Home » Cisco » 400-051 » How much bandwidth should be allocated to the strict priority queue for six VoIP calls that use a G.729 codec over a multilink PPP link with cRTP enabled?
Assume 20 bytes of voice payload, 6 bytes for the Layer 2 header, 1 byte for the end-of-frame flag, and the IP, UDP, and RTP headers are compressed to 2 bytes, how much bandwidth should be allocated to the strict priority queue for six VoIP calls that use a G.729 codec over a multilink PPP link with cRTP enabled?
A. 80.4 kb/s
B. 91.2 kb/s
C. 78.4 kb/s
D. 69.6 kb/s
E. 62.4 kb/s
Correct Answer: D
Explanation/Reference:
Explanation:
Voice payloads are encapsulated by RTP, then by UDP, then by IP. A Layer 2 header of the correct format is applied; the type obviously depends on the link technology in use by each router interface: A single voice call generates two one-way RTP/UDP/IP packet streams. UDP provides multiplexing and checksum capability; RTP provides payload identification, timestamps, and sequence numbering.
https://www.cisco.com/c/en/us/support/docs/voice/voice-quality/7934-bwidth-consume.html
Bandwidth w/cRTP MP or FRF.12 (Kbps) = G.729 @ 11.6