The Nexus 1000v is a VDS for vmware and is limited by the abilities of vmware. It cannot span multiple datacenter containers within vCenter (it can span multiple phsyical data center defined as one datacenter within vCenter).
VMware® vNetwork Distributed Switch:
Migration and Con guration
http://www.vmware.com/files/pdf/vsphere-vnetwork-ds-migration-configuration-wp.pdf
What is a vNetwork Distributed Switch?
A vNetwork Distributed Switch is an aggregation of per-host virtual switches presented and controlled as a single distributed switch through vCenter Server at the Datacenter level. The vDS abstracts configuration of individual virtual switches and enables centralized provisioning, administration, and monitoring.
Configuration Considerations for the vNetwork Distributed Switch
The vDS follows many of the same configuration conventions and rules as the vNetwork Standard Switch. A vDS can span multiple hosts within a vCenter Server Datacenter construct.
