1. Why ? VOIP Analysis using OPNET Objective
Assume we have a pre-existing data network
The network managers want to merge voice and data network into one
Why ?
Cost effective, easier to run, manage and maintain
Questions to be asked
Will my existing network support VoIP and satisfy the standardized QoS?
If yes, how many simultaneous VoIP calls can be made without any hardware upgrade

2. End to End component of VoIP
BANDWIDTH REQUIREMENTS
ENCODER:
Encoder used- PCM (G.711)= 64 Kbps
1 Packet = 20 msec of voice, Therefore 50 Packets/sec
64 Kbps/ 50 * 8= 160 Bytes / Packet
PACKETIZER:
-Header Information : 66 Bytes
-Total Packet Size going through the network : 226 Bytes
- 226 * 8 * 50 Packets= 90.4 Kbps BW required for one call
DELAY REQUIREMENT
D pack= A/D conversion (5 msec)+ Packetization at source (20 msec)= 25 msec
D play= Jitter Buffer Delay + De-packetization (5 msec)= 45 msec
Therefore the network delay = 150 msec ( Mouth- Ear delay QoS requirement) – 70 = 80 msec

3. Cisco 2512
Switch 2
Switch 1

5. Result=
0.80 msec delay in the packet is
When 2 min 20 seconds- 50 seconds = 90 seconds
And every two seconds three calls are generated, therefore
135 calls can be made in total

6. Topology

7. Wireless Delay

8. Wireless load

9. Wi-Fi throughput *Traffic received

10. OPNET academic edition