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Broadcom Axes Ethernet-Switch Foes

December 26, 2017

Author: Bob Wheeler

Competitors’ hopes that Broadcom would ease off the gas pedal just evaporated. The company is sampling the industry’s first 12.8Tbps Ethernet switch chip, once again doubling bandwidth relative to its prior-generation switch for hyperscale data centers. Using 56Gbps PAM4 serdes, Tomahawk 3 also supports the new 50Gbps, 200Gbps, and 400Gbps Ethernet standards. Meanwhile, competing chips that were announced earlier have yet to reach customers.

Externally, Tomahawk 3 offers unsurprising speeds and feeds. The top-end BCM56980 implements up to 32x400GbE, 64x200GbE, and 128x100GbE ports. It instantiates 256 serdes that handle 56Gbps PAM4 for the new standards as well as 28Gbps NRZ for backward compatibility with 25G Ethernet and four-lane 100G Ethernet specifications. Broadcom claims it reduced power per 100GbE port by about 40% while using the same 16nm technology as Tomahawk 2.

The company implemented a new unified buffer, addressing a shortcoming of Tomahawk 2 that competitors had laid bare. To serve the growing number of virtual machines and containers in cloud data centers, it roughly doubled Tomahawk 3’s table sizes. Instrumentation enhancements include in-band network telemetry (INT) and other new features exposed through APIs and the BroadView agent.

Startup Innovium was first to announce a 12.8Tbps switch chip, but it failed to deliver samples in 3Q17 as promised. Mellanox preannounced a 6.4Tbps chip that also handles 50GbE, 200GbE, and 400GbE ports, but samples are now due in mid-2018. By contrast, Broadcom doesn’t announce chips until they’re at least sampling to lead customers. Now, competitors must fight back with unique features instead of comparisons to Tomahawk 2, which is already in production.

Subscribers can view the full article in the Microprocessor Report.

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