| Part of the role of the network administrator is to expand the network to include new client systems. Many factors are required to connect a client to the network including media, protocols, and services. This section explores the requirements to connect a client system to an existing network. Choosing a NIC A client system cannot access the network if it does not have a network card installed. There are several factors to consider when selecting a network card: Bus compatibility Some older systems have only Industry Standard Architecture (ISA) slots, but most modern systems have either Peripheral Component Interconnect (PCI) slots or both PCI and ISA slots. Either way, you should verify that there is an expansion slot of the correct type available. Wireless NICs can be installed using a USB adapter. Type of network As mentioned in the discussion on NICs in Chapter 3, "Networking Devices," unless you are using a networking system other than Ethernet, you should not need to specify another type of NIC. The exception here is if the client system is being attached using a wireless connection. A Wireless NIC would then be required. Media compatibility Modern LANs use NICs that support UTP cable. There are some out there, however, that still require coaxial connectors and more modern ones might have fiber connectors.
Besides these criteria, which dictate to a certain extent which NICs you can use, the choice then depends on manufacturer, cost, and requirements. The NIC might come preinstalled in the system or, as in an increasing number of cases, the NIC might be built on to the system board. In either of these situations, you do not have to install a NIC. Media With the NIC installed and functioning, the next step is to connect the PC to the network via network media. This can be simple or complicated, depending on the type of network you are using. The following are some of the factors you should consider when connecting a new system to an existing network: Connecting to a coaxial network The biggest considerationwhen connecting to a coaxial network is that it might be necessary to break the coaxial segment to insert a Bayonet Neill Concelman (BNC) T-connector to physically connect the PC. Unfortunately, breaking a coaxial cable segment prevents any device connected to it from working. This means that if you are adding a computer to a coaxial segment and you need to add a length of cable and a connector, you need to either arrange with network users for a few minutes when the network will be unavailable or add the cable and connector before or after working hours. The good news is that you can leave spare BNC T-connectors in the coaxial cable segment as a just-in-case precaution. Doing so can mean that you can add a system to the coaxial segment without affecting users other than the one whose system you are connecting. Connecting to a twisted-pair network Twisted pair is the easiest of all the network types to connect to. All you need to connect is a cable (referred to as a patch cable) that connects the system to a hub or switch. In environments that use a structured cable system, the cable can be connected to a wall jack or a jack in a floor box. In a less structured environment, the cable can be run directly between the system and the hub or switch. One item worthy of note is that if you are using a Token Ring network, you must configure the NIC to work at the correct speed. Twisted-pair Ethernet networks can accommodate different speeds if the networking hardware supports a speed higher than the base 10Mbps. Token Ring networks do not offer this function; all devices on the ring must operate at the same speed (4Mbps or 16Mbps). Connecting a system to the network with a NIC configured for the wrong speed prevents the system from communicating on the network, and it might even cause problems with other devices on the segment. Connecting to a wireless network Wireless network connections use radio frequency instead of traditional wire. Connecting a wireless client requires a wireless access point, which provides a bridge between a wired network and the wireless network segment. Wireless standards use RF frequencies of 2.4GHz for 802.11b/g and 5GHz for 802.11a. The wireless client also requires the SSID of the wireless access point and the security settings to connect. Once connected, the wireless client can access the wired network through the AP.
