Nortel 1000 Description, Installation And Operation Manual page 156

Page 156 of 644
553-3001-363 Standard 2.00
ITG engineering guidelines
When tromboning of IP Trunks occurs due to limited TAT operation with
CS 1000 Release 2.0 and BCM 3.5, BCM and IP Peer use H.245 signaling to
the IP Trunk 3.01 (and later) node to establish a direct media path between
the two tromboned IP Trunks. There are three cases of direct media path
connection between two tromboned IP Trunks (trunk channels) when
interoperating with BCM and IP Peer:
• Both IP Trunks are on the same Media Card 32-port trunk card running
IP Trunk 3.01 (and later).
The circuit-switched path between the tromboned trunks is connected by
the time switch on the Media Card 32-port trunk card. There is no voice
quality degradation due to delay or multiple transcoding since the speech
path does not pass through the IP Trunk codecs and
packetization/depacketization. The tromboned trunks are busy for the
duration of the call.
• Both IP Trunks are on the same ITG-Pentium 24-port trunk card running
IP Trunk 3.01 (and later).
The media path between the tromboned trunks is connected by the IP
loopback route on the ITG-Pentium 24-port trunk card. Voice quality
degradation may occur due to delay and multiple transcoding since the
speech path passes through both codecs and
packetization/depacketization. The tromboned trunks are busy for the
duration of the call.
• The two IP Trunks are on different IP Trunk cards.
The media path between the tromboned trunks is connected by the TLAN
IP route between the two IP Trunk cards. Voice quality degradation may
occur due to delay and multiple transcoding since the speech path passes
through both codecs and packetization/depacketization. The tromboned
trunks are busy for the duration of the call.
TAT as a method of Improving Voice Quality in a VoIP network
In a purely TDM network, TAT provides a method of eliminating the
unnecessary use of trunking resources.
September 2004