Effects of virtualization and cloud computing on data center networks

Figure 6: VEPA sends all traffic to the adjacent physical switch.

Advantages of VEPA include:

• Moves the VM connection control point into the edge physical switch (ToR or EoR). VEPA leverages

existing investments made in data center edge switching. Administrators can manage the edge

network traffic using existing network security policies and tools.

• Offloads the server’s CPU from the overhead related to virtualization specific network processing

and forwarding

• Improves security. Most ToR switches support hardware-based access control lists (TCAMs),

allowing thousands of these filters to be processed without any effect on performance.

• Improves visibility. Monitoring technologies like sFlow in the edge switch can provide a full, end-to-

end understanding of traffic flows.

If you plan to implement VEPA technology in the future, you can get the advantages of high-

performance E/W traffic across physical servers and management visibility at the physical server-

network edge. But it doesn’t give you advantages with E/W traffic within a single virtualized server.

The EVB standard supports VEPA-based switches and existing vSwitch (VEB) architectures

simultaneously (Figure 7). IT architects can choose whether to manage the edge traffic (frame

processing, security features, networking monitoring, and so on) in the local hypervisor (vSwitch) or in

the adjacent physical switch (VEPA-based switch).

EVB

L2 net(s)

Physical NIC

Virtual NIC

External Network

Physical Server

VM Edge Switch Edge

Server Edge