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Arista 10G switch: Fast and flexible

Linux-based core switch sets records with high density, blazing performance

By David Newman, Network World
March 26, 2012 12:07 AM ET

Network World - Packing 384 10G Ethernet ports into an 11-rack-unit form factor is only the beginning for Arista Networks' DCS-7508 data center core switch.

In this exclusive Clear Choice test, the 7508's performance set one high-water mark after another. It switched 5.7 billion frames per second, the highest throughput ever seen in a Network World test. It moved multicast traffic to more than 4,000 groups on all ports, another record for a modular switch. And it ran at wire speed in almost every case except when we deliberately congested the switch, and there it buffered up to 83MB per port.

Arista again looks to buck Cisco, others in data center

On top of its impressive performance stats, the 7508 also showed off multiple redundancy and load-balancing mechanisms and recovered quickly from failures. And it did all this running on Linux, with all the extensibility that comes with Unix-like operating systems.

For network managers wondering why they'd need this much port density: It might not happen this quarter or next, but 10G Ethernet is already well on its way to replacing gigabit as the pervasive data center transport.

The signs are all there: Intel is about to ship 10G-equipped server motherboards in quantity. A gaggle of storage vendors already send iSCSI traffic over converged 10G Ethernet backbones. And faster 40G and 100G Ethernet uplinks are starting to appear. Given the usual multi-year depreciation cycles for networking gear, high-density switches like Arista's 7508 are starting to make sense as data center workhorses.

A well-considered design

Beyond its high density, the 7508 offers some seriously nice hardware. Airflow is excellent, thanks to fans on each fabric card and a lattice inside the chassis. Power management allowed us to drive all 384 ports at full tilt using just two power supplies, instead of the standard four.

The design smarts extend to Arista's EOS software. Underneath a Cisco IOS-like command-line interface (CLI), EOS offers modularity and a complete Linux command set. Modularity, also seen in Cisco's NX-OS for Nexus switches, means the failure of any one process doesn't take down the entire system, as it would in monolithic designs like Cisco's mainline IOS. We verified this by intentionally killing EOS processes and watching them automatically respawn; there was no effect on other system functions.

But EOS's greatest strength is its extensibility. Because it's Linux under the hood, EOS is highly customizable. The vendor provides source code for its CLI and many other (though not all) system components and actively encourages customers to hack its code.

To demonstrate EOS extensibility, Arista recently gave a group of its developers and system engineers, including some non-programmers, 24 hours to get new projects running.. The team produced dozens of tools, ranging from useful (say you're on a Mac, and want Growl notifications when particular interfaces go up or down) to plain crazy (Pandora radio running on the switch, fed to external speakers via a $20 USB sound card). Essentially, any task that can run on Linux can probably run on EOS.

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