Smart link is a switch feature that provides effective, simple and fast-converging link redundancy in network topology with dual uplink between different layers of the network. It requires an active (master) and a backup (slave) link. The active link carries the uplink traffic. Upon failure of the active link, a switchover is triggered and the traffic is directed to the backup link.
-
In the previous figure, 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.
Use the following commands to configure Smart link:
-
Create a smart link group, using optional parameters as necessary:
Options
NOTE: When executed without any parameters, this command enters into Smart link group context.
-
Configure VLANs to receive flush messages. This is an interface level command. It must be executed for both the master and the slave port.
The following example illustrates Smart link configuration with VLAN load-balancing:
-
vlans 1-10 mapped to smart-link group 1:
HP-Switch(config)#smart-link group 1 master a1 slave a2 HP-Switch(config)#smart-link group 1 protected-vlans 1-10 HP-Switch(config)#smart-link group 1 send-control-vlan 1 HP-Switch(config)#smart-link group 1 preemption-mode role HP-Switch(config)#smart-link group 1 preemption-delay 10
-
vlans 11-20 mapped to smart-link group 2:
HP-Switch(config)#smart-link group 2 master a2 slave a1 HP-Switch(config)#smart-link group 2 protected-vlans 11-20 HP-Switch(config)#smart-link group 2 send-control-vlan 10 HP-Switch(config)#smart-link group 2 preemption-mode role HP-Switch(config)#smart-link group 2 preemption-delay 15