Switch Structure Past - Now and Bare Metal
Traditional networking gears in the pas had a complete proprietary architecture. vendors used to design their own ASIC (Chipsets) and use them in the networking equipment.
In last couple of years, chipset vendors such as Broadcom, Marvel, Mellanox, Vitesse (Acquired by Microsemi) and Cavium started producing Ethernet switching ASICs with lots of features and higher switching throughput. these chipsets are also known as Merchant Silicons.
The use of Merchant Silicon in enterprise networking products started growing in 2009, where vendors realized that the merchant silicon provide a higher throughput and costs less comparing to building a proprietary ASIC. So vendors started outsourcing the complete switch production to ODM companies, however and they kept the switch software in their hands.
Bare Metal switches are the same hardware which has been produced by ODM for other vendors, but they don't have any operating system.