CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 27 ppt

Workstation and Server Relationships 229 Figure 4-41 Client-Server Model Servers are designed to handle requests from many clients simultaneously, as shown in Figure 4-42. Before a client can access the server resources, the user must be identified and be authorized to use the resource. You handle this authorization by assigning each user an account name and password that is verified by an authentication service acting as a sentry to guard access to the network. By centralizing user accounts, security, and access control, server-based networks simplify the work of network administration. The concentration of network resources such as files, printers, and applications on servers also makes the data they generate easier to back up and maintain. Rather than having these resources spread around individual machines, they can be located on specialized, dedicated servers for easier access. Most client-server systems also include facilities for enhancing the network by adding new services that extend the usefulness of the network. The distribution of functions in client-server networks brings substantial advantages, but it also incurs some costs. Although the aggregation of resources on server systems brings greater security, simpler access, and coordinated control, the server introduces a single point of failure into the network. Without an operational server, the network cannot function at all. Servers require a trained, expert staff to administer and main- tain. This requirement increases the expense of running the network. Server systems also require additional hardware and specialized software that add to the cost. Computer Computer Computer Computer Peer-to-Peer Environment Workstation Workstation Workstation Client-Server Environment Server Mainframe Environment Mainframe chpt_04.fm Page 229 Tuesday, May 27, 2003 9:01 AM 230 Chapter 4: Cable Testing and Cabling LANs and WANs Figure 4-42 Server Resources Tables 4-4 and 4-5 summarize the advantages and disadvantages of peer-to-peer versus client-server. Table 4-4 Peer-to-Peer/Client-Server Advantages Advantages of a Peer-to-Peer Network Advantages of a Client-Server Network Less expensive to implement. Provides for better security and scalability. Does not require NOS server software. Easier to administer when the network is large because administration is centralized. Does not require a dedicated network administrator. All data can be backed up on one central location. chpt_04.fm Page 230 Tuesday, May 27, 2003 9:01 AM Cabling the WAN 231 Cabling the WAN To connect one network to other remote networks, it is sometimes necessary to utilize wide-area network (WAN) services. WAN services provide different connection methods, and the cabling standards differ from those of LANs. Therefore, it is therefore to for you to understand the types of cabling needed to connect to these services. This section explains the cabling and connectors that are used to interconnect switches and routers in a LAN or WAN. This section also discusses how to cable routers for serial connection, Integrated Services Digital Network Basic Rate Interface (ISDN BRI) connection, digital subscriber line (DSL) connection, and cable connection, as well as how to set up console connection. Table 4-5 Peer-to-Peer/Client-Server Disadvantages Disadvantages of a Peer-to-Peer Network Disadvantages of a Client-Server Network Does not scale well to large networks and administration becomes unmanageable. Requires NOS software such as in Windows NT/2000/XP, Novell NetWare, or UNIX. Each user must be trained to perform administrative tasks. Requires expensive, more powerful hard- ware for the server machine. Less secure. Requires a professional administrator. All machines sharing the resources negatively impact the performance. Has a single point of failure if there is only one server, and user’s data can be unavailable if the server is down. Lab Activity Building a Hub-Based Network In this lab, you create a simple network between two PCs using an Ethernet hub. You identify and locate the proper cables, configure workstation IP addresses, and test connectivity using the ping command. Lab Activity Building a Switch-Based Network In this lab, you create a simple network between two PCs using an Ethernet switch. You identify and locate the proper cables, configure workstation IP addresses, and test connectivity using the ping command. chpt_04.fm Page 231 Tuesday, May 27, 2003 9:01 AM 232 Chapter 4: Cable Testing and Cabling LANs and WANs WAN Physical Layer Many physical implementations carry traffic across the WAN. Needs vary, depending on the distance of the equipment from the services, the speed, and the actual service itself. Figure 4-43 lists a subset of data link and physical implementations that support some of the more prominent WAN solutions today. The type of physical layer you choose depends on the distance, speed, and the type of interface you need to connect. Figure 4-43 WAN Physical Layer Implementations Serial connections are used to support WAN services such as dedicated leased lines that run the Point-to-Point