Quality of Service guidelines
314 Avaya Application Solutions IP Telephony Deployment Guide
serialization delay for a variety of packet sizes and line speeds. The formula for determining
serialization delay is:
Because of all these configuration variables, properly implementing QoS on a router is no trivial
task. However, QoS is needed most on the router where, because most WAN circuits terminate
on routers.
QoS guidelines
There is no all-inclusive rule regarding the implementation of QoS because all networks and
their traffic characteristics are unique. It is good practice to baseline the IP Telephony response
on a network without QoS, and then apply QoS as necessary. Avaya Network Consulting
Services can help with baselining services. Conversely, it is bad practice to enable multiple QoS
features simultaneously, not knowing what effects, if any, each feature is introducing.
Generally, for newer network equipment, best practices involve enabling Layer 3 (DiffServ) QoS
on WAN links traversed by voice. Tag voice and data with DiffServ Code Point 46 (Expedited
Forwarding), and set up a strict priority queue for voice. If voice quality is still not acceptable, or
if QoS is desired for contingencies such as unexpected traffic storms, QoS can then be
implemented on the LAN segments as necessary.
Table 72: Serialization delay matrix
WAN
line
speed
Packet size
64
bytes
128
bytes
256
bytes
512
bytes
1024
bytes
1500
bytes
56 kbps
9 ms
18 ms
36 ms
72 ms
144 ms
214 ms
64 kbps
8 ms
16 ms
32 ms
64 ms
128 ms
187 ms
128 kbps
4 ms
8 ms
16 ms
32 ms
64 ms
93 ms
256 kbps
2 ms
4 ms
8 ms
16 ms
32 ms
46 ms
512 kbps
1 ms
2 ms
4 ms
8 ms
16 ms
23 ms
768 kbps
640 µs
1.28 ms
2.56 ms
5.12 ms
10.24 ms
15 ms
Serialization delay
Packet size (bits)
Line speed
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Содержание Application Solutions
Страница 1: ...Avaya Application Solutions IP Telephony Deployment Guide 555 245 600 Issue 3 4 1 June 2005 ...
Страница 20: ...About This Book 20 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 21: ...Issue 3 4 1 June 2005 21 Section 1 Avaya Application Solutions product guide ...
Страница 22: ...22 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 74: ...Avaya Application Solutions platforms 74 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 106: ...Call processing 106 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 124: ...Avaya LAN switching products 124 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 139: ...Issue 3 4 1 June 2005 139 Section 2 Deploying IP Telephony ...
Страница 140: ...140 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 186: ...Traffic engineering 186 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 204: ...Security 204 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 214: ...Voice quality network requirements 214 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 228: ...Avaya Integrated Management 228 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 239: ...Reliability Issue 3 4 1 June 2005 239 Figure 69 S8700 Media Server in a high reliability configuration ...
Страница 274: ...Reliability and Recovery 274 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 275: ...Issue 3 4 1 June 2005 275 Section 3 Getting the IP network ready for telephony ...
Страница 276: ...276 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 350: ...Implementing Communication Manager on a data network 350 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 356: ...Network recovery 356 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 366: ...Network assessment offer 366 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 367: ...Issue 3 4 1 June 2005 367 Appendixes ...
Страница 368: ...Appendixes 368 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 394: ...Access list 394 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 414: ...DHCP TFTP 414 Avaya Application Solutions IP Telephony Deployment Guide ...