Module Overview
5.1 Cabling LANs
5.1.1 LAN
physical layer
5.1.2 Ethernet in
the campus
5.1.3 Ethernet
media and connector requirements
5.1.4 Connection
media
5.1.5 UTP
implementation
5.1.6 Repeaters
5.1.7 Hubs
5.1.8 Wireless
5.1.9 Bridges
5.1.10 Swtiches
5.1.11 Host
connectivity
5.1.12
Peer-to-peer
5.1.13
Client/server
5.2 Cabling WANs
5.2.1 WAN
physical layer
5.2.2 WAN serial
connections
5.2.3 Routers and
serial connections
5.2.4 Routers and
ISDN BRI connections
5.2.5 Routers and
DSL connections
5.2.6 Routers and
cable connections
5.2.7 Setting up
console connections
Module: Summary
Module: Quiz
Overview
Even though each
LAN is unique, there are many design aspects that are common to all LANs. For
example, most LANs follow the same standards and use the same components. This
module presents information on elements of Ethernet LANs and common LAN
devices.
There are several
types of WAN connections. They range from dial-up to broadband access and
differ in bandwidth, cost, and required equipment. This module presents
information on the various types of WAN connections.
This module
covers some of the objectives for the CCNA 640-801, INTRO 640-821, and ICND
640-811 exams.
Students who
complete this module should be able to perform the following tasks:
- Identify characteristics of
Ethernet networks
- Identify straight-through,
crossover, and rollover cables
- Describe the function,
advantages, and disadvantages of repeaters, hubs, bridges, switches, and
wireless network components
- Describe the function of
peer-to-peer networks
- Describe the function,
advantages, and disadvantages of client-server networks
- Describe and differentiate
between serial, ISDN, DSL, and cable modem WAN connections
- Identify router serial ports,
cables, and connectors
- Identify and describe the
placement of equipment used in various WAN configurations
5.1
Cabling LANs
5.1.1
LAN physical layer
This page describes
the LAN physical layer.
Various symbols
are used to represent media types. Token Ring is represented by a circle. FDDI
is represented by two concentric circles and the Ethernet symbol is represented
by a straight line. Serial connections are represented by a lightning bolt.
Each computer
network can be built with many different media types. The function of media is
to carry a flow of information through a LAN. Wireless LANs use the atmosphere,
or space, as the medium. Other networking media confine network signals to a
wire, cable, or fiber. Networking media are considered Layer 1, or physical
layer, components of LANs.
Each type of media has advantages and disadvantages. These
are based on the following factors:
- Cable length
- Cost
- Ease of installation
- Susceptibility to interference
Coaxial cable,
optical fiber, and space can carry network signals. This module will focus on
Category 5 UTP, which includes the Category 5e family of cables.
Many topologies
support LANs, as well as many different physical media. Figure shows a subset of physical layer
implementations that can be deployed to support Ethernet.
The next page
explains how Ethernet is implemented in a campus environment.
5.1
Cabling LANs
5.1.2 Ethernet in the campus
This page will
discuss Ethernet.
Ethernet is the
most widely used LAN technology. Ethernet was first implemented by the Digital,
Intel, and Xerox group (DIX). DIX created and implemented the first Ethernet
LAN specification, which was used as the basis for the Institute of Electrical
and Electronics Engineers (IEEE) 802.3 specification, released in 1980. IEEE
extended 802.3 to three new committees known as 802.3u for Fast Ethernet,
802.3z for Gigabit Ethernet over fiber, and 802.3ab for Gigabit Ethernet over
UTP.
A network may
require an upgrade to one of the faster Ethernet topologies. Most Ethernet
networks support speeds of 10 Mbps and 100 Mbps.
The new
generation of multimedia, imaging, and database products can easily overwhelm a
network that operates at traditional Ethernet speeds of 10 and 100 Mbps.
Network administrators may choose to provide Gigabit Ethernet from the backbone
to the end user. Installation costs for
new cables and adapters can make this prohibitive.
