Different network topologies have different advantages and disadvantages. A bus network topology is nice because it is simple and cheap, however it has its limitations. On a bus topology you are limited to the number of hosts you can place on a single bus. A ring topology can be beneficial because it provides redundancy, however if more than one node along the bus goes down, this will break the ring and can seriously impact the functionality. A star topology can easily be deployed, but once again, if the node or hub in the center of that star goes down, then each host off that connection will be isolated. A mesh topology would be the most ideal topology for larger networks, however it is more expensive and can be more difficult to deploy since there will be more connections needed for the infrastructure. Another advantage of a mesh topology is the redundancy the infrastructure provides. As you can see, there are advantages and disadvantages of each network topology and each type of topology has its place of where it should be deployed.
There are many different types of networking standards that were developed to ensure there is a certain degree of development standardization, stability and availability among networks. Cable standards are there to ensure that the type of physical media being used is rated for the distance and speeds it can handle before degradation begins. Wireless standards (IEEE 802.11 and 802.15 standards) were developed to ensure there is a certain degree of access and ensuring communication between systems over a wireless connection. The IEEE 802.3 LAN/MAN/CMSA/CD standard was developed to ensure there are an access method, physical layer specifications, and network management specifications. Some standards are to ensure the smooth evolution and development of the internet, such as the function of the Internet Engineering Task Force. No matter what the standard is, the standardization process provides guidelines for all to follow to ensure devices will work with each other.
Networking protocols are how different devices are able to communicate with each other. The most widely used internet protocol used today for network equipment to talk with each other is TCP/IP. Currently when using TCP/IP the most widely used version is internet protocol version 4, which is 32 bit. IPv4 has met the needs of the internet until recent years. IPv4 is restricted by the number of unique IP addresses are available for the whole Internet to use, that number being 4,294,967,296. IPv6 is the next version that will be coming out, which expands on IPv4 and provides many more IP addresses to be used and seems to have a limitless number of IP addresses due to it being 128 bit. Even though a device is physically connected to a network and has met standards, without network protocols the device will not be able to communicate with other devices on that network.
When devices on a network use protocols to communicate with each other, access methods are used to determine which device is able to transmit or receive at a time without interfering with other devices. Carrier sense multiple access (CSMA) performs this function by a device determining if it sees a carrier on the media, if the host sees a carrier it knows not to transmit, but if it does not then the host can transmit it’s data. There are two types of CSMA one being collision avoidance and the other being collision detection. With collision avoidance, devices try to determine when a collision might occur and then they don’t transmit during that time. With collision detection, two devices sense there is nothing being transmitted and then they transmit at the same time and a collision occurs. Both devices then wait for a random amount of time before they retransmit. Another access method is token passing, token passing method works by simply a token being passed around and whoever holds the token is allowed to transmit. No matter what access method is used, this is how devices are able to share media and determine that every device is not trying to transmit at the same time.
Networks are connected to other networks by various different methods. Networks can be interconnected by different ways of transmission, some of those methods are satellite, microwave, high frequency, integrated digital switched network, Ethernet, thicknet, thinnet, token ring, asynchronous transfer mode, etc. The means of how these networks are connected may impact what types of network interfaces we use to communicate with the networks. For example: if thicknet (Coaxial cable) is used for the network, then the host would definitely need a BNC connector to interface with the network. If ATM is used, more than likely a fiber optic NIC would need to be utilized to talk on the ATM network. Networks are connected to each other in various different way, depending on what method is used to interconnect networks may impact what network interfaces are needed to connect to different media types.
In conclusion, there are many different ways a network can be designed, connected, and accessed based upon different standards. Different topologies can be used to provide a layout for different networks. Each individual network adheres to different networking standards. Depending on the type of network, different methods can be used for accessing the network and in turn different types of media may be used to connect these networks.
References:
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http://www.linktionary.com/a/access_method.html
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