Topology for Distributed Ethernet Fabrics using vLAG
When a port-channel from a node in one VCS spans across multiple RBridges in other VCS cluster, a vLAG is formed on the RBridges in the VCS cluster that are part of the same port-channel. For Distributed Ethernet Fabrics using vLAG over long distances, only LACP-based standard port-channels are supported. For details on how to create port-channels and vLAGs, refer to Configuring Link Aggregation in the Layer 2 Switching Configuration Guide.
The following figure is a typical deployment topology that uses distributed Ethernet Fabrics using vLAG to interconnect data centers. Nodes from the local VCS cluster are connected by means of xWDM to the nodes in a distant VCS clusters to form a vLAG in between. The distant VCS cluster can be a standard VCS cluster or could be spanned across two data centers over standard-distance or long-distance ISLs, as shown in the figure below. In this case, the vLAG between the two data centers provides VCS fabric isolation while providing seamless Layer 2 connectivity.