Factors that effectthe real-time capacity 113
Tabl e 17
Silence Suppression disabled TLAN Ethernet and WANIP bandwidth usage per IP Trunk 3.01
(and later) port
Codec
type
Codec
Multi -
frame
duration
(ms)
See Note
8.
Voice/
fax
paylo
ad
size
(bytes)
IP
header
size
(bytes)
Ethern
et
header
size
(bytes)
Full-du
plex
Ethern
et
Bandw
idth
(bps)
PPP
WAN
Bandw
idth
(bps)
See
Note
9.
Frame
Relay
WAN
bandw
idth
(bps)
ATM
WAN
bandwi
dth
(bps)
G.711 10 80 40 26 116,800 101,600 102,400 127,200
(64 kbit/s)
voice 20 160 40 26 90,400 82,800 83,200 106,000
30 240 40 26 81,600 76,533 76,800 84,800
10 10 40 26 60,800 45,600 46,400 84,800
20 20 40 26 34,400 26,800 27,200 42,400
DSP profile
AB/G.729A
(8kbit/s)
voice 30 30 40 26 25,600 20,533 20,800 28,267
G.723.1
(5.3 kbit/s)
voice
30 20 40 26 22,933 17,867 18,133 26,571
G723.1 (6.3
kbit/s) 30 24 40 26 24,000 18,933 19,200 28,267
16.6 30 40 26 46,265 37,108 37,590 50,600
T.30/T.38
G3 Fax 25 30 40 26 30,720 24,960 24,960 33,900
Based on voice multiframe encapsulation for Realtime Transport Protocol per H.323 V2.
The bolded rows contain the default payload/packet size for each codec in TM 3.1.
TLAN subnet data rate is the effective Ethernet bandwidth consumption.
TLAN subnet kbit/s for voice traffic = 2*Ethernet frame bits*8/frame duration in ms
WAN kbit/s for voice traffic = IP packet bytes*8/frame duration in ms
Overhead (RTP/UDP header + IP header) of packets over the voice payload multiframe is 40 bytes;
overhead of Ethernet frame over IP packet is 26 bytes.
An Interframe gap is not included in the above bandwidth calculation,because ofthe low probability
of occurring in this type of application.
Length of speech captured at each end. By definition, payload is one way.
These values do not include overhead from the network header (IEEE 802.3) that is automatically
added at the TLAN subnet link. To determine the approximate bandwidth used on the TLAN subnet
when including the network header, divide the values in the column "Bandwidth use on TLAN
subnet in kbit/s (two way)" by 2.
Nortel Communication Server 1000
IP TrunkFundamentals
NN43001-563 02.01 Standard
Release 5.5 21December 2007
Copyright© 2007, Nor tel Networks
.