InfiniBand Standards

InfiniBand is a communication standard used for high-speed data transfer. It is mainly used in systems that require high bandwidth and low latency, such as supercomputers and data centers. The following is a brief description of InfiniBand standards and cables.

InfiniBand Standards

There are several versions of the InfiniBand standard, depending on the transmission speed and cable type. Each standard is determined by the number of link lanes (pathways through which data is sent) and communication speed.

Standard	Number of links (x)	Speed (Gbps)	Total Bandwidth (Gbps)
SDR (Single Data Rate)	1	2.5	2.5
	4	2.5	10
	8	2.5	20
DDR (Double Data Rate)	1	5	5
	4	5	20
	8	5	40
QDR (Quad Data Rate)	1	10	10
	4	10	40
	8	10	80
FDR (Fourteen Data Rate)	1	14.0625	14.0625
	4	14.0625	56.25
	8	14.0625	112.5
EDR (Enhanced Data Rate)	1	25	25
	4	25	100
	8	25	200
HDR (High Data Rate)	1	50	50
	4	50	200
	8	50	400
NDR (Next Data Rate)	1	100	100
	4	100	400
	8	100	800

The communication bandwidth of InfiniBand increases with the number of links and the data rate of the links. The number of links typically includes x1, x4, x8, x12, etc.

Types of InfiniBand Cables

There are two main types of InfiniBand cable: copper and fiber. Each can be used for different purposes and over different distances.

Copper Cables

DAC (Direct Attach Copper): Passive cable for short connections, typically 1 to 7 meters. Its low cost makes it suitable for short server-to-server connections.

Fiber optic cable

Fiber optic cables are suitable for long-distance connections, typically tens of meters to several kilometers. They are used in data centers and other locations where high-speed, long-distance connections are required.

Connector Types

QSFP (Quad Small Form-factor Pluggable) is the primary connector type used for InfiniBand cables.

QSFP: An interface that enables high-speed connections, has x4 links, and is used for connections that require high bandwidth.

How to choose a cable

• Distance: Choose copper for short distances (1-7 meters) and fiber for longer distances.
• Speed: Depending on the InfiniBand speed standard (FDR, EDR, HDR, NDR), you will need the appropriate cable.
• Bandwidth: Depending on the number of links (x1, x4, etc.), different cables are used.

InfiniBand standards continue to evolve and are widely used in data centers and high performance computing (HPC) where high-speed communications are required. Understanding the characteristics of each standard and cable is important for system design.

Translated with AI