Port Redundancy; Port Redundancy Operation - Avaya P333T Installation & Configuration Manual

Chapter 11 Avaya P330 Layer 2 Features

Port Redundancy

Port redundancy involves the duplication of devices, services, or connections, so
that, in the event of a failure, the redundant device, service, or connection can take
over for the one that failed.
In addition to Link Aggregation Groups—which comprise the basic redundancy
mechanism within the switch—the P330 offers an additional port redundancy
scheme. To achieve port redundancy, you can define a redundancy relationship
between any two ports in a stack. One port is defined as the primary port and the
other as the secondary port. If the primary port fails, the secondary port takes over.
You can configure up to 20 pairs of ports (or LAGs) per stack for port redundancy,
and 1 pair per stack for intermodule redundancy. Each pair contains a primary and
secondary port. You can configure any type of port to be redundant to any other.

Port Redundancy Operation

The Port Redundancy feature supports up to 20 pairs of ports per stack. The
redundant or secondary port takes over when the primary port link is down. Port
redundancy provides for the following in the P330:
• Switchback from the secondary to primary port is allowed
• Switching time intervals can be set by the user
Note: Port Redundancy interworks with the Spnning Tree Algorithm.
The Port Redundancy feature functions as follows:
• Port Redundancy enables the user to establish 20 pairs of ports. Within each
pair, primary and secondary ports are defined. To prevent loops, only one port
is enabled at a time.
• Following initialization, the primary port is enabled and the secondary port is
disabled.
— If the active port link fails, the system enables the secondary port.
— If the secondary port is enabled and the primary port link becomes
available again, the system will "switchback" to the primary port, unless
configured otherwise by the user.
• Two timers are available:
— "min-time-between-switchovers" —minimum time (in seconds) between
the failure of the primary port link and switchover to the secondary
(backup) port.
Note: The first time the primary port fails, the switchover is immediate. This timer
applies to subsequent failures.
80 Avaya P333T User's Guide