1-3For more information about STP and RRPP, refer to MSTP Configuration in the Access Volume andRRPP Configuration in the High Availability Volum.Smart Link is a feature developed to address the slow convergence issue with STP. It provides linkredundancy as well as fast convergence in a dual uplink network, allowing the backup link to take overquickly when the primary link fails. To sum up, Smart Link features the following:z Dedicated to dual uplink networksz Subsecond convergencez Easy to configureTerminologySmart link groupA smart link group consists of only two member ports: the master and the slave. At a time, only one portis active for forwarding, and the other port is blocked, that is, in the standby state. When link failureoccurs on the active port due to port shutdown or presence of unidirectional link for example, thestandby port becomes active to take over while the original active port transits to the blocked state.As shown in Figure 1-1, GE1/0/1 and GE1/0/2 of Device C and GE1/0/1 and GE1/0/2 of Device D eachform a smart link group, with GE1/0/1 being active and GE1/0/2 being standby.Master/slave portMaster port and slave port are two port roles in a smart link group. When both ports in a smart link groupare up, the master port preferentially transits to the forwarding state, while the slave port stays in thestandby state. Once the master port fails, the slave port takes over to forward traffic.As shown in Figure 1-1, you can configure GE1/0/1 of Device C and that of Device D as master ports,and GE1/0/2 of Device C and that of Device D slave ports.Master/slave linkThe link that connects the master port in a smart link group is the master link; the link that connects theslave port is the slave link.Protected VLANA smart link group controls the forwarding state of some data VLANs, which are referred to as protectedVLANs. Different smart link groups on a port control different protected VLANs. The state of the port in aprotected VLAN is determined by the state of the port in the smart link group.Transmit control VLANThe transmit control VLAN is used for transmitting flush messages. When link switchover occurs, thedevices (such as Device C and Device D in Figure 1-1) broadcast flush messages within the transmitcontrol VLAN.