Protocol (PPP) or Frame Relay. The speed of these connections ranges from 2400 bps to T1 (1.544 Mbps). Other WAN services, such as the ISDN, offer dial-on-demand connections or dial- backup services. An ISDN BRI is composed of two 64-kbps bearer channels (B channels) for data, and one delta channel (D channel) at 16 kbps used for signaling and other link-management tasks. PPP typically is used to carry data over the B channels. The increasing demand for residential broadband (high-speed) services has increased the popularity for DSL and cable modem connections. DSL service can achieve T1/E1 speeds over the existing telephone line. Cable services, which work over the existing coaxial cable TV line, also offer high-speed connectivity matching or surpassing that of DSL. WAN Serial Connections Serial transmission is a method of data transmission in which bits of data are transmitted sequentially over a single channel. This one-at-a-time transmission contrasts with parallel data transmission, which transmits several bits at a time. For long-distance communication, WANs use serial transmission. To carry the energy represented in bits, serial channels use a specific electromagnetic or optical frequency range. chpt_04.fm Page 232 Tuesday, May 27, 2003 9:01 AM Cabling the WAN 233 Frequencies, described in terms of their cycles per second (hertz), function as a band or spectrum for communication. For example, the signals transmitted over voice-grade telephone lines use up to 3 kHz (kilohertz, or thousand hertz). The size of this frequency range is called the bandwidth. Another way to express bandwidth is to specify the amount of data in bits per second that the serial channel can carry. Table 4-6 compares physical standards for EIA/TIA-232 and EIA/TIA-449, v.35, X.21, and EIA-530 WAN serial connection options. Several types of physical connections enable you to connect to serial WAN services. You must select the correct serial cable type to use with the router, depending on the physi- cal implementation that you choose or the physical implementation that your service provider imposes. Figure 4-44 shows all the different serial connector options available. Serial connectors are used to connect end-user devices and service providers. Note that serial ports on Cisco routers use a proprietary 60-pin connector or smaller “smart serial” connector, which enables two serial connections on a WAN interface card. The type of connector on the other end of the cable is dependent on the service provider or end-device requirements, but V.35 is quite common. Table 4-6 Comparison of Physical Standards Data (bps) Distance (Meters) EIA/TIA-232 Distance (Meters) EIA/TIA-449, V.35, X.21, EIA-530 2400 60 1250 4800 30 625 9600 15 312 19,200 15 156 38,400 15 78 115,200 3.7 — T1 (1.544 Mbps) — 15 chpt_04.fm Page 233 Tuesday, May 27, 2003 9:01 AM 234 Chapter 4: Cable Testing and Cabling LANs and WANs Figure 4-44 WAN Serial Connection Options Routers and Serial Connections In addition to determining the cable type, you need to determine whether you need data terminal equipment (DTE) or data communications equipment (DCE) connectors for your equipment. The DTE is the endpoint of the user’s device on the WAN link. The DCE is the device used to convert the user data from the DTE into a form acceptable to the facility providing WAN services. As shown in Figure 4-45, if connecting directly to a service provider or to a device that performs signal clocking (such as a channel service unit/data service unit [CSU/DSU]), the router is a DTE and needs a DTE serial cable. This situation is typically the case for routers. Figure 4-45 Serial Implementation of DTE and DCE N O TE Clocking is a method used to synchronize data transmission between devices. In a WAN serial connec- tion, the CSU/DSU controls the clocking of the transmitted data. Data Terminal Equipment: Data Communications Equipment: chpt_04.fm Page 234 Tuesday, May 27, 2003 9:01 AM Cabling the WAN 235 However, in some cases the router must be the DCE, as shown in Figure 4-46. For example, if performing a back-to-back router scenario (meaning that routers are used at both ends of the connection) in a test environment, one of the routers is a DTE, and the other is a DCE to provide the clock. Figure 4-46 Back-to-Back Serial Connection When you are cabling routers for serial connectivity, the routers have either fixed or modular ports. The type of port being used affects the syntax that you use later to con- figure each interface. Figure 4-47 shows an example of a router with fixed serial ports (interfaces). Each port is given a label of port type and port number—for example, serial 0. To configure a fixed interface, you specify the interface using the port type and port number convention— for example, Serial 0. Figure 4-47 Fixed Interfaces Figure 4-48 shows examples of routers with modular serial ports. Usually, each port is given a label of port type, slot (the location of the module), and port number. To configure a port on a modular card, you are asked to specify the interface using the convention “port type slot number/port number”—for example, serial 1/0, in which the