InfiniBand Bus

[InfiniBand Description] [InfiniBand Interface ICs]
[InfiniBand Standards]

InfiniBand Description

InfiniBand [IB] uses (Point-to-Point) 2.5 GHz differential pairs (signalling rate)- one transmit and one receive - using LVDS and 8B/10B encoding.
Higher bandwidth connections are made by grouping 4 or 12 pairs together, for up to 3 GB/s full-duplex connections. InfiniBand is designed to be used over a Backplane, Copper wire or Fiber. The impedance for the PWB interface or cable interface is 100W. All inter-connections are Hot-Swappable on InfiniBand.

The specification defines a data rate of 250MBytes/sec for both electrical and optical signaling. That's a 2.5GHz signaling speed using 8B/10B [10 bits = 1 byte]

There are 3 interface widths; 1x, 4x, and 12x.
... 1X defines a interface with 2 differential pairs (as shown below). Same for Fiber, 1 Transmit, 1 Receive [Maximum bit rate is 2.5Gbps]
... 4X defines a interface with 8 differential pairs (4 per direction). Same for Fiber, 4 Transmit, 4 Receive [Maximum bit rate is 10Gbps]
... 12X defines a interface with 24 differential pairs (12 per direction). Same for Fiber, 12 Transmit, 12 Receive [Maximum bit rate is 30Gbps]

LVDS Bus Circuit implementation
1X Infiniband Interface Circuit

InfiniBand Physical Link
Link Signally Wires Signally Wires Data Rate Duplex Data Rate
1x 4 2.5Gbps 2.0Gbps 4.0Gbps
4x 16 10Gbps 8Gbps 16.0Gbps
12x 48 30Gbps 24Gbps 48.0Gbps

InfiniBand Protocol Description

Each IBA Packet [InfiniBand Architecture] begins with a Start-of-Frame [SOF], and ends with an End-of-Frame [EOF]. The Header field is made up of a Routing Header and a Transport Header. The Packet Payload follows the Header field. Two different Cyclic Redundancy Code [CRC] fields follow the Payload; ICRC [Invariant CRC] and VCRC [Variant CRC]. The Invariant CRC field covers the packets that do not change from source to destination, while the Variant CRC filed covers packets from link to link. Fill frames are used between packets.

InfiniBand Message Packet
InfiniBand Message Packet

InfiniBand Jitter Description

The IB specification has allocated a fixed Total Jitter [JT] of 0.25 UI for both the cable and connector regardless of cable length or connector size.
The maximum allowable Deterministic Jitter [JD] from the driver is 0.17 UI [without pre-emphasis]. The Total Jitter [JT] allowed from the driver is 0.35 UI.
The maximum allowable Deterministic Jitter [JD] at the receiver is 0.41 UI. The Total Jitter [JT] allowed at the receiver is 0.65 UI.

InfiniBand Mechanical Description

The InfiniBand specification defines the Physical, Electrical and Mechanical layers of an interface called the InfiniBand Architecture (IBA).
Cards (InfiniBand Modules), maybe 3U (Standard Module) or 6U (Tall Module) high, and are also a standard width (29mm) or 'Wide' modules (59mm).
They reside with in a metal case to provide EMI shielding. The thickness of the PWB isn't really defined, as long as it resides with in the EMI defined case.
The Chassis is also defined in the standard, as is cabling, Back plane and cable connectors.
The chassis requires a filler card for any empty slot.

InfiniBand Standards

InfiniBand Trade Association [The specification maybe down-loaded from this site]

InfiniBand Interface IC Manufacturers

Integrated Circuit Vendors:
Avago Technologies {8-port, 4x switch fabric IC}


LSI Corporation {CML Based SerDes with 10 or 20 Bit Interface, Octal 1.0-3.2 Gb/s Serial Repeater/Retimer}

Mellanox Technologies {4x InfiniBand Controller ICs - InfiniBand Switch ICs}

Zarlink Semiconductor {4 x 2.7Gbps Optical Transceiver}

InfiniBand Board Manufacturers

No OEM companies are currently listed.

PCIe Expansion card with Infinband Interface
PC based Infiniband Interface Card
PC motherboard

Distributor rolodex Electronic Components Electronic Equipment EDA CDROM Software Engineering Standards, BOB card Cabled Computer Bus Electronic Engineering Design Table Conversion DB9-to-DB25.
DistributorsComponents Equipment Software Standards Buses Design Reference

Modified 6/13/15
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