Home » Cisco » 400-051 » How much bandwidth should be allocated to the strict priority queue for three VoIP calls that use a G.722 codec over an Ethernet network?
Assume 18 bytes for the Layer 2 header and a 10-millisecond voice payload, how much bandwidth should be allocated to the strict priority queue for three VoIP calls that use a G.722 codec over an Ethernet network?
A. 331.2 kb/s
B. 347.8 kb/s
C. 261.6 kb/s
D. 274.7 kb/s
E. 238.4 kb/s
Correct Answer: A
Explanation/Reference:
Reference: http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml
40 bytes IP + 18 bytes for Layer 2 + 80 bytes for the 10ms codec sample = 138 bytes per 10ms = 1104 bits per 10 ms = 110400 bits per second
3 calls equal 331200 bits per second or 311,2 kb/s
A is correct when using 10ms payload.
C or D is what the TAC BW calculator computes. Not getting why it is A
Bandwidth Used for All Calls (RTP Only) 261.60 kbps (Bandwidth per Call) * (Number of Calls)
Total Bandwidth (including all Message Overhead) 274.68 kbps Same as above + 5.0% Overhead