Panasonic KX-NS1000 Installation Manual page 349

Required Bandwidth for Each IP Extension Card
To allow all IP telephones to make calls simultaneously, it is necessary to keep available the bandwidth required
by an IP extension card with the maximum number of IP telephones connected.
Provided below is the formula to calculate the amount of bandwidth required for each IP extension card.
When using the V-IPEXT32/V-SIPEXT32 card:
Required Bandwidth = (Required Bandwidth per IP telephone ´ 32)
Bandwidth Assessment for V-IPGW16 Card
Required Bandwidth for One VoIP Channel
The required bandwidth depends on what combination of codecs and packet sending intervals is used. Keep
in mind the following points about the type of codec and packet sending interval, in terms of the speech quality:
•
The speech quality of the G.711 codec is higher than that of the G.729A codec.
•
The shorter the packet sending interval, the higher the speech quality.
•
The higher the speech quality the V-IPGW16 card provides, the more bandwidth the card requires.
Via LAN
Codec
G.711
G.729A
Via WAN (PPP: Point-to-Point Protocol)
Codec
G.711
G.729A
Bandwidth Calculation
Provided below is the formula to find out the amount of bandwidth required for VoIP communications:
Required Bandwidth
= (No. of Fax Machines ´ Required Bandwidth for the G.711 codec) +
[(16 - No. of Fax Machines) ´ Required Bandwidth for Voice Communication]
Example
Consider the following case as an example:
•
Communication: via LAN
•
No. of Fax Machines: 2
•
G.711 Packet Sending Interval: 20 ms (requiring 87.2 kbps per channel)
•
G.729A Packet Sending Interval for Voice Communication: 20 ms (requiring 31.2 kbps per channel)
In this case, the required bandwidth will be as follows:
Required Bandwidth
= (2 ´ 87.2) + [(16 - 2) ´ 31.2]
= 611.2 (kbps)
20 ms 30 ms
87.2 kbps 79.5 kbps
31.2 kbps 23.5 kbps
20 ms 30 ms
84 kbps 77.3 kbps
28 kbps 21 kbps
Packet Sending Interval
40 ms
75.6 kbps
19.6 kbps
Packet Sending Interval
40 ms
74 kbps
18 kbps
8.2.3 Bandwidth Assessment
60 ms 90 ms
71.7 kbps —
15.7 kbps —
60 ms 90 ms
70.7 kbps —
14.7 kbps —
Installation Manual 349