I'm peaking in at Penny's invitation to tell you a little about Project Crossbow, an umbrella term for the features in the Solaris OS that implement network virtualization and resource control. Crossbow development is under way at the OpenSolaris Crossbow: Network Virtualization and Resource Control site. Using the Crossbow features, you can set up a "network-in-the-box" for a single system equipped with the latest GLDv3 interfaces, such as bge and xge. That single system could be as complex as a data center server equipped with multiple CPUs or as simple as your laptop.

So, what's in the network-in-the box?

The chief feature is the virtual NIC, or VNIC, a pseudo-interface configured on the system's physical interface. You can set up bandwidth management and flow control on each VNIC to greatly improve each physical interface's performance.

To isolate applications and further improve performance, you can create a "virtual network" for the system by configuring a container, such as IP Instances, zones, or xVM, on top of each VNIC. Standard tools such as ping and snoop can observe the doings on the individual containers. Finally, these containers can then exchange data without having to send their packet traffic over the external network. Instead, internal traffic is forwarded by Crossbow's virtual switch feature.

For more details, see Steffen Wieberle's Crossbow FAQ, which covers the basics about IP Instances, VNICs, and flow control Crossbow style. If you want the full technical scoop, the Crossbow Documentation page hosts the latest design docs, such as "Crossbow Hardware Resources Management and Virtualization" by Kais Belgaied and Roamer Lu, and "Crossbow Virtualization Architecture" by Nicolas Droux.

If you are new to the concept of network virtualization and want to learn more, I humbly present my Wikipedia article, Network Virtualization, a survey overview of the topic.