Network Protocols
Protocols are the rules by which network operate. They set the standards for error detection, control sequence, message lengths, media access and so on. All networks must use a protocol and, in general, the protocol must be common to all nodes on the network. The following paragraphs offer a quick review of three of the major protocols in use today, NetBEUI, IPX/SPX and TCP/IP.
NETBEUI
NEtBEUI (NetBIOS extended user interface) is an enhanced version of the NetBIOS(network basic input/output system) protocol and was developed when computer networking primarily meant local area networking for a relatively small number of computers,from two computers to about 200. It was not developed to take into account enterprise networks where frames are directed from one network to another through routing and routers. For this reason, NetBEUI is well suited for small local area networks(LANs).
IPX/SPX
IPX/SPX (Internet packet exchange/sequenced packet exchange) is the protocol stack (several layers of software that define the protocol)used primarily by Novell Netware. One advantage it has over NetBEUI is that it has routing capabilities, so data can be transported over multiple networks. A companion protocol is SPX which enables the exchange of application specific data with greater reliability than IPX.
TCP/IP
TCP/IP (transmission control protocol/Internet protocol) is a protocol stack and is the communications protocol used on the Internet. If your LAN will be connected to the Internet you will need to enable TCP/IP protocol. Before setting up TCP/IP, you will need to make a decision about how to set up IP addressing on the network. The options are to use either static addressing or dynamic addressing.. Static addressing involves assigning a unique IP address to each workstation permanently. Dynamisc addressing automatically assigns an IP address to s computer each time it is logged on: this method is called dynamic host configuration protocol (DHCP).TCP/IP is well suited to medium to large networks. It is designed for routing, is highly reliable and offers better security than NetBEUI. The size of the protocol suite is large and hence its implementation on MS-DOS machines is difficult, especially the older ones. The other disadvantage is the slow speed of the protocol because of high implementation overheads.
Network hardware
When we refer to network hardware we are talking about a range of electronic devices that can be interconnected in such a way as to allow the transmission of communication signals between a number of workstations. These devices range from simple generic hubs to sophisticated proprietary hardware such as routers and gateways. To help gain a better understanding of how these devices interact with each other you need a knowledge of what devices are available and how they work.
The following represents some of the more commonly used network hardware components.
Network interface cards
Network interface cards(NICs) are the most common type of network hardware on a network. Every workstation and server will contain at least one NIC. NICs contain the electronic components that establish and control network communications. The NIC is the principle hardware device that differentiates between a networked computer and a stand –alone computer.
Transmission media
The transmission media or cables are the most important component of a network; after all, it is the cables that provide the physical connections between the workstations and that server. There are several different types of cable that can be used in networking and, although many networksuse a particular cable type exclusively, increasingly more and more networks are using a combination of different cable types. The choice of cable for your network needs to be considered carefully, as different cable s not only transmit at different speeds but also have different distance limitations. The two most common cable types used in modern networks are coaxial cable and twisted pair.
Hubs
Hubs are one of the most basic pieces of networking equipment available. Physically a hub is a box with a number of RJ45 ports(typically between 4 and 32) that allows you to connect several networking devices together using twisted pair (CAT 5) network cables.
Routers, switches and bridges
Switches look nearly identical to hubs, but a switch generally contains more intelligence than a hub. Unlike hubs,network switches are cable of inspecting the data packets as they are received, determining the source and destination device of tht packet, and forwarding that packet appropriately. By delivering messages only to connected device that it was intended for,network switches concerve network band width and offer generally better performance than hubs. Most switches are active: that is, they electrically amplify the signal as it moves from one device to another.
Bridges are devices that allow you to segment a large network into two smaller, more efficient networks. If you are adding to an older wiring scheme and want the new network to be up-to- date, a bridge can connect the two.
Routers translate information from one network to another; it is similar toa bridge with extra intelligence. Routers select the best path to route a message, based on the destination address and origin. The router can direct traffic to prevent head-on collisions, and is smart enough to know when to direct traffic along back roads and shortcuts.
