Nortel Networks NN43001-563 - Manual (Page 45)

IP trunk card description 45
Follower cards continuously send Update messages to the Active Leader
card. These messages inform the Active Leader card of the Followers’ most
recent status and resources. The Active Leader sends Update messages
to the Follower cards, informing them of the updated dialing number to IP
address translation information. Also the Active Leader card continuously
sends messages about changes in the network performance of each
destination node in the dialing plan.
If a Follower card fails (for example, DSP failure), it reports to the Active
Leader that its failed resources are not available. The trunk ports involved
are considered faulty and appear busy to the Meridian 1/CS 1000M. Call
processing is maintained on the remaining IP Trunk 3.01 (and later) trunks.
If a Follower card loses communication with the Active Leader, all its ports
appear busy to the Meridian 1/CS 1000M. Alarms are raised by sending an
Simple Network Management Protocol (SNMP) trap to the IP addresses
in the SNMP manager list.
Active Leader and Backup Leader interaction
When a Leader card reboots into service, it sends bootp requests to
check whether an Active Leader card is present. If it receives a bootp
response, this indicates the presence of an Active Leader card and the
rebooting Leader becomes the Backup Leader. If it does not receive a bootp
response, this indicates the absence of an Active Leader and the rebooting
Leader becomes the Active Leader.
The Backup Leader monitors the heartbeat of the Active Leader by pinging
the Active Leader’s Node IP. In the event of the Active Leader’s failure (that
is, the Active Leader is not responding to the pinging of the Node IP address
by the Backup Leader), the Backup Leader takes over the Active Leader
role, in order to avoid service interruption. The Backup Leader assigns
the Node IP to its voice interface and announces its new status to all the
Follower cards. The Followers re-register with the new Active Leader and,
as a result, a new Resource Table is built immediately.
The Leader 0 and Leader 1 cards keep their node properties synchronized.
The Backup Leader receives a copy of the bootp.1 file, containing the bootp
table, from the Active Leader on bootup and when Node Properties are
downloaded to the Active Leader.
Critical synchronized data includes the following:
• the card index:
— index 1 indicates Leader 0
— index 2 indicates Leader 1
— index 3 or greater indicates Follower
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.