Ethernet Networking in a Nutshell:
First, we have to understand how Ethernet works. For a nicely summarized history as well as an explanation of the type of media it can run on, you can click here.
Assuming everything is on the same network....... When a computer wants to talk to another computer on your network it 'listens' to see if there is any other traffic on the wire it is attached to. If it detects that it is all clear, it will send its traffic. Sometimes (and the likelihood increases the more computers you have on your network and the more heavily it is used) two hosts will send their data at the same time. When this happens, a collision occurs. When a collision is detected, a timer starts on each of the hosts which must expire before it will attempt to send traffic again. Meanwhile, while this is happening, the user staring at the monitor is busy complaining about how slow the network is.
Now, when host 'A' tries to access a resource from host 'B' for the first time it will send a broadcast to every host on the network asking for host 'B' to tell it where it is at. All the rest of the hosts on the network will receive this broadcast, look at the request, and decide "He's not talking to me" and purge the request from its NIC memory buffer. Host 'B', however, will say "Oh, that's me!" and respond with it's MAC address. Host 'A' will then write that address into its address resolution protocol (ARP) cache, and from that point on when 'A' wants to talk to 'B', it will attempt to talk directly to 'B' by using its MAC address. If all your hosts are attached to hubs, you begin to run into a problem. Why? Because a hub broadcasts all information that it receives in a port (that's a physical port on the device, not the...
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...nnected through four repeaters, or concentrators, and only three of the five segments may contain user connections.
The Ethernet protocol requires that a signal sent out over the LAN reach every part of the network within a specified length of time. The 5-4-3 rule ensures this. Each repeater that a signal goes through adds a small amount of time to the process, so the rule is designed to minimize transmission times of the signals.
The 5-4-3 rule -- which was created when Ethernet, 10Base5, and 10Base2 were the only types of Ethernet network available -- only applies to shared-access Ethernet backbones. A switched Ethernet network should be exempt from the 5-4-3 rule because each switch has a buffer to temporarily store data and all nodes can access a switched Ethernet LAN simultaneously.
Hopefully this information will assist in starting your networks correctly.
Switches use ports and sends information to a physical device address via these ports. They only send information to the particular computer that has the specific address and not to all of the computers.
“The Spanning Tree Protocol (STP) is an older network protocol that ensures a loop-free topology for any bridged Ethernet local area network. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them.”
Ethernet is often built into hardware devices such as network interface controllers, to allow the sending and receiving of data packets to that piece of hardware. Ethernet can be used to create a wired local area network, which can subsequently communicate with other LAN’s, ad infinium, which in turn creates the internet. Ethernet uses a system called CSMA/CD or Carrier Sense Multiple Access with Collision Detection. This system is able to deal with collisions which happen when two messages are sent at the same time. When two nodes on a network attempt to exchange data at the same time, they collide and create an error. When this happens, all nodes involved are notified. The Ethernet protocol will then set a random time interval, after which the node will re-attempt the transmission. This will be done until the message is successfully sent. Just as the hypertext transfer protocol and transmission control protocols will be used every single time a student at PCO’s learning centre accesses internet, so too is the ethernet protocol. This, however, will be done in a slightly different way. As the students will be using Wi-Fi to connect to the modem, ethernet will not be used. In saying this, ethernet will be used to connect to the NAS and the printer. For example, if two students want to print something, and they do so at the exact same time, the messages will collide. As the printer is connected through ethernet, the printer, and two computers will be notified of the collision. The ethernet protocol will then set a random time interval, and the printing request will be sent again at different times for each computer. Although this is a reasonably complex process, in real time, the students will have no idea this is happening, and the printer will print both students documents like nothing has
Meanwhile, the advent of early PC’s and the recognition of the value in networking devices together gave rise to Local Area Networks. These LAN’s were developed from a business customer perspective, which placed more emphasis on costs and ease of use over reliability. There were a number of different competing LAN technologies, two of the most common being Token Ring (IBM) and Ethernet (everyone else). The triumph of Ethernet in the marketplace, to the extent where it is included in every PC, game console and some refrigerators, provides a consistent and relatively inexpensive way to build internal networks with relative ease.