Protocols are the rules by which network operate. They set the standards for error detection, control sequence, message lengths, media access and so on. All networks must use a protocol and, in general, the protocol must be common to all nodes on the network. The following paragraphs offer a quick review of three of the major protocols in use today, NetBEUI, IPX/SPX and TCP/IP.
NETBEUI
NEtBEUI (NetBIOS extended user interface) is an enhanced version of the NetBIOS(network basic input/output system) protocol and was developed when computer networking primarily meant local area networking for a relatively small number of computers,from two computers to about 200. It was not developed to take into account enterprise networks where frames are directed from one network to another through routing and routers. For this reason, NetBEUI is well suited for small local area networks(LANs).
IPX/SPX
IPX/SPX (Internet packet exchange/sequenced packet exchange) is the protocol stack (several layers of software that define the protocol)used primarily by Novell Netware. One advantage it has over NetBEUI is that it has routing capabilities, so data can be transported over multiple networks. A companion protocol is SPX which enables the exchange of application specific data with greater reliability than IPX.
TCP/IP
TCP/IP (transmission control protocol/Internet protocol) is a protocol stack and is the communications protocol used on the Internet. If your LAN will be connected to the Internet you will need to enable TCP/IP protocol. Before setting up TCP/IP, you will need to make a decision about how to set up IP addressing on the network. The options are to use either static addressing or dynamic addressing.. Static addressing involves assigning a unique IP address to each workstation permanently. Dynamisc addressing automatically assigns an IP address to s computer each time it is logged on: this method is called dynamic host configuration protocol (DHCP).TCP/IP is well suited to medium to large networks. It is designed for routing, is highly reliable and offers better security than NetBEUI. The size of the protocol suite is large and hence its implementation on MS-DOS machines is difficult, especially the older ones. The other disadvantage is the slow speed of the protocol because of high implementation overheads.
Network hardware
When we refer to network hardware we are talking about a range of electronic devices that can be interconnected in such a way as to allow the transmission of communication signals between a number of workstations. These devices range from simple generic hubs to sophisticated proprietary hardware such as routers and gateways. To help gain a better understanding of how these devices interact with each other you need a knowledge of what devices are available and how they work.
The following represents some of the more commonly used network hardware components.
Network interface cards
Network interface cards(NICs) are the most common type of network hardware on a network. Every workstation and server will contain at least one NIC. NICs contain the electronic components that establish and control network communications. The NIC is the principle hardware device that differentiates between a networked computer and a stand –alone computer.
Transmission media
The transmission media or cables are the most important component of a network; after all, it is the cables that provide the physical connections between the workstations and that server. There are several different types of cable that can be used in networking and, although many networksuse a particular cable type exclusively, increasingly more and more networks are using a combination of different cable types. The choice of cable for your network needs to be considered carefully, as different cable s not only transmit at different speeds but also have different distance limitations. The two most common cable types used in modern networks are coaxial cable and twisted pair.
Hubs
Hubs are one of the most basic pieces of networking equipment available. Physically a hub is a box with a number of RJ45 ports(typically between 4 and 32) that allows you to connect several networking devices together using twisted pair (CAT 5) network cables.
Routers, switches and bridges
Switches look nearly identical to hubs, but a switch generally contains more intelligence than a hub. Unlike hubs,network switches are cable of inspecting the data packets as they are received, determining the source and destination device of tht packet, and forwarding that packet appropriately. By delivering messages only to connected device that it was intended for,network switches concerve network band width and offer generally better performance than hubs. Most switches are active: that is, they electrically amplify the signal as it moves from one device to another.
Bridges are devices that allow you to segment a large network into two smaller, more efficient networks. If you are adding to an older wiring scheme and want the new network to be up-to- date, a bridge can connect the two.
Routers translate information from one network to another; it is similar toa bridge with extra intelligence. Routers select the best path to route a message, based on the destination address and origin. The router can direct traffic to prevent head-on collisions, and is smart enough to know when to direct traffic along back roads and shortcuts.
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