KB.15.15

• In the figure above, ports A1 and A2 are configured as part of a Smart link group. The

connection from the access switch to Distribution Switch A is the master, and the connection

from the access switch to Distribution Switch B is the slave.

• Only the master interface forwards traffic for a group of vlans (referred to as protected vlan

group).

• The other interface is in standby mode for this protected group. If port A1 goes down, port

A2 starts forwarding traffic for this protected vlan group.

• If port A1 comes back up, it goes to standby mode and does not forward traffic. Port A2

continues forwarding traffic. This is the case if preemption-mode is configured as “role”.

If preemption-mode is not configured as “role”, when the master (A1) comes back up, it

becomes Active (forwarding) after the configured ‘preemption-delay’.

• Since a Smart link group has the information readily available via configuration as to which

port should be forwarding for the protected vlan group in the case of the active link failure,

the failover is much quicker when compared with STP.

Overview 377