There are several
ways that Ethernet technologies can be used in a campus network:
- An Ethernet speed of 10 Mbps
can be used at the user level to provide good performance. Clients or
servers that require more bandwidth can use 100-Mbps Ethernet.
- Fast Ethernet is used as the link
between user and network devices. It can support the combination of all
traffic from each Ethernet segment.
- Fast Ethernet can be used to
connect enterprise servers. This will enhance client-server performance
across the campus network and help prevent bottlenecks.
- Fast Ethernet or Gigabit
Ethernet should be implemented between backbone devices, based on
affordability.
The media and connector requirements for an Ethernet
implementation are discussed on the next page.
5.1
Cabling LANs
5.1.3 Ethernet media and connector
requirements
This page
provides important considerations for an Ethernet implementation. These include
the media and connector requirements and the level of network performance.
The cables and
connector specifications used to support Ethernet implementations are derived
from the EIA/TIA standards. The categories of cabling defined for Ethernet are
derived from the EIA/TIA-568 SP-2840 Commercial Building Telecommunications
Wiring Standards.
Figure compares the cable and connector
specifications for the most popular Ethernet implementations. It is important
to note the difference in the media used for 10-Mbps Ethernet versus 100-Mbps
Ethernet. Networks with a combination of 10- and 100-Mbps traffic use Category
5 UTP to support Fast Ethernet.
The next page
will discuss the different connection types.
5.1 Cabling
LANs
5.1.4 Connection
media
This page
describes the different connection types used by each physical layer
implementation, as shown in Figure . The RJ-45 connector and jack are the most
common. RJ-45 connectors are discussed in more detail in the next section.
The connector on
a NIC may not match the media to which it needs to connect. As shown in Figure
, an interface may exist for the 15-pin attachment unit interface (AUI)
connector. The AUI connector allows different media to connect when used with
the appropriate transceiver. A transceiver is an adapter that converts one type
of connection to another. A transceiver will usually convert an AUI to an
RJ-45, a coax, or a fiber optic connector. On 10BASE5 Ethernet, or Thicknet, a
short cable is used to connect the AUI with a transceiver on the main cable.
The next page
will discuss UTP cables.
5.1 Cabling LANs
5.1.5 UTP implementation
This page
provides detailed information for a UTP implementation.
EIA/TIA specifies
an RJ-45 connector for UTP cable. The letters RJ stand for registered jack and
the number 45 refers to a specific wiring sequence. The RJ-45 transparent end
connector shows eight colored wires. Four of the wires, T1 through T4, carry
the voltage and are called tip. The other four wires, R1 through R4, are
grounded and are called ring. Tip and ring are terms that originated in the
early days of the telephone. Today, these terms refer to the positive and the
negative wire in a pair. The wires in the first pair in a cable or a connector
are designated as T1 and R1. The second pair is T2 and R2, the third is T3 and
R3, and the fourth is T4 and R4.
The RJ-45
connector is the male component, which is crimped on the end of the cable. When
a male connector is viewed from the front, the pin locations are numbered from
8 on the left to 1 on the right as seen in Figure .
The jack, as seen
in Figure , is the female component in a network device, wall outlet, or patch
panel. Figure shows the punch-down
connections at the back of the jack where the Ethernet UTP cable connects.
For electricity
to run between the connector and the jack, the order of the wires must follow
T568A or T568B color code found in the EIA/TIA-568-B.1 standard, as shown in
Figure . To determine the EIA/TIA category of cable that should be used to
connect a device, refer to the documentation for that device or look for a
label on the device near the jack. If there are no labels or documentation
available, use Category 5E or greater as higher categories can be used in place
of lower ones. Then determine whether to use a straight-through cable or a
crossover cable.
If the two RJ-45
connectors of a cable are held side by side in the same orientation, the
colored wires will be seen in each. If the order of the colored wires is the
same at each end, then the cable is a straight-through, as seen in Figure .
In a crossover
cable, the RJ-45 connectors on both ends show that some of the wires are
connected to different pins on each side of the cable. Figure shows that pins 1 and 2 on one connector
connect to pins 3 and 6 on the other.
Figure shows the guidelines that are used to
determine the type of cable that is required to connect Cisco devices.
