Used for enterprise level network topologies because

used for enterprise-level network topologies because of its high susceptibility to faults and system downtime. If a link
between routers becomes faulty, the whole network may get disrupted, as there are no alternate data transmission
routes. Therefore, this type is only used in small network setups.
Distributed Backbone
The distributed backbone network comprises a hierarchical formation of devices that are adaptable to multiple
connectivity. For example, if multiple devices are connected to switches, these form the intermediary devices
connecting to the backbone router and gateway devices.

The distributed backbone network, unlike the serial backbone network, is well suited for enterprise-wide connectivity.
Expanding and troubleshooting the network is simple, as layers of the network are easily added and managed.
Collapsed Backbone
The collapsed backbone network makes use of a single, high specification router that serves as the central
connection supporting the rest of the network. As the backbone, it's characterized by high computational power to
adequately handle the traffic from various networks. With this setup, the entire network is dependent on this single
router, making the network extremely vulnerable. If the router goes down for any reason, so does the entire network.
This type of backbone topology is mainly applicable in situations where two different types of sub networks need to
be connected and managed effectively.
Parallel Backbone
Parallel backbone networks employ a system of replicated connections to the backbone infrastructure. In this
system, nodes and switches are implemented with duplicate concurrent connections to the high-level backbone
routers. Not all nodes need to have the parallel connection, but strategic points of the network could be designed as
such.
Because the connections function concurrently, network availability at all times is ensured. This setup also ensures
high network speeds, robustness, and high fault tolerance. With this replicated setup, implementation costs get
expensive with the increased cabling. The parallel backbone is a variation of the collapsed backbone infrastructure
used to connect and managed different types of sub networks effectively.
Lesson Summary
Backbone networks are networks designed with high capacity connectivity infrastructure that form the main link, or
backbone, connecting the different parts of the network. The network consists of various LANs, WANs, and sub
networks. The backbone normally comprises of high specification routers and gateways.
Different types of backbone networks include:
 The serial backbone : uses two or more connected devices linked to each other by hubs. It's simple and
easy to implement but is only used in small network setups because of its high susceptibility to faults and
system downtime.
 The distributed backbone : spans a larger network with multiple sub networks connected.