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
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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.
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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.
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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.
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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
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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:
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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)
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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.
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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.
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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
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