type of interface is a serial interface, the slot number where the serial interface module is installed is slot 1, and the specific port that you are referencing on that serial interface module is port 0. Ethernet AUI LED Synchronous Serial LEDs System OK LED Power On/Off Switch AUX Port BRI Port Synchronous Serial Port (DB-60) Console Port Ethernet AUI Port (DB-15) chpt_04.fm Page 235 Tuesday, May 27, 2003 9:01 AM 236 Chapter 4: Cable Testing and Cabling LANs and WANs Figure 4-48 Modular Serial Port Interfaces Routers and ISDN BRI Connections With ISDN BRI, you can use two types of interfaces: BRI S/T and BRI U. In ISDN BRI service, a user (U) interface is the electrical interface for the twisted-pair wire connec- tion from a user to a Network Termination 1 (NT1) device. A terminal (T) interface is the electrical interface between an NT1 device and an NT 2 device, which is usually a private branch exchange (PBX). A system (S) interface is the electrical interface between an NT1 and ISDN devices such as a computer or a telephone. In BRI, the T interface is electrically identical to the S interface. Thus, the two interfaces are typically combined in a single interface, referenced as an S/T interface. To determine which interface type you need, you must find out whether you or the ser- vice provider provides an NT1 device. An NT1 device is an intermediate device between Lab Activity Connecting Router LAN Interfaces In this lab, you identify the Ethernet or Fast Ethernet interfaces on the router. Then identify and locate the proper cables to connect the routers to hubs or switches. Finally, use the cables to connect the router and computers to the hub or switch. Lab Activity Building a Basic Routed WAN In this lab, you connect two simple LANs, each consisting of a workstation and a switch (or hub), to form a basic router-to-router WAN. chpt_04.fm Page 236 Tuesday, May 27, 2003 9:01 AM Cabling the WAN 237 the router and the service-provider ISDN switch (cloud) that is used to connect four- wire subscriber wiring to the conventional two-wire local loop. In North America, the customer typically provides the NT1; in the rest of the world, the service provider pro- vides the NT1 device. If the NT1 device needs to be provided by the customer, an ISDN BRI with a U interface can be used. A U interface has an NT1 built in. If an external NT1 device is used or if the service provider uses an NT1 device, the router needs an ISDN BRI S/T interface. Because routers can have multiple ISDN interface types, the interface needed must be determined when the router is purchased. Some routers have both a U and an S/T interface. The type of ISDN connector that the router has can be determined by look- ing at the port label. Figure 4-49 shows the different port types for the ISDN interface. Figure 4-49 Cabling Routers for ISDN Connections To interconnect the ISDN BRI port on the router to the service-provider device, use a UTP CAT 5 straight-through cable with RJ-45 connectors. Note that the ISDN BRI cable pinouts are different than the pinouts for Ethernet. Table 4-7 shows the ISDN BRI S/T interface connector pinouts. CAUTION It is important to insert a cable running from an ISDN BRI port only to an ISDN jack or an ISDN switch. ISDN BRI uses voltages that can seriously damage non-ISDN devices. chpt_04.fm Page 237 Tuesday, May 27, 2003 9:01 AM 238 Chapter 4: Cable Testing and Cabling LANs and WANs Routers and DSL Connections DSL technology is a modem technology that enables inexpensive, high-speed digital transmission over existing twisted-pair telephone lines. For most small offices or home offices today, DSL technology is a good choice for many business applications, such as file transfer and access to a corporate intranet. Asymmetric digital subscriber line (ADSL) is the most common and is part of a larger family of technologies generically referred to as xDSL. The Cisco 800 series of fixed-configuration DSL routers provides enhanced security, low cost of ownership, proven reliability, and safe investment through the power of Cisco IOS Software tailored for small offices and telecommuters. The Cisco 827-4V ADSL router has one ADSL interface, as shown in Figure 4-50, that can connect users to the Internet or to a corporate LAN via DSL. Figure 4-50 Cisco 827-4V Router Table 4-7 ISDN BRI S/T Interface Connector Pinouts Pin Signal 1 Unused 2 Unused 3 Transmit (Tx+) 4 Receive (Rx+) 5 Receive (Rx-) 6 Transmit (Tx-) 7 Unused 8 Unused chpt_04.fm Page 238 Tuesday, May 27, 2003 9:01 AM . Physical Standards Data (bps) Distance (Meters) EIA/TIA -23 2 Distance (Meters) EIA/TIA-449, V.35, X. 21 , EIA-530 24 00 60 12 50 4800 30 625 9600 15 3 12 19 ,20 0 15 15 6 38,400 15 78 11 5 ,20 0 3.7 — T1 (1. 544. Environment Mainframe chpt_04.fm Page 22 9 Tuesday, May 27 , 20 03 9: 01 AM 23 0 Chapter 4: Cable Testing and Cabling LANs and WANs Figure 4- 42 Server Resources Tables 4-4 and 4-5 summarize the advantages and disadvantages. You identify and locate the proper cables, configure workstation IP addresses, and test connectivity using the ping command. chpt_04.fm Page 2 31 Tuesday, May 27 , 20 03 9: 01 AM 23 2 Chapter 4: Cable