We continue our look into the world of the Network Operating System (NOS) by examining the Linear Bus Topology. Both the peer-to-peer network operating system model and client/server network operating system model have seen deployment implementations using a linear bus topology.
Linear Bus Topology
The Linear Bus Topology is in many ways an extension of the Direct Link Topology but instead of a cable only connecting two machines as is the case with the Direct Link Topology the Linear Bus Topology extends the cable and nodes attach to a common cable which all network segment members share.
Where the Direct Link Topology requires each machine to have one NIC per node that it wishes to connect to the Linear Bus Topology only requires nodes to have one NIC. The fiscal savings that the Linear Bus Topology has over the Direct Link Topology begin at the very nature of both topologies and scale exponentially from there.
A Linear Bus Topology implementation requires a main run of cable with terminators at both unless the cable terminates directly with a nodes NIC. This however is not the recommended method as it can result in additional reflection collisions where Ethernet is concerned.
The “terminal” node(s) also receives generally poorer quality of service and accessibility to the common shared medium than its compatriots do.
The main cable run functions as the backbone of the network. Nodes and peripheral devices are very easy to connect to the Linear Bus Topology using “vampire” clamps. The terminators at the ends of the cable are to negate the effect of reflection collisions.
One big problem that the Linear Bus Topology has always faced is that in the event of a break in the main cable results in shut down of the entire segment. This can make the job of identifying and rectifying the true cause of the problem very difficult in deed.
The original design intentions for the Linear Bus Topology never included the large building stand-alone solution scenario. All nodes including file servers, workstations, printers and other peripherals connect directly to the main linear cable.
Both the Ethernet & LocalTalk (Apple's Proprietary Protocol) Network protocols can use a Linear Bus Topology.
Linear Bus Topology Advantages
- Ease of connecting a computer or other peripheral to a linear bus saw the Linear Bus Topology become very popular with small peer-to-peer networks
- A Bus Topology uses less cable than a Star Topology and is cheaper as a result
- The Linear Bus Topology also does not require the inclusion of central hubs, concentrators or switches and is cheaper than a Star Topology for this reason as well
Linear Bus Topology Disadvantages
- Terminators are required at both ends of the Linear Bus Topologies backbone cable
- A break in the main cable will result in the entire network shutting down which makes it very difficult to identify and rectify the true cause of the problem
- The Linear Bus Topology was never intended to be used as a stand-alone solution in a large building
Next time in “Network Operating System Star Topology”, we will discuss the Star Topology and its implementation indicators. Until then enjoy!