Use
straight-through cables for the following connections:
- Switch to router
- Switch to PC or server
- Hub to PC or server
Use crossover
cables for the following connections:
- Switch to switch
- Switch to hub
- Hub to hub
- Router to router
- PC to PC
- Router to PC
Figure illustrates how a variety of cable types may
be required in a given network. The category of UTP cable required is based on
the type of Ethernet that is chosen.
The Lab Activity
shows the termination process for an RJ-45 jack.
The Interactive
Media Activities provide detailed views of a straight-through and crossover
cable.
The next page
explains how repeaters work.
5.1 Cabling LANs
5.1.6 Repeaters
This page will
discuss how a repeater is used on a network.
The term repeater
comes from the early days of long distance communication. A repeater was a
person on one hill who would repeat the signal that was just received from the
person on the previous hill. The process would repeat until the message arrived
at its destination. Telegraph, telephone, microwave, and optical communications
use repeaters to strengthen signals sent over long distances.
A repeater
receives a signal, regenerates it, and passes it on. It can regenerate and
retime network signals at the bit level to allow them to travel a longer
distance on the media. Ethernet and IEEE
802.3 implement a rule, known as the 5-4-3 rule, for the number of repeaters
and segments on shared access Ethernet backbones in a tree topology. The 5-4-3
rule divides the network into two types of physical segments: populated (user)
segments, and unpopulated (link) segments. User segments have users' systems
connected to them. Link segments are used to connect the network repeaters
together. The rule mandates that between any two nodes on the network, there
can only be a maximum of five segments, connected through four repeaters, or
concentrators, and only three of the five segments may contain user
connections.
The Ethernet
protocol requires that a signal sent out over the LAN reach every part of the
network within a specified length of time. The 5-4-3 rule ensures this. Each
repeater that a signal goes through adds a small amount of time to the process,
so the rule is designed to minimize transmission times of the signals. Too much
latency on the LAN increases the number of late collisions and makes the LAN
less efficient.
The next page
will discuss hubs.
5.1 Cabling
LANs
5.1.7 Hubs
This page will
describe the three types of hubs.
Hubs are actually
multiport repeaters. The difference between hubs and repeaters is usually the
number of ports that each device provides. A typical repeater usually has two
ports. A hub generally has from 4 to 24 ports.
Hubs are most commonly used in Ethernet 10BASE-T or 100BASE-T networks.
The use of a hub
changes the network from a linear bus with each device plugged directly into
the wire to a star topology. Data that arrives over the cables to a hub port is
electrically repeated on all the other ports connected to the network segment.
Hubs come in
three basic types:
- Passive
– A passive hub serves as a physical connection point only. It does not
manipulate or view the traffic that crosses it. It does not boost or clean
the signal. A passive hub is used only to share the physical media. A
passive hub does not need electrical power.
- Active –
An active hub must be plugged into an electrical outlet because it needs
power to amplify a signal before it is sent to the other ports.
- Intelligent
– Intelligent hubs are sometimes called smart hubs. They function like
active hubs with microprocessor chips and diagnostic capabilities.
Intelligent hubs are more expensive than active hubs. They are also more
useful in troubleshooting situations.
Devices attached to a hub receive all traffic that travels
through the hub. If many devices are attached to the hub, collisions are more
likely to occur. A collision occurs when two or more workstations send data
over the network wire at the same time. All data is corrupted when this occurs.
All devices that are connected to the same network segment are members of the
same collision domain.
Sometimes hubs
are called concentrators since they are central connection points for Ethernet
LANs.
The Lab Activity
will teach students about the price of different network components.
The next page
discusses wireless networks.
5.1 Cabling LANs
5.1.8 Wireless
This page will
explain how a wireless network can be created with much less cabling than other
networks.
Wireless signals
are electromagnetic waves that travel through the air. Wireless networks use
radio frequency (RF), laser, infrared (IR), satellite, or microwaves to carry
signals between computers without a permanent cable connection. The only
permanent cabling can be to the access points for the network. Workstations
within the range of the wireless network can be moved easily without the need
to connect and reconnect network cables.
