Nortel ISDN Signaling Link, Description, Installation And Operation

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Page 30 of 378 Description
553-3001-202 Standard 1.00 April 2000
Active Leader
The Active Leader card is an ITG ISL Trunk card that acts as a point of
contact for all other Meridian 1 in the network.
The Active Leader card is responsible for the following:
• distribute incoming H.323 calls to each registered Follower card in its
node, and balance load among the registered cards for incoming IP calls
• IP addresses for other cards in its node
• work as a time server for all ITG ISL Trunk cards in its node
• perform network monitoring for outgoing calls in its node
• voice processing
All calls from a remote Meridian 1 ITG node are presented to the Active
Leader card. The Leader card maintains a resource table of all the ITG ISL
Trunk cards in its node. The Active Leader card consults its internal Follower
card resource table to determine which Follower card has the most idle
channels. The Active Leader card selects this card to receive the new call. The
Active Leader sends a message to the selected Follower card, informing it to
reserve a channel for the new call. It redirects the call to the selected Follower.
The Follower card performs dialed number to IP address translation.
Backup Leader
The Backup Leader card steps in when the Leader is out-of-service. This
minimizes service interruptions.
D-channel IP gateway (DCHIP)
The ITG ISL Trunk card with DCHIP functionality (DCHIP Card) is
connected by the RS-422 cable to the Multi-purpose Serial Data Link
(MSDL) card on the Meridian 1 large systems. It connects to the SDI/DCH
Card on small systems. The DCHIP Card is equipped with a DCH PC Card.
The DCH PC Card provides the RS-422 and LAPD functionality that is
required for the D-channel (DCH) interface to the Meridian 1. The DCHIP
Card is the network side of the Meridian 1 ISL D-channel connection. The
card is a tandem node in the switch network, providing a single-to multi-point
interface between the Meridian 1 and the IP network (see Figure 2).