Nortel SMC 2450, Руководство по внедрению

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Description Page 47 of 260
Secure Multimedia Controller Implementation Guide
requires the client to re-establish the connection using the TCP handshake;
however, the client takes 15 minutes to recognize that the session is down and
re-establish connectivity.
You can use the Port Bypass feature to guard against this downtime by
allowing the session traffic through.
Note: During port bypass, the traffic is not protected by the SMC.
SMC resiliency scenario
The SMC, as a proxy for the UNIStim signaling server, provides a failover
scenario that is similar to that of a signaling server. For more information, see
the
Communication Server 1000M and Meridian 1: Small System Planning
and Engineering (553-3011-120).
When the master SMC fails, the IP phones lose signaling connectivity and
re-register to the backup SMC. In secure mode, this registration can use
session cache synchronization to lessen the resource utilization of many IP
phones simultaneously re-registering.
In this scenario, an IP Phone 2004 is using a Signaling Server proxied by the
SMC. A high availability SMC configuration is present. The master SMC
goes down and fails over to the backup SMC. The current signaling session
is interrupted and fails.
The treatment of the call in progress depends on the type of call:
• Intranet phone to intranet phone
• Intranet phone to phone in the SMZ
Although the treatment of the call in progress is different, note that the end
result is the same: the call is dropped.
Intranet phone to intranet phone
In an intranet phone to intranet phone call, the media does not cross the SMC.
The phone attempts to re-establish signaling communication with the
signaling server. During this time, the call is dropped. The phone creates a
new secure signaling channel.