A common
application of wireless data communication is for mobile use. Some examples of
mobile use include commuters, airplanes, satellites, remote space probes, space
shuttles, and space stations.
At the core of
wireless communication are devices called transmitters and receivers. The
transmitter converts source data to electromagnetic waves that are sent to the
receiver. The receiver then converts these electromagnetic waves back into data
for the destination. For two-way communication, each device requires a
transmitter and a receiver. Many networking device manufacturers build the
transmitter and receiver into a single unit called a transceiver or wireless
network card. All devices in a WLAN must
have the correct wireless network card installed.
The two most
common wireless technologies used for networking are IR and RF. IR technology
has its weaknesses. Workstations and digital devices must be in the line of
sight of the transmitter to work correctly. An infrared-based network can be
used when all the digital devices that require network connectivity are in one
room. IR networking technology can be installed quickly. However, the data
signals can be weakened or obstructed by people who walk across the room or by
moisture in the air. New IR technologies will be able to work out of sight.
RF technology
allows devices to be in different rooms or buildings. The limited range of
radio signals restricts the use of this kind of network. RF technology can be
on single or multiple frequencies. A single radio frequency is subject to
outside interference and geographic obstructions. It is also easily monitored
by others, which makes the transmissions of data insecure. Spread spectrum uses
multiple frequencies to increase the immunity to noise and to make it difficult
for outsiders to intercept data transmissions.
Two approaches
that are used to implement spread spectrum for WLAN transmissions are Frequency
Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS). The
technical details of how these technologies work are beyond the scope of this
course.
A large LAN can
be broken into smaller segments. The next page will explain how bridges are
used to accomplish this.
Web Links
5.1 Cabling LANs
5.1.9 Bridges
This page will
explain the function of bridges in a LAN.
There are times
when it is necessary to break up a large LAN into smaller and more easily
managed segments. This decreases the
amount of traffic on a single LAN and can extend the geographical area past
what a single LAN can support. The devices that are used to connect network
segments together include bridges, switches, routers, and gateways. Switches
and bridges operate at the data link layer of the OSI model. The function of
the bridge is to make intelligent decisions about whether or not to pass
signals on to the next segment of a network.
When a bridge
receives a frame on the network, the destination MAC address is looked up in
the bridge table to determine whether to filter, flood, or copy the frame onto
another segment. This decision process occurs as follows:
- If the destination device is on
the same segment as the frame, the bridge will not send the frame onto
other segments. This process is known as filtering.
- If the destination device is on
a different segment, the bridge forwards the frame to the appropriate
segment.
- If the destination address is
unknown to the bridge, the bridge forwards the frame to all segments
except the one on which it was received. This process is known as
flooding.
If placed strategically, a bridge can greatly improve
network performance.
The next page
will describe switches.
Web Links
5.1 Cabling LANs
5.1.10 Swtiches
This page will
explain the function of switches.
A switch is
sometimes described as a multiport bridge.
A typical bridge may have only two ports that link two network segments.
A switch can have multiple ports based on the number of network segments that
need to be linked. Like bridges, switches learn information about the data
frames that are received from computers on the network. Switches use this
information to build tables to determine the destination of data that is sent
between computers on the network.
Although there
are some similarities between the two, a switch is a more sophisticated device
than a bridge. A bridge determines whether the frame should be forwarded to the
other network segment based on the destination MAC address. A switch has many
ports with many network segments connected to them. A switch chooses the port
to which the destination device or workstation is connected. Ethernet switches are
popular connectivity solutions because they improve network speed, bandwidth,
and performance.
Switching is a
technology that alleviates congestion in Ethernet LANs. Switches reduce traffic
and increase bandwidth. Switches can easily replace hubs because switches work
with the cable infrastructures that are already in place. This improves
performance with minimal changes to a network.
All switching
equipment perform two basic operations. The first operation is called switching
data frames. This is the process by which a frame is received on an input
medium and then transmitted to an output medium. The second is the maintenance
of switching operations where switches build and maintain switching tables and
search for loops.
