SCCT1023 Group A 30/8/09

Today, we continue our topic of data communication. We learn the topology and network. Network has 2 or more computers linked together to exchange data and share resource, they are LAN and WAN. Computers connected to a LAN are called workstations or nodes. LAN has 2 types, are peer-to-peer and client-server. The physical layout of a LAN is called its topology. Topologies resolve the problem of contention, which occurs when multiple users try to access the LAN at the same time. They have 5 types as ring, bus, star, tree and Mesh. We need to find out tree and mesh topology and paste it.

Mesh networking is a way to route data, voice and instructions between nodes. It allows for continuous connections and reconfiguration around broken or blocked paths by “hopping” from node to node until the destination is reached. A mesh network whose nodes are all connected to each other is a fully connected network. Mesh networks differ from other networks in that the component parts can all connect to each other via multiple hops, and they generally are not mobile. Mesh networks can be seen as one type of ad hoc network. Mobile ad hoc networks (MANET) and mesh networks are therefore closely related, but MANET also have to deal with the problems introduced by the mobility of the nodes.
Mesh networks are self-healing: the network can still operate even when a node breaks down or a connection goes bad. As a result, this network is very reliable. This concept is applicable to wireless networks, wired networks, and software interaction. The animation at the right illustrates how wireless mesh networks can self form and self heal. For more animations see History of Wireless Mesh Networking
Wireless mesh networks are the most topical application of mesh architectures. Wireless mesh was originally developed for military applications but have undergone significant evolution in the past decade. As the cost of radios plummeted, single radio products evolved to support more radios per mesh node with the additional radios providing specific functions- such as client access, backhaul service or scanning radios for high speed handover in mobility applications. The mesh node design also became more modular - one box could support multiple radio cards - each operating at a different frequency.

Tree Topology
Among all the Network Topologies we can derive that the Tree Topology is a combination of the bus and the Star Topology. The tree like structure allows you to have many servers on the network and you can branch out the network in many ways. This is particularly helpful for colleges, universities and schools so that each of the branches can identify the relevant systems in their own network and yet connect to the big network in some way.



A Tree Structure suits best when the network is widely spread and vastly divided into many branches. Like any other topologies, the Tree Topology has its advantages and disadvantages. A Tree Network may not suit small networks and it may be a waste of cable to use it for small networks. Tree Topology has some limitations and the configuration should suit those limitations.

Tree Network topology Benefits
A Tree Topology is supported by many network vendors ad even hardware vendors.
A point to point connection is possible with Tree Networks.
All the computers have access to the larger and their immediate networks.
Best topology for branched out networks.

Tree Topology Limitations
In a Network Topology the length of the network depends on the type of cable that is being used.
The Tree Topology network is entirely dependant on the trunk which is the main backbone of the network. If that has to fail then the entire network would fail.
Since the Tree Topology network is big it is difficult to configure and can get complicated after a certain point.
The Tree Topology follows a hierarchical pattern where each level is connected to the next higher level in a symmetrical pattern. Each level in the hierarchy follows a certain pattern in connecting the nodes. Like the top most level might have only one node or two nodes and the following level in the hierarchy might have few more nodes which work on the point to point connectivity and the third level also has asymmetrical node to node pattern and each of these levels are connected to the root level in the hierarchy. Think of a tree that branches out in various directions and all these branches need the roots and the tree trunk to survive. A Tree Structured network is very similar to this and that is why it is called the Tree Topology.
Tree Topology Features
There will be at least three levels of hierarchy in the Tree Network Topology and they all work based on the root node.
The Tree Topology has two kinds of topology integral in it, the star and the linear way of connecting to nodes.
The Tree Topology functions by taking into account the total number of nodes present in the network. It does not matter how many nodes are there on each level. Nodes can be added to any level of the hierarchy and there are no limitations a far as the total number of nodes do not exceed.
The higher levels in the hierarchy are expected to perform more functions than the lower levels in the network.



Tree Topology Conclusion
The signals that are being transmitted by the root node are received by all the nodes at the same time. This increases the efficiency of the over all functioning of the network. The Tree Network topology can be extended easily to function and there are no limitations to how big it can be extended. Additional root nodes can be added and they can be interconnected within one single network.