Multi-Link Trunking (MLT) is a link aggregation

Link aggregation

Link aggregation or trunking or link bundling or Ethernet/network/NIC bonding or NIC teaming are computer networking umbrella terms to describe various methods of combining multiple network connections in parallel to increase throughput beyond what a single connection could sustain, and to provide...

 or IEEE 802.3ad port trunking

Trunking

In modern communications, trunking is a concept by which a communications system can provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually. This is analogous to the structure of a tree with one trunk and many branches. Examples of...

 technology designed by Nortel

Nortel

Nortel Networks Corporation, formerly known as Northern Telecom Limited and sometimes known simply as Nortel, was a multinational telecommunications equipment manufacturer headquartered in Mississauga, Ontario, Canada...

 (now Avaya

Avaya

Avaya Inc. is a privately held computer networking, information technology and telecommunications company that is a global provider of business communications systems. The international head quarters is in Basking Ridge, New Jersey, United States...

). It allows grouping several physical Ethernet

Ethernet

Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....

 links into one logical Ethernet link to provide fault-tolerance and high-speed links between routers, switches, and servers. In the past redundant links were unused due to Spanning Tree

Spanning tree protocol

The Spanning Tree Protocol is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network. The basic function of STP is to prevent bridge loops and ensuing broadcast radiation...

’s loop protection.

Using this technology allows or enables the use of several links (from 2 up to 8) and combined them to create increased bandwidth and several fail-over paths.