Split Multi-Link Trunking

Split Multi-Link Trunking ( SMLT ) is an introduced by Nortel Networks in 2001, expansion of the described in the IEEE 802.3ad standard Multi-Link Trunking Protocol ( MLT) in computer networks. The extension was proposed by Nortel of the IEEE supplementing in the IEEE 802 standard.

Link aggregation or the Multi-Link Trunking have the advantage that they allow multiple physical connections in a computer network between two network switches and their peers and treated as a logical connection. Thus they allow the distribution of network load between the available connections and provide a network path with greater bandwidth than that which can be achieved with a simple network connection (link). The other bodies referred to other network switches or network be connected equipment, such as servers.

In general, the normal link aggregation, the MLT and the Etherchannel technique is limited to the fact that all physical network interfaces (ports), for example, a link aggregation must be connected to one side of the network to the same switch. The designed Nortel SMLT protocols, DSMLT and RSMLT lift this restriction and allow the physical connections on two network switches to be distributed to a network page.

The Split Multi- Link Aggregation thereby allows the use of normally by the Spanning Tree Protocol ligated multiple connections within an Ethernet network. Thus an active load sharing and the establishment of a high availability network with an availability of 99.999 % is possible.

For each upcoming data packet for transmission (link ) is selected based on a load balancing algorithm one of the available physical transmission paths, usually a hash function on the Media Access Control (MAC ) address is applied to the source and destination device. Under normal network traffic, this usually leads to an effective bandwidth of the logical link that corresponds to the sum of the bandwidths of the individual physical links. So far, a multiple ( loop, loop) was prevented between different network segments by the Spanning Tree Protocol. The so for safety's sake incurred redundant connections can now be exploited to its full capacity with SMLT.

The protocol is protected under U.S. Patent 7173934; with the purchase of Nortel by Avaya in September 2009, Avaya was owner of the patent. Avaya provides switches that support SMLT.