Nortel Networks NN43001-563 - Manual (Page 119)

Factors that effect the real-time capacity 119
TRO functions in a different manner than TAT. TRO is invoked before the call
has been answered. TAT is invoked once the call has been answered. To
reduce the number of trunks being used due to call redirection by CFNA,
Hunt, or Forward all Calls, configure TRO in the RDB. TRO must be enabled
at all sites.
If Telephone A at Site 1 calls Telephone B at Site 2, and Telephone B
forwards a call using CFNA to Telephone C at Site 3, then TRO must be
enabled at Sites 1 and 2. If TRO is enabled at both sites, Site 2 will drop
out, freeing up the trunk, and only trunks on Site 1 and 3 are used. This
reduces the number of trunks in use, conserves bandwidth, and improves
voice quality.
The TRMB prompt in RDB does not have to be set to Yes for TAT or TRO to
work. The function of the TRMB prompt is to allow or disallow tromboning
caused by NARS/BARS mis-configuration. For example, Site A has DSC of
4000 pointing to Site B. Site B has DSC of 4000 pointing back to Site A. If a
caller at Site A dials 4000, this can lead to the call orbiting between the two
sites. This is commonly referred to as the "Ping-Pong" effect. Therefore,
Nortel recommends setting TRMB to NO.
WAN route bandwidth engineering
After the TLAN subnet traffic is calculated, determine the bandwidth
requirement for the WAN. In this environment, bandwidth calculation is
based on network topology and destination pairs.
Before network engineering can begin, obtain the following network data:
• A network topology and routing diagram.
• A list of the sites where the IP Trunk 3.01 (and later) nodes are to be
installed.
• List the sites with IP Trunk 3.01 (and later) traffic, and the codec and
frame duration (payload) to be used.
• Obtain the offered traffic in CCS for each site pair; if available, separate
voice traffic from fax traffic (fax traffic sent and received).
• In a network with multiple time zones, use the same real-time busy hour
varying clock hours) at each site that yields the highest overall network
traffic. Traffic to a route is the sum of voice traffic plus the larger of one
way fax traffic (either sent or received.
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.