After the physical connection to the network has been established, you need to consider the network protocols to use. Choosing LAN Protocols Choosing the correct protocol is an important consideration when configuring a network or adding systems to an existing network. The client and the server must use the same protocol in order for communication to take place. This section provides a brief summary of the commonly used protocols. For a complete description of the various protocols, refer to Chapter 4, "OSI Model and Network Protocols." TCP/IP By far the most prevalent of network protocol suites, TCP/IP is available for almost every computing platform and has widespread industry support. The majority of LANs now use TCP/IP as the default protocol. Configuring TCP/IP connectivity requires the use of an IP address, a subnet mask, a default gateway, and possibly Domain Name Service (DNS) server information and Windows Internet Naming System (WINS) information. IPX/SPX Novell invented and implemented IPX/SPX when it introduced NetWare in the 1980s. At that time, TCP/IP was for the most part an academic/military/government protocol, and Novell realized the need for a robust, routable protocol. IPX/SPX is one of the main reasons that Novell owned the networking market through the 1980s and most of the 1990s. IPX/SPX was also easy to install and configure. Today, TCP/IP has largely displaced IPX. One of the advantages of IPX is that workstation configuration is very simple. Generally speaking, the only item that might need to be configured is the frame type, which determines the format in which data is grouped into the frames that are placed on the network. Older versions of NetWare use a frame type called 802.3, whereas newer versions use a frame type called 802.2. Fortunately, most client software is capable of detecting the frame type automatically. AppleTalk AppleTalk is aprotocol associated with Apple networks. The AppleTalk protocol is an established protocol suite having been introduced in the early 1980s, it soon became a viable internetworking protocol. Similar to the IPX/SPX and TCP/IP protocol suites, the AppleTalk protocol suite is composed of several protocols. NWLink When Microsoft began working on adding support for interoperability with NetWare, it opted to develop its own fully compatible version of Novell's proprietary IPX/SPX. This development was necessary because earlier versions of NetWare did not support authentication over TCP/IP.  | On the Network+ exam, be careful when determining whether connectivity to a NetWare server is required from a Microsoft client. NWLink is the required protocol because Microsoft does not directly support IPX/SPX. Watch for this same situation in reverse as well: NetWare uses IPX/SPX to communicate with a Windows Server running NWLink. |
NetBEUI Microsoft chose IBM's NetBEUI as the protocol for its first networking implementation in the mid-1980s. One of the reasons Microsoft chose to base its early networking efforts on NetBEUI was the protocol's simplicity and speed. Microsoft wanted to offer a very simple, easy workgroup configuration. Name resolutions and network addressing, or more accurately naming, are both handled automatically with NetBEUI. There are no configuration issues, other than setting up the NIC and installing NetBEUI as the protocol. Because of NetBEUI's simplicity, administrators sometimes use it to troubleshoot hard-to-find communication problems between two machines. The simplicity of NetBEUI also created problems for Microsoft as the 1980s progressed. NetBEUI is a non-routable protocol, and as networks began to interconnect, Microsoft found its clients stranded within the confines of small LANs.
As mentioned earlier, TCP/IP is by far the most common of the networking protocols in use today. For that reason, the next section takes a more in-depth look at configuring client systems to use TCP/IP. Configuring Client Systems for TCP/IP In a TCP/IP network, there are several settings to configure to enable a client system to access peer and server services. Configuring a client system for TCP/IP can be a relatively complex task, or it can be simple. Any complexity involved is related to the possible need to configure TCP/IP manually. The simplicity is related to the fact that TCP/IP configuration can occur automatically via DHCP. Brief explanations of the IP related settings used to connect to a TCP/IP network follow: IP address Each system must be assigned a unique IP address so that it can communicate on the network. Subnet mask The subnet mask enables the system to determine which portion of the IP address represents the network address and which portion represents the node address. Default gateway The default gateway enables the system to communicate with systems on a remote network, without the need for explicit routes to be defined. DNS server addresses DNS servers enable dynamic hostname resolution to be performed. It is common practice to have two DNS server addresses defined so that if one server becomes unavailable, the other can be used. WINS server addresses A WINS server enables Network Basic Input/Output System (NetBIOS) names to be resolved to IP addresses. As with DNS servers, it is common practice to enter two WINS server addresses to provide a degree of fault tolerance.
| At the very minimum, an IP address and a subnet mask are required to connect to a TCP/IP network. With just this minimum configuration, connectivity is limited to the local segment, and DNS and WINS resolution are not be possible. |
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