[ad_1]
When computer networks are working well, which we hope is most of the time, the inner workings of the system modules are transparent to the average user. The most common elements on the network, not counting cables, are “way”, “hubs”, and “switches”. Many of these modules can be similar cosmetically. Each assembly typically has Ethernet connectors (RJ45, which looks like an oversized telephone plug) and LED indicators. However, these modules function differently, and it is important to understand the difference.
Modern network hardware operates on the “Open System Interconnection” (OSI) standard. This standard specifies how communication network should be implemented. By accordance with this standard, modules from different manufacturers can coexist on the same network. Wireless Internet (WiFi) and 802.11x standard are more a subset of networks.
When a message is sent between computers, it is broken into pieces. At the base level, the message is reduced to “1” and “0” bits. The next level is a group of bits called a “frame”. A frame contains its control information, including target address and error detection. The next level is a group of frames called a “packet”. The terms frame and packet are sometimes used interchangeably. If a message is sent on a complex network like the Internet, some packages may take a different path, and recombined at the destination.
Error detection is used with both frames and packets. The most common routine is called “Cyclic Redundancy Check” (CRC). CRC sums of all “1” s in the frame or packet. This number is stored as a hexadecimal value at the end of the frame / packet. On the receiving end, the process is repeated. If the two hexadecimal values agree, the test passes. If not, the receiving device requests that the sending device resend. Most of this functionality is performed by integrated circuits (chips) inside the network modules.
The Hub
The network hub operates on the first layer of the OSI standard, called the “physical layer”. The center is the simplest of the three units. A hub is not aware of the contents of the messages processed; that the message bits. It simply records the signal, and rebroadcast it to all, including back to the port from which the message. An “active” hub will clean the electrical signal of noise and amplify signals before broadcast. A “passive” hub does not amplify the signal; she just gets the signal, and rebroadcast the signal as received to each port. Hubs are sometimes used to connect multiple computers with a printer.
The Network Switch
The network switch operates on the second layer of the OSI standard, called the “data link layer”. The network switch, as the name suggests, the switch signal paths, so that a message frame goes to a specific destination. A switch will improve the network performance, especially on networks with many computers. A switch has enough on board intelligence to remember the path to each destination. The network switch the message frame.
When you connect the computer to a network switch, the switch registers the Media Access Control or “Mac” address of the network interface card in the computer (NIC). This is called address protocol, or “ARP”. When a frame is received intended for a specific computer, the switch sent the frame only to that computer. By inhibiting mechanisms of the network from being utilized by every frame, network resources preserved. Computer A can send a frame to computer B, while simultaneously, computer C is sending a frame to computer D.
The Network Router
The network router operates on the third layer of the OSI standard, called “network layer”. Name router is also indicative of its role. Routers have some of the same capabilities as switches, but routers are typically used to connect two or more networks. For example, a way could be used to connect a wireless network with a conventional local area network (LAN). Another common use is to connect the LAN with the Internet (a “wide-area network”, or “WAN”). In this role, the router uses “Network Address Translation” (NAT) so that all computers attached to networks share a single IP address. A network router handles the message in packets. A router uses the IP addresses in the packet to dispose of them between multiple networks.
A personal computer can be configured to deal with the role of the router if it is equipped with router software and two or more network interface cards (NIC). A separate NIC is needed for each network.
A router is capable of advanced functions, including serving as DHCP (domain host control protocol) server and firewall. A Firewall protects computers from potential hazards from the other computers outside the network. Linking multiple networks often requires the conversion of protocols.
A router is an extremely diverse classification. Routers may provide connectivity inside offices, between different locations, and between businesses and the Internet. Largest way connect Internet service providers, are used in very large enterprise networks, or affiliate company of satellite distant corporate site. Advanced routers are powerful computers, complete with microprocessors. Very sophisticated routers are used by the Internet to manage the network traffic most efficiently.
directly, but a table called “routing information base” (RIB) that tracks information about the available routes. The RIB can be static (manually determined by a network administrator) or dynamic (continually updated to changing circumstances). A RIB is simple on a small LAN, but can be very complex in a very large way used Internet.
Summary
There are more types of network modules than the three discussed here, and there can be significant overlap in roles. For example, “intelligent hub” We have many characteristics of a network switch. Wireless network (WAN) have much in common with conventional LAN cousins, but additional protocol is added for the special security and interference concerns specific to wireless networks. Many functions can be combined into one assembly. Network routers sometimes have subassemblies that function as network switches.
[ad_2]