Nortel Networks NN43001-563

24 Overview of IP Trunk3.01

The ﬂag value is ignored when the provisioned Gatekeeper is a CS

1000M Gatekeeper.

On startup, if the IP Trunk3.01 (and later) Leader is provisioned to use a

Gatekeeper,it seeks out and locates the Gatekeeper using RAS signalling

and then registers with the Gatekeeper using an RRQ. As part of the

registration process, the IP Trunk3.01 (and later) Leader registers using the

registration handling ﬂag to determine how to proceed.

The Gatekeeper and IP Trunk3.01 (and later) re-register on a regular basis,

based on the Time ToLive (TTL) conﬁgured for the IP path.

The Gatekeeper is the ﬁnal authority on the TTL values. The Gatekeeper

can override the provisioned value of IP Trunk3.01 (and later) and require

the IP Trunk3.01 (and later) gateway to change its TTL value to match that

required by the Gatekeeper.

Depending on the Gatekeeper type (for example, Gatekeepersother than

CS 1000M), if the Gatekeeper ﬂag in the dial plan ﬁle indicates the need for

multiple IP Trunk3.01 card IP addresses (ﬂag value = 0), the RRQ includes

all IP addresses for the node. These additional IP addresses are reserved

exclusively forcalls to the Gatekeeper. By sending all the IP addresses in

the RRQ, the Gatekeeper is able to determine the origin of the admission

requests. These addresses are used when the Gatekeeper considers

the endpointIdentiﬁer sent to the gateway in the RRQ conﬁrmation to

be insufﬁcient to conﬁrm that the Admission Request (ARQ) belongs to a

gatewayregistered with that Gatekeeper. The Gatekeeper rejects any ARQ

from an unknown end-point.

CS 1000M requires an endpointIdentiﬁer match and does not care about

the IP addresses. Therefore, the Gatekeeper ﬂag is unnecessary for CS

1000M.

On startup, the message ﬂow between the IP trunk card serving as the IP

Trunk3.01 (and later) Active Leader and the Gatekeeper is as follows:

1. Gatekeeper Request (GRQ) – From the Active Leader to the

Gatekeeper,using the provisioned Gatekeeper IP address. The Optivity

TelephonyManager (TM 3.1) conﬁguration indicates where the IP

Trunk3.01 (and later) node must look for its Gatekeeper, but this is

not necessarily the actual Gatekeeper address the node uses for call

processing.

Some Gatekeepers use a "virtual IP address" to screen the fact that

the Gatekeeper with which the gateway registers has internal standby

controllers. In this case, the request might go to a Gatekeeper server

that determines the correct virtual IP address. The Gatekeeper’s

internal Message Forwarding process sends the messages to the

current active Gatekeeper node.

Nortel Communication Server 1000

IP TrunkFundamentals

NN43001-563 02.01 Standard

Release 5.5 21 December 2007