Black Box Explains... Bridges
If you work with legacy networks, you have doubtlessly encountered bridges. Bridges perform the same function as today’s switches in that they connect multiple network segments to create one homogenous... more/see it nownetwork, while keeping each segment isolated from the others.
Bridges operate on MAC-layer addresses and are protocol independent, so they transfer data between workstations without understanding the protocol. Since they don’t have to understand the protocol, they require little or no configuration.
Once you connect the bridge to the network, it automatically learns the addresses of all connected nodes and then creates an internal address table of this information.
When the bridge sees a packet, it checks the packet’s destination address against its internal list. If the address indicates the packet needs to be forwarded, the bridge passes the packet to the appropriate segment. If a bridge doesn’t know where a packet belongs—for example, when a station is first powered on—it passes on the packet.
Bridges can also distinguish between local data and remote data, so data traveling from one workstation to another in the same network doesn’t have to cross the bridge.
Although they are no longer in general use, Black Box stocks bridges for use as replacement parts in legacy networks. Replacing bridges with bridges rather than switches is often preferable because bridges are generally available with the BNC and AUI interfaces often found in older networks. Also, some bridges are able to link to other protocols such as RS-530 and X.21, enabling you to use these media to establish Ethernet network connections.
Black Box Explains...Using repeaters to extend your network.
A repeater is a signal regenerator. It amplifies and regenerates received data and relays data from one length of cable to another—this can be between two segments of the same... more/see it nowcable type (such as UTP to UTP) or between two lengths of entirely different cable types (such as UTP to ThinNet). Because repeaters operate at the Data Link layer of the OSI model, having too many repeaters on a network introduces delays and causes problems with signal timing. Ethernet allows a maximum of two IRLs (InterRepeater Links) between any two devices and up to four per network. A hub also counts as a repeater. (If simple media conversion is your goal, use media converters instead. For details, contact Tech Suport.)
Repeaters boost distance by amplifying the signal.
A repeater actually regenerates and amplifies the signal to gain distance. The repeater not only changes the media type, it also gives the signal a boost to send it over a longer distance.
Repeaters boost distance through a change in media.
In addition to amplifying the signal, a repeater can also add distance to your network by enabling you to change to a media type such as fiber that supports longer distances. collapse
Black Box Explains...Media converters.
Media converters interconnect different cable types such as twisted pair, fiber, and coax within an existing network. They are often used to connect newer Ethernet equipment to legacy cabling.... more/see it nowThey can also be used in pairs to insert a fiber segment into copper networks to increase cabling distances and enhance immunity to electromagnetic interference (EMI).
Traditional media converters are purely Layer 1 devices that only convert electrical signals and physical media. They don’t do anything to the data coming through the link so they’re totally transparent to data. These converters have two ports—one port for each media type. Layer 1 media converters only operate at one speed and cannot, for instance, support both 10-Mbps and 100-Mbps Ethernet.
Some media converters are more advanced Layer 2 Ethernet devices that, like traditional media converters, provide Layer 1 electrical and physical conversion. But, unlike traditional media converters, they also provide Layer 2 services—in other words, they’re really switches. This kind of media converter often has more than two ports, enabling you to, for instance, extend two or more copper links across a single fiber link. They also often feature autosensing ports on the copper side, making them useful for linking segments operating at different speeds.
Media converters are available in standalone models that convert between two different media types and in chassis-based models that connect many different media types in a single housing.
Rent an apartment
Standalone converters convert between two media. But, like a small apartment, they can be outgrown. Consider your current and future applications before selecting a media converter. Standalone converters are available in many configurations, including 10BASE-T to multimode or single-mode fiber, 10BASE-T to Thin coax (ThinNet), 10BASE-T to thick coax (standard Ethernet), CDDI to FDDI, and Thin coax to fiber. 100BASE-T and 100BASE-FX models that connect UTP to single- or multimode fiber are also available. With the development of Gigabit Ethernet (1000 Mbps), media converters have been created to make the transition to high-speed networks easier.
...or buy a house.
Chassis-based or modular media converters are normally rackmountable and have slots that house media converter modules. Like a well-planned house, the chassis gives you room to grow. These are used when many Ethernet segments of different media types need to be connected in a central location. Modules are available for the same conversions performed by the standalone converters, and 10BASE-T, 100BASE-TX, 100BASE-FX, and Gigabit modules may also be mixed. collapse