Command Reference Guide

40 ● compression 3Com Router 5000 Family and Router 6000 Family
Command Reference
Actual network bandwidth is related to packet assembly interval and network
structure. The longer the packet assembly interval is, the closer the network
bandwidth is to the media stream bandwidth. More headers consume more
bandwidth. Longer packet assembly interval results in longer fixed coding latency.
The following tables show the relevant packet assembly parameters without IPHC
compression, including packet assembly interval, bytes coded in a time unit, and
network bandwidth, etc. Thus, you can choose a suitable codec algorithm according
to idle and busy status of the line and network situations more conveniently.
Tabl e 2 G.711 algorithm (A-law and µ-law)
Tabl e 3 G.729 algorithm
Tabl e 4 G.723 r63 algorithm
Tabl e 5 G.723 r53 algorithm
Tabl e 6 G.726 r16 algorithm
Packet
assembly
interval
Bytes
coded in a
time unit
Packet
length IP
Network
bandwidth
IP
Packet
length
IP+PPP
Network
bandwidth
IP+PPP
Coding
latency
10 ms 80 120 96 kbps 126 100.8 kbps 10 ms
20 ms 160 200 80 kbps 206 82.4 kbps 20 ms
30 ms 240 280 74.7 kbps 286 76.3 kbps 30 ms
G.711 algorithm (A-law and µ-law): media stream bandwidth 64kbps, minimum packet assembly
interval 10 ms.
Packet
assembly
interval
Bytes
coded in a
time unit
Packet
length IP
Network
bandwidth
IP
Packet
length
IP+PPP
Network
bandwidth
IP+PPP
Coding
latency
10 ms 10 50 40 kbps 56 44.8 kbps 10 ms
20 ms 20 60 24 kbps 66 26.4 kbps 20 ms
30 ms 30 70 18.7 kbps 76 20.3 kbps 30 ms
G.729 algorithm: media stream bandwidth 8 kbps, minimum packet assembly interval 10 ms.
Packet
assembly
interval
Bytes
coded in a
time unit
Packet
length IP
Network
bandwidth
IP
Packet
length
IP+PPP
Network
bandwidth
IP+PPP
Coding
latency
30 ms 24 64 16.8 kbps 70 18.4 kbps 30 ms
60 ms 48 88 11.6 kbps 94 12.3 kbps 60 ms
90 ms 72 112 9.8 kbps 118 10.3 kbps 90 ms
G.729 algorithm: media stream bandwidth 8 kbps, minimum packet assembly interval 10 ms.
Packet
assembly
interval
Bytes
coded in a
time unit
Packet
length IP
Network
bandwidth
IP
Packet
length
IP+PPP
Network
bandwidth
IP+PPP
Coding
latency
30 ms 20 60 15.9 kbps 66 17.5 kbps 30 ms
60 ms 40 80 10.6 kbps 86 11.4 kbps 60 ms
90 ms 60 100 8.8 kbps 106 9.3 kbps 90 ms
G.723 r53 algorithm: media stream bandwidth 5.3 kbps, minimum packet assembly interval 30
ms.
Packet
assembly
interval
Bytes
coded in a
time unit
Packet
length IP
Network
bandwidth
IP
Packet
length
IP+PPP
Network
bandwidth
IP+PPP
Coding
latency
10 ms 20 60 48 kbps 66 52.8 kbps 10 ms
G.726 r16 algorithm: media stream bandwidth 16 kbps, minimum packet assembly interval 10 ms.