Switches operate
at much higher speeds than bridges and can support new functionality, such as
virtual LANs.
An Ethernet
switch has many benefits. One benefit is that it allows many users to
communicate at the same time through the use of virtual circuits and dedicated
network segments in a virtually collision-free environment. This maximizes the bandwidth available on the
shared medium. Another benefit is that a switched LAN environment is very cost
effective since the hardware and cables in place can be reused.
The Lab activity
will help students understand the price of a LAN switch.
The next page
will discuss NICs.
5.1 Cabling
LANs
5.1.11 Host
connectivity
This page will
explain how NICs provide network connectivity.
The function of a
NIC is to connect a host device to the network medium. A NIC is a printed
circuit board that fits into the expansion slot on the motherboard or
peripheral device of a computer. The
NIC is also referred to as a network adapter. On laptop or notebook computers a
NIC is the size of a credit card.
NICs are
considered Layer 2 devices because each NIC carries a unique code called a MAC
address. This address is used to control data communication for the host on the
network. More will be learned about the MAC address later. NICs control host access
to the medium.
In some cases the
type of connector on the NIC does not match the type of media that needs to be
connected to it. A good example is a Cisco 2500 router. This router has an AUI
connector. That AUI connector needs to connect to a UTP Category 5 Ethernet
cable. A transceiver is used to do this. A transceiver converts one type of
signal or connector to another. For example, a transceiver can connect a 15-pin
AUI interface to an RJ-45 jack. It is considered a Layer 1 device because it
only works with bits and not with any address information or higher-level
protocols.
NICs have no
standardized symbol. It is implied that, when networking devices are attached
to network media, there is a NIC or NIC-like device present. A dot on a
topology map represents either a NIC interface or port, which acts like a NIC.
The next page
discusses peer-to-peer networks.
5.1 Cabling LANs
5.1.12 Peer-to-peer
This page covers peer-to-peer networks.
When LAN and WAN
technologies are used, many computers are interconnected to provide services to
their users. To accomplish this, networked computers take on different roles or
functions in relation to each other.
Some types of applications require computers to function as equal
partners. Other types of applications distribute their work so that one
computer functions to serve a number of others in an unequal relationship.
Two computers
generally use request and response protocols to communicate with each other.
One computer issues a request for a service, and a second computer receives and
responds to that request. The requestor acts like a client and the responder
acts like a server.
In a peer-to-peer
network, networked computers act as equal partners, or peers. As peers, each
computer can take on the client function or the server function. Computer A may
request for a file from Computer B, which then sends the file to Computer A.
Computer A acts like the client and Computer B acts like the server. At a later
time, Computers A and B can reverse roles.
In a peer-to-peer
network, individual users control their own resources. The users may decide to
share certain files with other users.
The users may also require passwords before they allow others to access
their resources. Since individual users make these decisions, there is no
central point of control or administration in the network. In addition,
individual users must back up their own systems to be able to recover from data
loss in case of failures. When a computer acts as a server, the user of that
machine may experience reduced performance as the machine serves the requests
made by other systems.
Peer-to-peer
networks are relatively easy to install and operate. No additional equipment is
necessary beyond a suitable operating system installed on each computer. Since
users control their own resources, no dedicated administrators are needed.
As networks grow,
peer-to-peer relationships become increasingly difficult to coordinate. A
peer-to-peer network works well with ten or fewer computers. Since peer-to-peer
networks do not scale well, their efficiency decreases rapidly as the number of
computers on the network increases. Also, individual users control access to
the resources on their computers, which means security may be difficult to maintain.
The client/server model of networking can be used to overcome the limitations
of the peer-to-peer network.
Students will
create a simple peer-to-peer network in the Lab Activity.
The next page
discusses a client/server network.
5.1 Cabling LANs
5.1.13 Client/server
This page will
describe a client/server environment.
In a
client/server arrangement, network services are located on a dedicated computer
called a server. The server responds to the requests of clients. The server is a central computer that is
continuously available to respond to requests from clients for file, print,
application, and other services. Most network operating systems adopt the form
of a client/server relationship. Typically, desktop computers function as
clients and one or more computers with additional processing power, memory, and
specialized software function as servers.
