Nortel ISDN Signaling Link, Описание, установка и эксплуатация

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ITG Engineering Guidelines Page 109 of 378
ITG Trunk 2.0 ISDN Signaling Link (ISL) Description, Installation and Operation
• The Meridian 1 (including the ITG nodes) interfaces with the end users;
voice services offered by the Meridian 1 need to meet user-oriented QoS
objectives.
• The ITG nodes interface with the intranet; the service provided by the
intranet is “best-effort delivery of IP packets”, not “guarantee QoS for
real-time voice transport.” The ITG translates the QoS objectives set by
the end-users into IP-oriented QoS objectives. The guidelines call these
objectives intranet QoS objectives.
Figure 14
Relationship between users and services
Corporate intranet
Meridian 1
ITG
Deliver IP service
Deliver voice/fax
service
- Fall back threshold
- Codec
- Payload size
ITG parameters
User oriented QOS
- Roundtrip conversation delay
- Clipping and dropout
- Audio level
- Echo Network QOS metrics
- One way delay
- Packet loss
- Silence suppression threshold
- Echo cancellor tail delay size
- Audio gain
Delay variation
- Jitter
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