Bus network
Network whose topology is characterized by having a single communications channel (called bus, trunk or backbone) to which the different devices are connected. In this way all devices share the same channel to communicate with each other.
The bus topology has all its nodes connected directly to a link and has no other connection to each other. Physically each host is connected to a common cable, so they can communicate directly. The cable break causes the hosts to be disconnected.
The ends of the cable are terminated with a coupling resistor called terminator, which in addition to indicating that there are no more computers at the end, allow the bus to be closed by means of an impedance coupling.
It is the third of the main topologies. The stations are connected by a single cable segment. Unlike a ring network, the bus is passive, there is no signal generation at each node.
Advantage
Ease of deployment and growth.
Economic.
Simplicity in architecture.
Disadvantages
Limited channel lengths.
A problem in the channel usually degrades the entire network.
Performance decreases as the network grows.
The channel needs to be properly closed (closed roads).
High transmission losses due to collisions between messages
STAR NETWORK
A star network is a network in which the stations are directly connected to a central point and all the communications that must necessarily be made through it.
Given its transmission, an active star network has an active central node that normally has the means to prevent echo related problems.
It is used mostly for local networks. Most local area networks that have a router, a switch, or a hub follow this topology. The central node in these would be the router, the switch or the hub, through which all packets pass.
Advantage
It has two means to prevent problems.
It allows all nodes to communicate with each other conveniently.
Disadvantages
If the central node fails, the entire network is disconnected.
It is expensive, since it requires more cable than the Bus and Ring topology.
The cable travels separately from the hub to each computer
Ring network
Network topology in which each station is connected to the next and the last is connected to the first. Each station has a receiver and a transmitter that acts as a repeater, passing the signal to the next station.
In this type of network the communication is given by the passage of a token or witness, which can be conceptualized as a mailman who passes collecting and delivering information packages, thus avoiding possible loss of information due to collisions.
It is worth mentioning that if any node in the network stops working, communication throughout the ring is lost.
In a double ring, two rings allow data to be sent in both directions. This configuration creates redundancy (fault tolerance), which means that if one of the rings fails, the data can be transmitted by the other.
Advantage
· Simplicity of architecture. Ease of implesion and growth.
Disadvantages [edit]
· Limited channel lengths.
· The channel will usually degrade as the network grows.
Mesh network
The mesh topology is a network topology in which each node is connected to all nodes. In this way it is possible to take messages from one node to another by different paths. If the mesh network is completely connected, there can be absolutely no interruption in communications. Each server has its own connections with all other servers.
The establishment of a mesh network is a way to route data, voice and instructions between nodes. Mesh networks differ from other networks in that the elements of the network (node) are all connected to all, by separate cables. This configuration offers redundant paths throughout the network so that, if one cable fails, another will take care of the traffic.
This topology, unlike others (such as tree topology and star topology), does not require a central server or node, which reduces maintenance (an error in a node, whether important or not, does not imply the fall of the entire network).
Mesh networks are auto routable. The network can work, even when a node disappears or the connection fails, since the rest of the nodes avoid passing through that point. Consequently, the mesh network is transformed into a very reliable network.
It is an option applicable to wireless networks (Wireless), wired networks (Wired) and node software interaction.
A network with mesh topology offers superior redundancy and reliability. Although the ease of troubleshooting and increasing reliability are very interesting advantages, these networks are expensive to install, since they use a lot of wiring. Therefore, they become more important in the use of wireless networks (due to the lack of wiring) despite the inconveniences of Wireless.
In many cases, the mesh topology is used together with other topologies to form a hybrid topology. It is connected to a server that sends other computers
A mesh network effectively extends a network, sharing access to a larger infrastructure.
Tree network
Network topology in which the nodes are placed in the form of a tree. From a topological view, the tree connection is similar to a series of interconnected star networks except that it does not have a central node. Instead, it has a trunk link node, usually occupied by a hub or switch, from which the other nodes branch. It is a variation of the bus network, the failure of a node does not imply interruption in communications. The same communications channel is shared.
The tree topology can be seen as a combination of several star topologies. Both the tree and the star are similar to the bus when the interconnection node works in broadcast mode, since the information is propagated to all stations, only in this topology the branches extend from a root point ( star), as many branches as possible, depending on the characteristics of the tree.
No comments:
Post a Comment