Network Design

What Is a Backbone?

A backbone is a network segment or cable which is used to provide for the interconnection of a number of smaller workgroups or self-contained networks. The outlying networks, workgroups, or hubs communicate with one another through the backbone network.

The use of a dedicated network acting as a backbone, tying all the separate networks together, is of benefit for several reasons.

Using a single network to handle the extremely important connections between networks allows Network Designers to use highly reliable technologies and cables. These designs are frequently expensive, and using them, initially, in the backbone network provides the benefits of these technologies or media without requiring the expense of providing that level of service to all points of the network.

A backbone network can be migrated out to the workgroups as the facility-wide network grows. As more users are added, it is often much easier to attach a concentrator or hub to a small backbone network than to continue expanding workgroups that may be already quite congested. In addition, the backbone can provide a point from which a higher-speed technology can be ‘painted out’ to the rest of the network as needs dictate and as money becomes available.

Since the amount of communications passing between several workgroups or hubs in an entire facility or campus is often quite large, backbone networks often use higher-speed networking technologies than those of the workgroup networks. A very common workgroup and backbone scenario involves several Ethernet workgroups in a building or campus connected to an FDDI backbone. This offers the communications passing between the separate Ethernet networks, operating at under 10 Mbps, to access a highly reliable and available 100 Mbps network for communications between workgroups.

Methods of Configuring Backbones

Backbone networks can be set up in a number of different ways. This Networking Guide presents three of the most common means of configuring backbone networks. Almost any backbone network implementation may be designed from the following basic backbone types:

Distributed Backbone

Collapsed Backbone

Device Collapsed Backbone

The Workgroup in the Larger Network

5-17

Page 57
Image 57
Cabletron Systems bridges, switches manual What Is a Backbone?, Methods of Configuring Backbones