Exam 350-801 topic 1 question 77 discussion

It is just like the G.711 for ethernet frames.

Calculating the overhead: IP header: 20 bytes UDP header: 8 bytes RTP header: 12 bytes Ethernet header: 18 bytes Total overhead per packet: 20 (IP) + 8 (UDP) + 12 (RTP) + 18 (Ethernet) = 58 bytes Total packet size: Voice payload: 160 bytes Total packet size: 160 (payload) + 58 (overhead) = 218 bytes Bandwidth calculation: Packet size: 218 bytes * 8 bits/byte = 1744 bits per packet Since the codec sample interval is 20 ms, there are 50 packets per second (1000 ms / 20 ms). Total bandwidth: 1744 bits/packet * 50 packets/second = 87,200 bps or 87.2 kbps Thus, the size of the Ethernet bandwidth per call is: D. 87.2 kbps

Voice Payload Size: Given as 160 bytes every 20 ms. Packets Per Second (PPS): Since the voice payload is sent every 20 ms, there are 50 packets per second (1000 ms / 20 ms = 50). Total Packet Size: This includes the voice payload plus the overhead from the Layer 2 (L2) header and the IP/UDP/RTP headers. The typical L2 header for Ethernet is 18 bytes, and the IP/UDP/RTP header is 40 bytes. Bandwidth Calculation: The total bandwidth per call is the total packet size multiplied by the PPS and then converted to bits per second (since 1 byte = 8 bits). Using the formula: Bandwidth=(L2 header+IP/UDP/RTP header+voice payload size)×PPS×8 We can plug in the values: Bandwidth=(18 bytes+40 bytes+160 bytes)×50×8 Bandwidth=(218 bytes)×50×8 Bandwidth=10900 bytes/s×8 Bandwidth=87200 bits/s or 87.2 kbps So, the Ethernet bandwidth size per call should be 87.2 kbps

To calculate the Ethernet bandwidth per call, we need to take into account the total number of bytes per second in each direction (transmit and receive) and add additional overhead for Ethernet, IP, and UDP headers. The total number of bytes per second is calculated as follows: 160 bytes per 20 ms = (160 bytes/20 ms) x (50 packets/s) = 8000 bytes/s The bit rate is 64 kbps, so we need to add an additional 8 kbps for overhead: 64 kbps + 8 kbps = 72 kbps The total number of bytes per second including overhead is: 72,000 bps / 8 bits per byte = 9,000 bytes/s Adding additional overhead for Ethernet, IP, and UDP headers, we can estimate that the total number of bytes per second will be approximately 12,000 bytes/s in each direction. Therefore, the Ethernet bandwidth per call should be: 12,000 bytes/s x 8 bits per byte = 96 kbps Therefore, the correct answer is D. 87.2 kbps is not sufficient to support the required bandwidth per call.

87.2 kbps; same here. it is comparable with g.711, g.736 is not existing https://www.cisco.com/c/en/us/support/docs/voice/voice-quality/7934-bwidth-consume.html -> VoIP - Per Call Bandwidth

Answer should be D. G.736 doesn’t exist as a codec. The figures line up with g711 or g722, but the codec isn’t the important part. If we take the numbers given and run the calculations, the answer is 87.2 Kbps. https://www.cisco.com/c/en/us/support/docs/voice/voice-quality/7934-bwidth-consume.html

All details match with G711 protocol, for which the calculation is : (160+(40+18))/160 x 64 =87.2 kbps https://www.cisco.com/c/en/us/support/docs/voice/voice-quality/7934-bwidth-consume.html Codec Information Bandwidth Calculations Codec & Bit Rate (Kbps) Codec Sample Size (Bytes) Codec Sample Interval (ms) Mean Opinion Score (MOS) Voice Payload Size (Bytes) Voice Payload Size (ms) Packets Per Second (PPS) Bandwidth MP or FRF.12 (Kbps) Bandwidth w/cRTP MP or FRF.12 (Kbps) Bandwidth Ethernet (Kbps) G.711 (64 Kbps) 80 Bytes 10 ms 4.1 160 Bytes 20 ms 50 82.8 Kbps 67.6 Kbps 87.2 Kbp