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Electronic Design

InfiniBand Chip Delivers HCA, TCA, And Switch Functions

InfiniBand is more than a paper tiger. Silicon and hardware are now emerging to implement this next-generation switch-fabric standard. One of the first devices to help deploy the InfiniBand architecture is Mellanox's MT21108. This chip functions as a fully integrated eight-port switch, a host channel adapter (HCA), and a target channel adapter (TCA).

The MT21108 may be used to build an InfiniBand switch fabric by furnishing the host InfiniBand link (the HCA), the intermediate InfiniBand switch elements, or the target device InfiniBand link (the TCA). Each of its eight ports can operate at a peak 2.5 Gbits/s with 8/10-bit encoding. These ports can be configured as eight 1x InfiniBand links or any combination of 1x and 4x links.

The MT21108 is an internal 32/64-bit PCI interface that clocks up to 66 MHz with a peak bandwidth of 528 Mbytes/s. A host CPU using the virtual interface (VI) connects to the switch fabric via the MT21108, which is used at the target device to implement an InfiniBand TCA.

At the core of the chip is a crossbar switch and scheduling engine that connects the links and interfaces. It supports link-to-link connections and can connect to its PCI interface. The chip has an onboard processor that's coupled with a forwarding database (FDB) to handle link routing. Mapping for up to 16k InfiniBand local ID (LID) entries is provided by the FDB.

Able to handle full wire-speed switching, the MT21108 supports InfiniBand virtual lanes (virtual subsets of a connection) and credit-based switch flow. Plus, it implements "cut-through" switching, which makes the connection before the incoming packet is complete. Another feature of this chip is that it sends and receives management datagrams (MADs). In addition, it incorporates a subnet management agent (SMA), which takes in MAD configuration packets and can send MAD event notification to the subnet manager.

Available in a 516-pin PBGA package, the MT21108 comes with an I2C EEPROM interface, an 8-bit CPU interface, and a JTAG port. It's priced at $196 per piece in 10,000-unit packages. Also offered is a product development kit, which contains a PCI board and software, priced at $5000. The board was designed for use as an InfiniBand HCA, TCA, or switch.

Mellanox Technologies Inc., 2620 Augustine Dr. #245, Santa Clara, CA 95054; (408) 566-0220; Internet:

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