IP Telephony network engineering overview
280 Avaya Application Solutions IP Telephony Deployment Guide
The critical objective factors in assessing IP Telephony quality are delay, jitter, and packet loss.
To ensure good and consistent levels of voice quality,
Table 66: Factors that affect voice quality
lists Avaya’s suggested network requirements. These requirements are true for both LAN only
and for LAN and WAN connections.
For more information see
Voice quality network requirements
.
Table 66: Factors that affect voice quality
Network factor
Measurement
1
1. All measurement values are between endpoints because this document assumes that IP Telephony is
not yet implemented. All values therefore reflect the performance of the network without endpoint
consideration.
Delay
(one-way between
endpoints)
●
A delay of 80 ms or less can, but may not, yield the best
quality.
●
A delay of 80 ms to 180 ms can yield
business-communication quality. Business-communication
quality is much better than cell-phone quality, and is
well-suited for the majority of businesses.
2
●
Delays that exceed 180 ms might still be quite acceptable
depending on customer expectations, analog trunks used,
codec type, and so on.
2. Also, “business-communication quality” is defined as less than toll quality, but much better than
cell-phone quality.
Jitter
(variability of the delay
between endpoints)
●
20 ms, or less than half the sample size, for the best quality.
Note:
Note:
This value has some latitude, depending on the
type of service that the jitter buffer has in
relationship to other router buffers, the packet size
used, and so on.
Packet loss
(maximum packet/
frame loss between
endpoints)
●
<1% can yield the best quality, depending on many factors.
●
<3% should give business-communications quality, which is
much better than cell-phone quality.
2
●
>3% might be acceptable for voice, but might interfere with
signaling.
Summary of Contents for Application Solutions
Page 1: ...Avaya Application Solutions IP Telephony Deployment Guide 555 245 600 Issue 3 4 1 June 2005 ...
Page 20: ...About This Book 20 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 21: ...Issue 3 4 1 June 2005 21 Section 1 Avaya Application Solutions product guide ...
Page 22: ...22 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 106: ...Call processing 106 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 124: ...Avaya LAN switching products 124 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 139: ...Issue 3 4 1 June 2005 139 Section 2 Deploying IP Telephony ...
Page 140: ...140 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 186: ...Traffic engineering 186 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 204: ...Security 204 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 228: ...Avaya Integrated Management 228 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 274: ...Reliability and Recovery 274 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 275: ...Issue 3 4 1 June 2005 275 Section 3 Getting the IP network ready for telephony ...
Page 276: ...276 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 356: ...Network recovery 356 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 366: ...Network assessment offer 366 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 367: ...Issue 3 4 1 June 2005 367 Appendixes ...
Page 368: ...Appendixes 368 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 394: ...Access list 394 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 414: ...DHCP TFTP 414 Avaya Application Solutions IP Telephony Deployment Guide ...