Appendix – Specifications
Strata Net IP and IPT Bandwidth Requirements
Strata CIX General Description
129
Strata Net IP and IPT Bandwidth Requirements
The amount of bandwidth required for communications over a particular IP network segment
depends on the number of voice channels supported, the anticipated call setup traffic, and how
much other data network traffic is present.
The quality of service (Excellent, Good, Fair, and Poor) provided by Strata Net IP channels and IP
telephones depends heavily on the LAN parameters as shown in
Table 25
. This table shows the
amount of bandwidth required for each Strata Net IP voice call (without data traffic) based on the
interval and the CODEC.
Table 25
Strata Net IP and IPT Quality of Service
IP Network Quality Parameters
Speech
Excellent: No one
perceives delay.
1
1. Ratings of Excellent, Good, Fair, Poor were based on the tester in a quiet room and the tester could not see the
other call party.
Good: Very few
people perceive
delay.
1
Fair: Some people
may perceive
delay.
1
Poor: Many people
may perceive delay.
1
IPT is usable even
with a “Poor” rating if
delay is acceptable.
Latency (Round trip delay)
2
2. When selecting router equipment, the Latency, Jitter, Packet loss and Packet error conditions above should be
considered as well as the bandwidth. Bandwidth can be calculated with the CODEC and packet size. For better
results, more bandwidth may be required, depending on the amount of overall data traffic. For more details on QoS
refer to “A Handbook for Successful VoIP Deployment: Network Testing, QoS, and More” by John Q. Walker, NetIQ
Corporation on www.netiq.com.
20ms or less
50ms or less
100ms or less
200ms or less
Jitter
2
20ms or less
50ms or less
50ms or less
50ms or less
(-10 ms ~ +10ms) (-25ms ~ +25ms) (-25ms ~ +25ms)
(-25ms ~ +25ms)
Packet loss
2
1×10
-3
or less
1×10
-3
or less
1×10
-3
or less
1×10
-3
or less
Packet error
2
1×10
-4
or less
1×10
-4
or less
1×10
-4
or less
1×10
-4
or less
Speech quality dependency on
CODEC parameters
Speech quality as the combination of the above network environment and the
CODEC parameters.
CODEC and
packet interval
in ms
Bandwidth per
channel (Single
direction, control
channel included)
G.711 at 20ms i
Prg 250-07
Prg 152-01
88kbps
3
3. Use this number to estimate the bandwidth needed for the CODEC and IP headers required to achieve an expected
Quality of Service (Excellent, Good, etc.). When planning you should allow extra bandwidth, especially when mixing
voice and data.
Excellent
Good
Fair
Poor
G.711 at 40ms i
Prg 250-07
Prg 152-01
76kbps
3
Excellent
Good
Fair
Poor
G.729A at 40ms
Prg 250-07
Prg 152-01
20kbps
3
Good
Good
Fair
Poor
G.729A at 80ms
Prg 250-07
Prg 152-01
14kbps
3
Good
Fair
Poor
Poor