Servers are
designed to handle requests from many clients simultaneously. Before a client
can access the server resources, the client must be identified and be
authorized to use the resource. Each client is assigned an account name and
password that is verified by an authentication service. The authentication
service guards access to the network. With the centralization of user accounts,
security, and access control, server-based networks simplify the administration
of large networks.
The concentration
of network resources such as files, printers, and applications on servers also
makes it easier to back-up and maintain the data. Resources can be located on
specialized, dedicated servers for easier access. Most client/server systems
also include ways to enhance the network with new services that extend the
usefulness of the network.
The centralized
functions in a client/server network has substantial advantages and some
disadvantages. Although a centralized server enhances security, ease of access,
and control, it 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 member to administer and maintain. Server systems also
require additional hardware and specialized software that add to the cost.
Figures and
summarize the advantages and disadvantages of peer-to-peer and client/server
networks.
In the Lab
Activities, students will build a hub-based network and a switch-based network.
This page
concludes this lesson. The next lesson will discuss cabling WANs. The first
page focuses on the WAN physical layer.
5.2 Cabling WANs
5.2.1 WAN physical layer
This page
describes the WAN physical layer.
The physical
layer implementations vary based on the distance of the equipment from each
service, the speed, and the type of service.
Serial connections are used to support WAN services such as dedicated
leased lines that run PPP or Frame Relay. The speed of these connections ranges
from 2400 bps to T1 service at 1.544 Mbps and E1 service at 2.048 Mbps.
ISDN offers
dial-on-demand connections or dial backup services. An ISDN Basic Rate
Interface (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 is typically used to carry data over the B channels.
As the demand for
residential broadband high-speed services has increased, DSL and cable modem
connections have become more popular. Typical residential DSL service can
achieve T1/E1 speeds over the telephone line. Cable services use the coaxial
cable TV line. A coaxial cable line provides high-speed connectivity that
matches or exceeds DSL. DSL and cable modem service will be covered in more
detail in a later module.
Students can
identify the WAN physical layer components in the Interactive Media Activity.
The next page
will describe WAN serial connections.
5.2 Cabling WANs
5.2.2 WAN serial connections
This page will
discuss WAN serial connections.
For long distance
communication, WANs use serial transmission. This is a process by which bits of
data are sent over a single channel. This process provides reliable long
distance communication and the use of a specific electromagnetic or optical
frequency range.
Frequencies are
measured in terms of cycles per second and expressed in Hz. Signals transmitted
over voice grade telephone lines use 4 kHz. The size of the frequency range is
referred to as bandwidth. In networking, bandwidth is a measure of the bits per
second that are transmitted.
For a Cisco
router, physical connectivity at the customer site is provided by one of two
types of serial connections. The first type is a 60-pin connector. The second
is a more compact ‘smart serial’ connector. The provider connector will vary
depending on the type of service equipment.
If the connection
is made directly to a service provider, or a device that provides signal
clocking such as a channel/data service unit (CSU/DSU), the router will be a
data terminal equipment (DTE) and use a DTE serial cable. Typically this is the
case. However, there are occasions where the local router is required to
provide the clocking rate and therefore will use a data communications
equipment (DCE) cable. In the curriculum router labs one of the connected
routers will need to provide the clocking function. Therefore, the connection
will consist of a DCE and a DTE cable.
The next page
will discuss routers and serial connections.
5.2 Cabling WANs
5.2.3 Routers and serial connections
This page will
describe how routers and serial connections are used in a WAN.
Routers are
responsible for routing data packets from source to destination within the LAN,
and for providing connectivity to the WAN. Within a LAN environment the router
contains broadcasts, provides local address resolution services, such as ARP
and RARP, and may segment the network using a subnetwork structure. In order to
provide these services the router must be connected to the LAN and WAN.
In addition to
determining the cable type, it is necessary to determine whether DTE or DCE
connectors are required. The DTE is the endpoint of the user’s device on the
WAN link. The DCE is typically the point where responsibility for delivering
data passes into the hands of the service provider.
