Media converter

A media converter is a device that converts a signal between copper cable (twisted pair) and optical fiber. It is used where the network needs to be extended beyond the distance allowed by twisted pair, or to connect a remote object to a backbone line.

What is a media converter

A media converter is a device that converts the physical data transmission medium. On one port it receives a signal over twisted pair (for example, RJ-45 10/100/1000 Mbps), converts it to optical and transmits it through an SFP port over fiber, or vice versa. A media converter operates at the physical layer of the OSI model and is transparent to protocols: it does not analyze packets, but only changes the signal form. Thanks to this, pairs of converters allow connecting two copper devices at distances of up to tens of kilometers through an optical backbone.

Why a media converter is needed

Twisted pair of category 5e supports transmission up to 100 meters at 1 Gbps. If you need to connect buildings, floors or a remote object further than this distance, optical cable and media converters are used: one is placed at the signal source, the second at the recipient. Media converters are used when connecting surveillance cameras, remote offices, server cabinets and equipment that does not have an optical port. This is cheaper and simpler than replacing a switch or installing an optical port, and allows gradually moving the network to optics. Converters also serve to connect equipment with different speeds and interface types.

Types of media converters

By port type there are 10/100 Mbps and gigabit (1000 Mbps) converters, as well as models with PoE support for powering cameras and access points over twisted pair. By design there are desktop devices and chassis — multi-module cases for installation in a rack, combining dozens of converters. The optical port is usually made as an SFP or SFP+ slot into which a transceiver module of the required type and range is inserted. Single-mode and multimode converters are distinguished, differing in the fiber type and the maximum transmission distance. Some models support “master/slave” modes and automatic speed negotiation.

How to choose and install a media converter

When choosing, take into account the network speed, fiber type (single-mode for long distances, multimode for short), transmission range and equipment power. For cameras and access points, choose models with PoE so as not to run separate power. The converter is usually configured without software: it is enough to connect the cables and insert a suitable SFP module, and the indicators will show the state of the link. When installing a pair of converters, it is important that the modules and fiber match each other in type and wavelength. For centralized placement of converters in a server room, a chassis with common power and redundancy is convenient.

Monitoring and status indication

The channel state is shown by indicators on the case: power, copper link, optical link and transmission activity. If there is no connection, check the match of the fiber and the SFP module, the integrity of patch cords and the correct orientation of the cables. Pairs of converters are configured automatically, and when using a chassis, the state of modules is controlled centrally by common power and indication. For complex networks, managed models supporting SNMP and remote polling of port status are chosen.