ThroughPacket is essentially a trunking technique. It concatenates the data from multiple channels into a single packet. This technique significantly reduces the number of packets that the gateway needs to transmit each second. By sending fewer packets through the network, ThroughPacket reduces the load on the network routers. Since routing performance (for example, jitter and dropped packets) tends to decrease with increased packet rate, ThroughPacket can reduce routing costs and improve voice quality. Because packet traffic in IP networks tends to take place in bursts, reducing the packet rate from any source can reduce the chances of packet loss due to router congestion at peak periods.
The following table compares the packet rate for 120 simplex RTP streams versus a single ThroughPacket stream that multiplexes the 120 voice streams. The TPKT packet data rate efficiency factor column shows results for different standard vocoders. The greatest benefits occur when using the low bit rate vocoders.
|
Vocoder type |
Vocoder rate (kbit/s) |
Default payload (ms) |
Packet rate for 120 RTP streams (packets/sec) |
Packet rate for equivalent TPKT stream (packets/sec) |
TPKT packet data rate efficiency factor |
|
G.711 |
64.00 |
20 |
6,000.00 |
750.00 |
8.00 |
|
G.726 |
32.00 |
20 |
6,000.00 |
375.00 |
16.00 |
|
G.723.1 |
6.40 |
30 |
4,000.00 |
81.63 |
49.00 |
|
G.723.1 |
5.33 |
30 |
4,000.00 |
70.18 |
57.00 |
|
G.729A |
8.00 |
20 |
6,000.00 |
105.26 |
57.00 |