Alcatel-Lucent OmniSwitch AOS Release 7 - Topologies Not Recommended; Unsupported Topologies

Configuring Multi-chassis Link Aggregation MC-LAG Topologies
OmniSwitch AOS Release 7 Network Configuration Guide March 2011 page 8-15
Topologies Not Recommended
In the topology shown below, edge devices are not attached to both MC-LAG peers at the core. As a
result, some traffic may need to constantly flow across the Virtual Fabric Link. Still, Spanning Tree is not
required as there are no logical loops in this network.
Edge Switches Without MC-LAG
Unsupported Topologies
In the topology shown below, MC-LAG is not supported since Spanning Tree cannot run with a “back-
door” connection and will result in a loop.
Back-door Connection Causing Physical Loop
MC-LAG
MC-LAG
MC-LAG MC-LAG
L2 Bridging
LAG
Ordinary
aggregate, i.e.
non-MC-LAG
MC-LAG
MC-LAG
MC-LAG
LAG
Spanning tree cannot
run on the dual-
homed aggregates.