When connecting
directly to a service provider, or to a device such as a CSU/DSU that will
perform signal clocking, the router is a DTE and needs a DTE serial cable. This is typically the case for routers.
However, there are cases when the router will need to be the DCE. When
performing a back-to-back router scenario in a test environment, one of the
routers will be a DTE and the other will be a DCE.
When cabling
routers for serial connectivity, the routers will either have fixed or modular
ports. The type of port being used will affect the syntax used later to
configure each interface.
Interfaces on
routers with fixed serial ports are labeled for port type and port number.
Interfaces on
routers with modular serial ports are labeled for port type, slot, and port
number. The slot is the location of the
module. To configure a port on a modular card, it is necessary to specify the
interface using the syntax “port type slot number/port number”. Use the label
“serial 1/0”, when the interface is serial, the slot number where the module is
installed is slot 1, and the port that is being referenced is port 0.
The first Lab
Activity will require students to identify the Ethernet or Fast Ethernet
interfaces on a router.
In the next two
Lab Activities, students will create and troubleshoot a basic WAN.
The next page
discusses routers and ISDN BRI connections.
5.2 Cabling WANs
5.2.4 Routers and ISDN BRI connections
This page will
help students understand ISDN BRI connections.
With ISDN BRI,
two types of interfaces may be used, BRI S/T and BRI U. Determine who is
providing the Network Termination 1 (NT1) device in order to determine which
interface type is needed.
An NT1 is an
intermediate device located between the router and the service provider ISDN
switch. The NT1 is used to connect four-wire subscriber wiring to the
conventional two-wire local loop. In North America, the customer typically
provides the NT1, while in the rest of the world the service provider provides
the NT1 device.
It may be
necessary to provide an external NT1 if the device is not already integrated
into the router. Reviewing the labeling on the router interfaces is usually the
easiest way to determine if the router has an integrated NT1. A BRI interface
with an integrated NT1 is labeled BRI U. A BRI interface without an integrated
NT1 is labeled BRI S/T. Because routers can have multiple ISDN interface types,
determine which interface is needed when the router is purchased. The type of
BRI interface may be determined by looking at the port label. To interconnect the ISDN BRI port to the
service-provider device, use a UTP Category 5 straight-through cable.
CAUTION:
It is important
to insert the 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.
5.2 Cabling WANs
5.2.5 Routers and DSL connections
This page
describes routers and DSL connections.
The Cisco 827
ADSL router has one asymmetric digital subscriber line (ADSL) interface. To connect an ADSL line to the ADSL port on a
router, do the following:
- Connect the phone cable to the
ADSL port on the router.
- Connect the other end of the
phone cable to the phone jack.
To connect a
router for DSL service, use a phone cable with RJ-11 connectors. DSL works over
standard telephone lines using pins 3 and 4 on a standard RJ-11 connector.
The next page
will discuss cable connections.
Web Links
5.2 Cabling WANs
5.2.6 Routers and cable connections
This page will explain how routers are connected to cable
systems.
The Cisco uBR905
cable access router provides high-speed network access on the cable television
system to residential and small office, home office (SOHO) subscribers. The
uBR905 router has a coaxial cable, or F-connector, interface that connects directly
to the cable system. Coaxial cable and an F connector are used to connect the
router and cable system.
Use the following
steps to connect the Cisco uBR905 cable access router to the cable system:
- Verify that the router is not
connected to power.
- Locate the RF coaxial cable
coming from the coaxial cable (TV) wall outlet.
- Install a cable
splitter/directional coupler, if needed, to separate signals for TV and
computer use. If necessary, also install a high-pass filter to prevent
interference between the TV and computer signals.
- Connect the coaxial cable to
the F connector of the router.
Hand-tighten the connector, making sure that it is finger-tight,
and then give it a 1/6 turn with a wrench.
- Make sure that all other
coaxial cable connectors, all intermediate splitters, couplers, or ground
blocks, are securely tightened from the distribution tap to the Cisco
uBR905 router.