All computers are connected to a hub, switch or router. Require more cabling, but failure of one node does not break down the network.
Token ring networks have since declined in usage and the standards activity has since come to a standstill as switched Ethernet has dominated the LAN/layer 2 networking market.
Traditional Ethernets, in which all hosts compete for the same bandwidth, are called shared Ethernets. Switched Ethernets are becoming very popular because they are an effective and convenient way to extend the bandwidth of existing Ethernets.
Switches, which are layer 2 devices, use decision based routing by storing NIC hardware addresses and port numbers on a table in the switch. By doing this, when data is received by the switch, it knows where the source was, and where the data needs to go. This allows for faster data transmission for all NICS that are connected, because it uses the swi...
It can also be noted that there is a significant amount of the broadcast packets like ARP, NBNS and UDP, as shown in figure 4.6 a partial segment of the Wireshark output and due to these packets the switches should experience a vast number of broadcasts, which in general degrades the entire network performance.
The Ethernet has been around for several decades and is a mature data transfer mechanism based on packets and internet protocol (IP). Its main focus has always been the LANs and transfer of data. ATM is a recent technology that many thought would replace Ethernet as the technology of choice. It can transfer data, voice and video at a much higher rate of speed than Ethernet. So why hasn't ATM replaced Ethernet? In a world where everyone wants everything faster and more efficient, ATM should be the hands-down choice for a networking service. However, it's not as simple as that. Reviewing the advantages and disadvantages of each should be very revealing as to who has the upper hand in network technologies.
It just doesn't get much simpler than the physical bus topology when it comes to connecting nodes on a Local Area Network (LAN). The most common implementation of a linear bus topology is IEEE 802.3 Ethernet. All devices in a bus topology are connected to a single cable called the bus, backbone, or ether. The transmission medium has a physical beginning and an end. All connections must be terminated with a resistor to keep data transmissions from being mistaken as network traffic. The terminating resistor must match the impedance of the cable.
Next, the writer goes over the second type of network architecture - the TCP/IP reference model, the granddaddy of the wide area computer network. This architecture allows the connection of multiple networks seamlessly. The architecture is flexible and capable of running even if some of the subnet hardware is destroyed or non-functional as long as the source and destination machines are functioning. In a similar fashion to the OSI model, the TCP/IP model has layers as well. In this case, we have four layers: the link
During the silent period of the communication when the users are not utilizing the bandwidth than this idle bandwidth cannot be used by the other parties as a result this bandwidth gets wastes.
LANs systems can be defined and connected in many different ways. This is the reason for the standardization for every one can have a common ground to start from. “The LANs described Herein are distinguished from other types of data networks in that they are optimized for a moderate size geographic area such as a single office building, warehouse, or a campus. The IEEE 802 LAN is a shared medium peer-to-peer communications network that broadcasts information for all stations to receive. As a consequence, it does not inherently provide privacy. The LAN enables stations to communicate directly using a common physical medium on a point-to-point basis without any intermediate switching node being required. There is always need for an access sublayer in order to arbitrate to access to the shared medium. The network is generally owned, used, and operated by a single organization. This is in contrast to Wide Area Networks (WANs) that interconnect communication facilities in different parts of a country or are used as a public utility. These LANs are also different from networks, such as backplane buses, that are optimized for the interconnection of devices on a desk top or components within a single piece of equipment.”(IEEE 802 Standard 1990) That is the standard definition for LANs by Institute of Electrical and Electronics Engineer committee 802. They are the committee used to set the standard in workmanship and operations for technicians that set-up and perform maintenance on LANs systems. And through all the technical words what they are trying to say is a LAN is a small area network that distributes information among computer in a small work environment unlike WANs that distribute information across global areas.