assign each type its appropriate marking at the source.

Why the distractors are wrong:

• A is wrong because EXP markings on transit traffic are set by the forwarding plane as packets pass through - that's a remarking/classification issue, not a self-generated traffic problem.
• B is wrong because sgt-QoS provides granular, per-protocol control, not a blunt global priority reduction - uniformly lowering all self-generated traffic would be counterproductive and dangerous for critical protocols.
• D describes a CPU/process scheduling problem on the local device, which is addressed by Control Plane Policing (CoPP) or process priority tuning, not QoS markings for network transit.

Memory tip: Think "SGT = Self-Generated Traffic gets Tags" - the router stamps its own outgoing control packets with QoS tags so the rest of the network knows how to treat each protocol differently.

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