The main reason appears to be switch consolidation, as the one segment of the market that's still growing and predicted to grow further in 2011 is the top-of-rack (ToR) switch--a device that sits atop a server rack, consolidating all the rack's network links into just one or two. Dell'Oro predicts that the market for ToR switches will exceed $1 billion in 2011, an increase of more than 50% over 2010 as enterprises turn to network virtualization to cut costs and increase flexibility.
As in most other categories of Ethernet switching, the market leader in ToR switches is Cisco, which coincidentally also released a report Wednesday saying that Internet traffic was predicted to grow by 400% over the next four years. Compiled from data released by national governments and analyst firms such as IDC and Ovum, the Cisco Visual Networking Index (VNI) says that the bulk of the growth will be in consumer video, with more than a million minutes of video crossing the network every second. However, it also predicts an even larger role for the Internet in enterprise networking, as cloud computing makes business Internet traffic grow faster than the private IP links that currently link many enterprise networks together.
The Cisco and Dell'Oro reports aren't necessarily in conflict: Overall Internet traffic is growing, but switch capacity is growing even faster, so fewer switches are needed at the high end. At the low end, the move to Wi-Fi means that fewer Ethernet switch ports are needed to connect to client devices. The Cisco report predicts that by 2015, more Internet traffic will be destined for wireless than wired clients, despite each wired Ethernet link being able to offer more bandwidth than each wireless link. It says that the highest growth of all will be in nontraditional devices that will typically connect over a 3G or 4G mobile network.
In the data center, the business case for ToR switching is compelling. In recent months, vendors, including Force10, HP, Juniper, and Extreme, have launched or upgraded their ToR platforms, with most offering support for aggregating connections into 10 Gbps Ethernet and 40 Gbps Ethernet cables that can each run thousands of virtual Ethernet or Fibre Channel links. According to Dell'Oro, the biggest growth will be in 10-Gbps Ethernet ToR ports, as many racks still don't need the power of 40-Gbps Ethernet. Aggregating multiple gigabit Ethernet links can save on power and simplify management, while also reducing the need for further switches deeper in the network.
The switch to ToR could mean a shakeup among vendors. Although Cisco leads both the overall and the ToR switching markets, Dell'Oro says Cisco in the ToR switching is followed by Arista and IBM, whereas in overall Layer2 and Layer 3 Ethernet switching it is followed by HP, Dell, Juniper, and Brocade.
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