Media converters bridge fibre gap

The idea that upgrading a network to fibre requires tearing out the existing copper infrastructure is a misconception. And it keeps many companies from switching to fibre.

Media converters, which change signals on a copper cable to signals that run on fibre, let a company introduce fibre in the network without making other changes.

Because of this capability, network executives who need to upgrade their systems from copper to fibre but don’t have the budget, manpower or time, can turn to media converters.

Media converters, a proven solution for LANs, are playing a role in facilitating the optical last-mile connection to the metropolitan-area network (MAN) and beyond.

As service providers race to deliver fibre-based services to businesses, the major challenge is that 80 per cent of the wiring of today’s LANs continue to be copper, while the physical layer infrastructure of MAN and WAN is always fibre. The migration of Ethernet and other protocols from the LAN to the MAN and WAN requires that copper and fibre coexist. Media converters can help ease that transition.

Media converters work on the physical layer of the network. They receive data signals from one media and convert them to another while remaining invisible to data traffic and other net devices. They make one cable “look” like another cable without changing the nature of the network.

In its simplest form, a media converter is a small device with two media-dependent interfaces and a power supply. It can be installed almost anywhere in a network. The style of connector depends on the selection of media to be converted by the unit. In a Fast Ethernet environment, a 100Base-TX to 100Base-FX Media Converter connects a 100Base-TX twisted-pair device to a 100Base-FX compliant single or multimode fibre port that has a fibre-optic connector. In a Gigabit Ethernet, a media converter commonly is deployed to convert multimode to single-mode fibre.

Media converters are as simple to install as patch cables and connectors. Media converters function as physical layer devices; they do not interfere with upper-level protocol information. This lets them support quality of service and Layer 3 switching.

For densely populated installs, up to 16 or more devices can be rack-mounted in chassis-style devices. These chassis-style products can be managed with SNMP so that the media converter becomes just another element in the network diagram – not a black hole.

Media converters were designed to be implemented in Ethernet networks and some ATM applications.

Because media converters are transparent, they do not change speed or duplex mode. Rather, they let the end devices determine the highest common denominator. The speed must be homogenous. Data cannot successfully pass when there is a mismatch of speed and/or duplex mode.

A media converter isn’t a bridge or a switch. It doesn’t look at addresses or other data. A media converter isn’t a repeater and doesn’t recognize or react to collisions. It passes bits through one by one.

How do you know if you should use media converters?