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

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 connecti

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

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

Workstation

Workstation

Data Stored on One Server

Workstation

Workstation

Data Distributed Across Multiple Servers

Server Server

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.

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 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

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 physiphysi-cal 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

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

NOTE

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.

S S S

S S S

Data Terminal Equipment:

- End of the UserÕs Device

on the WAN Link

Data Communications Equipment:

- End of the WAN ProviderÕs Side of the Communication Facility

- Responsible for Clocking

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

5 ,+-

5 ,6-

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)

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 Terminaconnec-tion 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 deser-vice An NT1 deser-vice is an intermediate deser-vice 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

the router and the service-provider ISDN switch (cloud) that is used to connect

four-wire subscriber wiring to the conventional two-four-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.

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