Resource sizing
Issue 3.4.1 June 2005
183
used) implies a total overhead of 11 bytes (88 bits) in this example. This implies the following
table of WAN bandwidths,
Table 39: IP WAN bandwidth requirements for media streams
, which
assumes the use of cRTP:
This table can be used in the WAN bandwidth calculation for the system in
Example 6: IP
bandwidth considerations
.
Example 8: WAN bandwidth
In
Example 6: IP bandwidth considerations
, the total IP WAN bandwidth usage between each
pair of sites was calculated, and expressed in Erlangs at the bottom of
Table 35: IP WAN
bandwidth usages (Erlangs) for Example 6: IP bandwidth considerations
on page 179.
Specifically, the total WAN bandwidth usage between Sites 1 and 2 is 24.0 Erlangs, between
Sites 1 and 3 is 10.0 Erlangs, and between Sites 2 and 3 is 4.0 Erlangs. This implies that the
average number of media streams simultaneously in use at any given time between Sites 1 and
2 is 24. Analogous statements can also be made regarding WAN traffic between each of the
other two pairs of sites.
Every media stream across the IP WAN, between any pair of sites, is assumed to use the
compressed G.729 codec, since bandwidth is relatively inexpensive within a private LAN, as
opposed to a public WAN. Assume, for the sake of this example, a standard IP packet size of 20
ms. For the G.729 codec,
Table 39: IP WAN bandwidth requirements for media streams
on
page 183 indicates that each (unidirectional) media stream consumes 12.4 kbps of IP WAN
bandwidth. Similar to the case in
Example 7: LAN bandwidth
, 24 is the average number of
simultaneous bidirectional media streams. As in
Example 7: LAN bandwidth
, the bandwidth is
sized to a “GOS” of P001 (“GOS” in this context is actually a pseudo-GOS; true GOS is
associated with a fixed number of channels, as is typical of circuit-switched systems). The
standard infinite-server queueing model implies that less than 0.1% of the time there is at least
40 simultaneous media streams between Sites 1 and 2. So, it is sufficient to engineer the WAN
bandwidth between those two sites to support 39 simultaneous media streams. Therefore, the
WAN between Sites 1 and 2 requires at least (39 simultaneous media streams) x (12.4 kbps per
media stream) = 484 kbps of bandwidth. This result, along with the analogous results for the
WAN traffic between the other two pairs of sites, are provided in
Table 40: IP WAN bandwidth
requirements in each direction, for Example 8: WAN bandwidth
on page 184.
Table 39: IP WAN bandwidth requirements for media streams
Packet “size”
(ms)
G.711 (kbps)
G.729 (kbps)
10
72.8
16.8
20
68.4
12.4
30
66.9
10.9
60
65.5
9.5
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 ...