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What to consider when choosing the best Ethernet switch

IT pros need to consider new developments in technology like software-defined networking and the Internet of Things when choosing the best Ethernet switch for their current and future network.

The campus network environment is changing rapidly as the number of wireless-only users and networked devices continues to accelerate. At the same time, the advent of new technologies, such as software-defined networking (SDN), is dramatically changing the campus landscape.

Given that the switches deployed in any enterprise campus network tend to have longevity, IT staff will have important choices to make in the next few years as they determine which is the best Ethernet switch to buy for the next generation of network infrastructure.

How it works

Ethernet is the low-level protocol we use to move data around our wired networks; it dictates how we put data on the wire and how devices on the same segment of the network find and talk to each other.

When Ethernet was developed initially, it used long runs (loops) of coaxial cable to connect many devices to the network; each segment of the network had lots of devices on it, daisy-chained. Ethernet loops gave way to "star" networks: each device connected separately to a hub with a dedicated cable. Hubs took every packet of information they received on a port and repeated it out to all the other ports. Star networks made the wiring easier and the network more resilient: A cable break cut off only one device rather than all the devices on a loop.

As more and more devices crowded onto networks, Ethernet congestion became a bigger issue. Too many computers trying to talk at the same time caused unpredictable and highly variable network performance. This led to the creation of Ethernet switches. As with a hub, an Ethernet switch sits at the center of a star topology; but unlike a hub, it is selective about where it sends packets. Switches learn the physical (MAC) address of each device connected to them, and send each device only the packets directed to it. (Packets aimed at devices not connected to the switch get sent through its uplink for some other switch to deliver.) 

Network switch features

Switches made it possible to have multiple networked devices on every desk as well as bandwidth-intensive applications -- such as video conferencing -- that boast high rates of data transmission and no tolerance for congestion. They form the foundation of the modern wired network, providing the link through which computers, printers and other devices connect on the campus, as well as the data center edge to which servers and storage connect. In most campus and some data center networks, switches also provide the second layer of network function, the aggregation layer into which edge switches connect.

Given the Ethernet switch's criticality, pervasiveness and durability, those planning a switching refresh in their campus networks need to ensure that their next switches meet both their current and future requirements. With trends like SDN and the Internet of Things transforming the industry, enterprises have to be careful to get the features they need from this ubiquitous device -- today and tomorrow. Here's what to consider when trying to determine the best Ethernet switch for your system.

The Must-Have List

  • Speed: Most enterprises will be shifting to 1 Gbps on edge switch ports, even if they don't see a clear need for it on the desktop at the moment. They are buying for seven years of future shifts in network usage, after all. Full multiscreen streaming HDX VDI-driven video conferencing? They'll want to have it covered. Also, we're not just talking about computers and printers. We're talking about WLAN access points (APs) and enterprises needing additional throughput as wireless speeds continue to rise. (And, of course, IT has to make sure the cable plant is up to spec for 1000 Base-T. Hello, cable audit!)
  • Density:  If you haven't shifted to VoIP, and aren't ready to give up on hard phones, you'll probably want lots of ports to make the migration easy, so high port densities with low baseline power pulls will be ideal. And, along with VoIP, mobility and the Internet of Things (IoT) are going to drive up port consumption as well. The explosion of mobile devices and the ongoing shift to laptops on Wi-Fi feed into the emerging wireless-only lifestyle. All that spells higher-speed WLANs (802.11n and 802.11ac) with greater density of access points. More access points means more Ethernet ports; increasingly, it means multiple ports for each AP to deal with those speed increases on the WLAN. The IoT explosion of smart devices, ranging from networked thermostats to Internet-enabled vending machines, will also drive a need for more ports.
  • Power Over Ethernet: Port density is only part of what IT needs to evaluate. VoIP phones, WLAN APs and remote networked devices mostly want power delivered on their network links. So, PoE is essential for a lot of edge switches. New generations of devices want PoE+, with its higher power rating per device. And since a PoE switch might draw anywhere from five to 20 times as much power when serving PoE devices, IT has to do a careful evaluation of wiring closet power circuits and cooling measures to be sure they are up to snuff.
  • SDN: Perhaps the biggest technological transition for most networks is the introduction of software-defined networking. It may be pure, classic SDN, with central controllers driving an edge-to-edge network composed of generic data plane devices using OpenFlow as their lingua franca. It may be a more generic "new SDN" incarnation, supporting virtual networks and service-centered automatic provisioning and reconfiguration without going the OpenFlow route. As a result, the next round of campus switching should be SDN-ready, preferably understanding OpenFlow v1.3 or better. It should also support VXLAN and NVGRE for network virtualization without OpenFlow, and NetConf for a standards-based remote management API, which allows automation without an SDN controller.

The Nice-to-Have List

  • OpFlex: This protocol, introduced by Cisco (but pushed out into the open standards community) supports policy-drive automation of traditional-style network devices (those with their own dedicated control plane). Support for this protocol would keep your options open, but it's by no means necessary unless you are committed to seven more years of Cisco for strategic reasons.
  • Campus Fabric: The overarching goals of SDN are, in part, centered on making any network function like a data center fabric in terms of easy provisioning and reconfiguration. If the network can support that objective without forcing the move to controllers, OpenFlow and such, so much the better. 

The bottom line

The state of the art in campus switching is changing rapidly to meet the challenges created by SDN, mobility, wireless-only workers and the Internet of Things. Make sure your next campus switch purchases are positioned to meet those challenges head on.

About the author
John Burke is a principal research analyst with Nemertes Research, where he advises key enterprise and vendor clients, conducts and analyzes primary research, and writes thought-leadership pieces across a wide variety of topics. Burke's expertise is in virtual networks and software-defined networking (SDN) technologies, standards and implementations.

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This was last published in May 2015

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