Managing SMLT configurations

Mission critical networks require resiliency, and as a result, must be designed with a number of redundancy features. Within the Passport 8000 Series switch, such features include CPU redundancy and link redundancy using MLT.

In order to provide device redundancy, most enterprise networks are designed with redundant connections between aggregation (core) switches and user access switches. For networks with just one aggregation switch, MLT provides redundancy and load sharing.

SMLT improves the reliability of a layer 2 (L2) network operating between a building's user access switches and the network center aggregation switch. It does so by providing loadsharing among all the links and fast failover in case of link failures.

An Inter Switch Trunk (IST) operates between the aggregation switches and allows them to exchange information. This permits the rapid detection of any faults and the modification of forwarding paths.

Note: Although SMLT is primarily designed for layer 2 networks, it also provides benefits for layer 3 networks as well.

For more information about SMLT, see Networking Concepts for the Passport 8000 Series Switch.

To configure SMLT, you must establish three sets of configurations on the devices:

On the two peer aggregation switches, you configure an IST (inter-switch trunk). For more information, see Configuring IST links.
On the two peer aggregation switches, you configure SMLT links to the edge switch. For more information, see Configuring SMLT links on peer devices.
On the non-peer device, you configure normal MLT links to the two peer devices. For more information, see Configuring SMLT links on non-peer devices.
On the two peer devices, you configure the IST peers. For more information, see Configuring IST peers.

The following figure shows a typical triangle SMLT configuration.