I am attempting to give a high level overview of Nortel/Avaya link aggregation techniques , some reputed proprietary protocols for someone who is new to Nortel/Avaya.
MultiLink Trunking (MLT):
MultiLink Trunking (MLT) is a point-to-point connection that aggregates multiple ports to logically act like a single port, with the aggregated bandwidth. It’s a link aggregation protocol similar to IEEE LACP or Cisco’s Ether channel.
Grouping multiple ports into a logical link provides a higher aggregate on a switch-to-switch or switch-to-server application.
Distributed MultiLink Trunking (DMLT):
MLT provides module redundancy via Distributed MultiLink Trunking (DMLT).
DMLT allows you to aggregate similar ports from different modules. Nortel recommends always using DMLT when possible.
To include ports as trunk group members of an MLT, you must statically configure the ports
Split MultiLink Trunking (SMLT):
SMLT is a Nortel/Avaya proprietary form of link aggregation that provides a way to combine two switches into one logical device for L2 networking. SMLT connects a MultiLink Trunking (MLT) switch to a pair of SMLT switches. This is similar to Cisco’s virtual Port Channel (vPC).
In SMLT, two core switches are connected by an Inter-Switch Trunk (IST). The two core switches use the IST to share L2 learned information, so they appear as one. The designated IST “control” VLAN implements a specialized control protocol that encapsulates the update in IP so that forwarding databases (FDB) in both switches are synchronized.
SMLT eliminates the need for Spanning Tree protocol and its complexity.
Single Link Trunking (SLT):
SLT is a port-based option of SMLT where only one port from each core switch is used in the SMLT. The only difference between SMLT and SLT is in SLT only single port from each core switch will participate in the aggregation.
SLT is best suited for large-scale deployments of edge switches from a single switch cluster.
Routed Split MultiLink Trunking (RSMLT):
SMLT is a way to ensure that traffic gets across a VLAN by providing redundant switches and redundant links whereas RSMLT ensures traffic can be routed off the VLAN by adding router redundancy. RSMLT is similar to VRRP and provides the same services as VRRP but it is Nortel/Avaya proprietary.