How is SFP Cable Data Transmission Defined by Bandwidth

The SFP+ cable data transmission or distance is defined by the modal bandwidth of the module. For example, the Cisco 10GBASE-SR SFP module (SFP-10G-SR) is supported by a bandwidth of 2000MHz*km MMF (OM3), up to 300m link lengths are possible. Once the bandwidth is increased to 4700MHz*km MMF (OM4), which makes 400m link lengths possible. As the bandwidth increases, the distance increases.

Generally speaking, the link lengths change based on the bandwidth supported, but also the core size is also a factor. Typically, core sizes will range between 62.5 microns to 50 microns. When choosing SFP+ modules for many different applications, both of these criteria should be thought about. There are a few examples of how different devices support this technology.

Cisco SFP-10G-LRM

The SFP-10G-LRM is created to support link lengths of 220 meters on standard fiber distributed data interface grade multi-mode fiber (MMF). The bandwidth on this module is mid-range that allows a mid-range data transmission distance to be achieved. Generally speaking, the higher the bandwidth the longer distance that can be traveled. In order to over OM1 and OM2 fibers and obtain maximum distances, the transmitter must be coupled with a conditioning patch cord. But no mode conditioning patch cord is required for applications over OM3 or OM4.

Fabric Extender Transceiver (FET-10G)

This FET-10G fabric extender transceiver uses a modal bandwidth of 500 MHz*km (OM2), which makes 100m link lengths possible. A larger bandwidth can send perpetuate the speed of the data faster and farther, but these links can only be achieved on OM3 (2000 MHz*km) or OM4 (4700MHz*km) that has been optimized by laser. The product is only available with certain companies and is compatible with certain types of switches (i.e. Cisco Nexus 2000 Series).

SFP-10G-BXD-I and SFP-10G-BXU-I

A SFP-10G-BXD-I device is always connected to a SFP-10G-BXU-I device with a single strand of standard SMF with an operating transmission range up to 10 km. These type of device are recommended if the user needs to monitor SFP parameters in a real-time environment. Instances of applications include temperature, optical output and input power, laser bias current, as well as, transceiver supply voltage. SFP-10G-BXD-I and SFP-10G-BXU-I are versatile type of device that's utilized in various situations.

SFP+ Direct Attached Twinax Copper Cables

Cisco SFP+ direct attach Twinax copper cables are capable of achieving short distances in a cost effective manner. These SFP+ DACs can transmit lengths from 1 to 5 meters in increments of 0.5 meters. And SFP+ active Twinax cables support lengths of up to 7 to 10 meters. As it is one of the most cost efficient solutions, more designers are selecting to this solution.

Why You Should Purchase SFP+ Modules

Besides their capability to transmit signals for long distances, a number of the devices possess some of the smallest form factors in the industry. They are hot swappable and have the capability to plug into an Ethernet SFP+ port. Data migration or technology migration is easy since it is a hot swappable device. Additionally, there are built-in diagnostic capabilities available with some SFP+ modules.

If distance is the concern, the modules are more than capable of achieving the distances necessary for the application. Each application must be evaluated on an individual basis to determine the core size and bandwidth necessary to achieve the desired link length. Once this is determined, a selection can be made based off the reputation of the manufacturer and the desired application.