Section Objectives
After you complete this section you will:
Understand network topologies.
Understand ways to increase bandwidth.
Identify network problems.
Network Topologies
The topography of a network is the physical arrangement of elements in a network.
Bus Topology
A type of network where all of the nodes (connected devices) are connected via the same bus. In the bus topology, all of the nodes are connected via the same cable as each other. Also known as linear topology.
Fully Connected Topology
In a fully connected topology, all of the nodes have a direct connection to each other.
Hybrid Topology
Two or more types of networks connected together.
Mesh Topology
Network type where there are two nodes with two or more paths between them.
Ring Topology
A type of network where each node has two connections to it.
Star Topology
A network topology in which all of the nodes communicate with a central node which passes communication throughout the network. If one node on the network loses its connection to the central node, that node cannot communicate with the network.
Most Common Topology
The most common type of network topology is the hybrid topology, a combination of two or more types of topologies.
Increasing Bandwidth
Upgrading from 10 Mbps to 100 Mbps
One of the most cost effective ways to upgrade network bandwidth within a local area network is to upgrade the nodes and networking devices to 100 Mbps.
Typically, a company builds a 10BaseT Ethernet network inside a building with CAT5 cabling. Each networking card inside each workstation operates at 10 Mbps or 10/100 (10 Mbps or 100 Mbps).
In a medium to large network, you will have several switches or hubs on the network to direct traffic. These switches or hubs run at a given speed, usually either 10 Mbps or 10/100 Mbps. Upgrading these to 10/100 switches or hubs and upgrading the network cards to 10/100 will allow those clients to run at 100 Mbps.
Network Problems/Degradation
A network collision is when two streams of data from two devices on an Ethernet network are transmitted at the same time and collide. The network detects the collision and discards both packets of data and request new ones from the source. A collision is a natural occurrence on Ethernet networks. Too many collisions and your network bandwidth degrades as requests for new packets and more collisions take their toll.
With managed switches, you can view how many collisions are occurring on the switch. With millions of packets transmitted an hour on busy networks, you can easily notice a trend if you collision rate starts climbing. Too many collisions can be a sign of a bad device or card connected to the network.
Network Chatter
Network chatter is a non-technical term for the traffic on your network which is discovery or traffic which may not seem to serve much of a purpose. Certain servers or devices may seem to “chatter” constantly, sending out packets but for no real purpose.
For example, I worked at a company which had about 30 file servers on the network. Out of the 30, all but one were Windows NT or 2000, the remaining one was a Netware 4.10 server. The Netware server caused so much “chatter” on the network that when we would remove it, our network traffic would drop 50%. Netware servers sometimes have the tendency to send out unneeded packets to clients other than their own as a method of discovery or communication.
After studying this section you should:
Understand network topologies.
Understand ways to increase bandwidth.
Identify network problems.
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