Specifications

hg-09.fm
A31003-H3580-M103-2-76A9, 01-2009
HiPath 3000/5000 V8 - HG 1500 V8, Administrator Documentation
9-5
Nur für den internen Gebrauch
Technical Concepts
Bandwidth Requirements in LAN/WAN Environments
The WLAN load is calculated for a single direction. As WLAN channels usually contain chan-
nels in both directions, this is the same as the bandwidth requirement, for example, for one
ISDN channel.
The overhead is calculated as follows:
A "compressed header" is usually used for RTP/UDP/IP Header compression. In addition every
5 seconds a full header is sent (total = 46 octets).
The rule of thumb for calculating the bandwidth requirement for n parallel VoIP connections with
G.711 (one frame per RTP packet) is:
BandwidthLAN = n × (180voice payload + 0.4RTPC)
BandwidthWAN = n × (82voice payload + 0.4RTPC)
The approximate values for voice payload changes for other codecs or packet values. In addi-
tion, the bandwidth for Attendant P, call charge information, and other applications must also
be taken into account.
G.729A 1 20 20 66 230% 26.4 28 11.2
G.729A 2 40 40 86 115% 17.2 48 9.6
G.729A 3 60 60 106 77% 14.1 68 9.1
RTCP 5000 230 0.4 0.4
Protocol Bytes
RTP header 12
UDP header 8
IP header 20
PPP 9
Total 46
Compressed header 8
Table 9-5 Overhead Calculation
Codec Packeti-
zing para-
meter
Packet
interval/
Frame
size
(msec)
Payload
(bytes)
Packet
length
(bytes)
Payload pa-
cket (over-
head
in %)
WAN
load
(Kbps)
Packet
length
with
header
compres-
sion
(bytes)
WAN
load with
header
compres-
sion
(Kbps)
Table 9-4 WAN bandwidth requirements according to Codec