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
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.