Page 76 of 378 ITG Engineering Guidelines
553-3001-202 Standard 1.00 April 2000
ITG traffic engineering
To design a network is to size the network so that it can accept some
calculated amount of traffic. The purpose of the ITG network is to deliver
voice traffic meeting the QoS objectives. Since traffic determines network
design, the design process needs to start with the process of obtaining offered
ITG traffic forecast. The traffic forecast will drive:
• WAN requirements
• ITG hardware requirements
• T-LAN require m ents

Use of Ethernet and WAN bandwidth

Table 5 on page 77 lists the Ethernet and WAN bandwidth use of ITG ports
with different codecs with silence suppression enabled, and Table 6 on
page 80 lists the use with silence su ppression disabled. One port is a c hannel
fully loaded to 36 CCS, w h er e o ne CC S (C e nt i -C all-Second) is a
channel/circuit being occupied 100 seconds . 36 CCS is a c ir cuit oc cupie d for
a full hour. To calculate the bandwidth requirement of a rout e, the total rou te
traffic should be divided by 36 CCS and multiplied by the ban dwidth use to
get the data rate requirement of that route. All traffic data must be based on
the busy hour of the busy day.
Note that to calculate resource requirements (ITG ports and T-LAN/WAN
bandwidth), traffic parcels are summarized in different ways:
1Add all sources of traffic for the ITG network, e.g., voice, fax sent, fax
received, together to calculate ITG port and T-LAN requirements.
2For data rate requirement at each route, the calcu lation is based on each
destination pair.
3For fax traffic on a WAN, only the larger of either the fax-sent or
fax-received traff ic is to be accoun ted for.
The engineering procedures for T-LAN and WAN are different. The
following calculation procedure is for T-LAN (the modification required for
WAN engineering is included in these procedures).