Multi-link trunking

The Multi-Link Trunking (MLT) is a link aggregation technology defined by the IEEE 802.3ad standard designed by Nortel. It allows the grouping of several physical Ethernet links on a single Ethernet logical link to provide fault tolerance and high-speed links between routers, switches and servers. Previously no redundant links were used because of the loop protection offered by the Spanning Tree Protocol.

The use of this technology allows the use of several links (between 2 and 8) combining them to increase the bandwidth and alternative paths of failure. This way you can create connections between a switch and a server or between switches up to 8 times faster.

Fault tolerance is a very important aspect of this technology. If one or more links fail, MLT technology automatically distributes traffic between the remaining links. Automatic redistribution occurs in less than half a second (typically less than 100 milliseconds) so users do not notice any cutoffs. This high-speed recovery is necessary in many critical networks where cuts can cause loss of life or large economic losses. The combination of MLT with DMLT, SMLT, DSMLT and RSMLT allows the creation of most critical networks.

One limitation of the MLT standard is that all physical ports in the link aggregation group have to be on the same switch. SMLT, DSMLT and RSMLT do not have this limitation allowing physical ports to be separated into different switches.

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