CAUTION:
Do not over
tighten the connector. Over tightening may break off the connector. Do not use
a torque wrench because of the danger of tightening the connector more than the
recommended 1/6 turns after it is finger-tight.
The next page
will discuss console connections.
5.2 Cabling WANs
5.2.7 Setting up console connections
This page will explain how console connections are set up.
To initially
configure the Cisco device, a management connection must be directly connected
to the device. For Cisco equipment this management attachment is called a
console port. The console port allows monitoring and configuration of a Cisco
hub, switch, or router.
The cable used
between a terminal and a console port is a rollover cable, with RJ-45
connectors. The rollover cable, also known as a console cable, has a different
pinout than the straight-through or crossover RJ-45 cables used with Ethernet
or the ISDN BRI. The pinout for a rollover is as follows:
1 to 8
2 to 7
3 to 6
4 to 5
5 to 4
6 to 3
7 to 2
8 to 1
To set up a
connection between the terminal and the Cisco console port, perform two steps.
First, connect the devices using a rollover cable from the router console port
to the workstation serial port. An RJ-45-to-DB-9 or an RJ-45-to-DB-25 adapter
may be required for the PC or terminal.
Next, configure the terminal emulation application with the following
common equipment (COM) port settings: 9600 bps, 8 data bits, no parity, 1 stop
bit, and no flow control.
The AUX port is
used to provide out-of-band management through a modem. The AUX port must be
configured by way of the console port before it can be used. The AUX port also
uses the settings of 9600 bps, 8 data bits, no parity, 1 stop bit, and no flow
control.
In the Lab
Activity, students will establish a console connection to a router or switch.
The Interactive
Media Activity provides a detailed view of a console cable.
This page
concludes this lesson. The next page will summarize the main points from the
module.
Summary
This page
summarizes the topics discussed in this module.
Ethernet is the most widely used LAN technology and can be
implemented on a variety of media. Ethernet technologies provide a variety of
network speeds, from 10 Mbps to Gigabit Ethernet, which can be applied to
appropriate areas of a network. Media and connector requirements differ for
various Ethernet implementations.
The connector on
a network interface card (NIC) must match the media. A bayonet nut connector
(BNC) connector is required to connect to coaxial cable. A fiber connector is
required to connect to fiber media. The registered jack (RJ-45) connector used
with twisted-pair wire is the most common type of connector used in LAN
implementations. Ethernet
When twisted-pair
wire is used to connect devices, the appropriate wire sequence, or pinout, must
be determined as well. A crossover cable is used to connect two similar
devices, such as two PCs. A straight-through cable is used to connect different
devices, such as connections between a switch and a PC. A rollover cable is
used to connect a PC to the console port of a router.
Repeaters
regenerate and retime network signals and allow them to travel a longer
distance on the media. Hubs are multi-port repeaters. Data arriving at a hub
port is electrically repeated on all the other ports connected to the same
network segment, except for the port on which the data arrived. Sometimes hubs
are called concentrators, because hubs often serve as a central connection
point for an Ethernet LAN.
A wireless
network can be created with much less cabling than other networks. The only
permanent cabling might be to the access points for the network. At the core of
wireless communication are devices called transmitters and receivers. The
transmitter converts source data to electromagnetic (EM) waves that are passed
to the receiver. The receiver then converts these electromagnetic waves back
into data for the destination. The two most common wireless technologies used
for networking are infrared (IR) and radio frequency (RF).
There are times
when it is necessary to break up a large LAN into smaller, more easily managed
segments. The devices that are used to define and connect network segments
include bridges, switches, routers, and gateways.
A bridge uses the
destination MAC address to determine whether to filter, flood, or copy the
frame onto another segment. If placed strategically, a bridge can greatly
improve network performance.
A switch is
sometimes described as a multi-port bridge. Although there are some
similarities between the two, a switch is a more sophisticated device than a
bridge. Switches operate at much higher speeds than bridges and can support new
functionality, such as virtual LANs.
Routers are
responsible for routing data packets from source to destination within the LAN,
and for providing connectivity to the WAN. Within a LAN environment the router
controls broadcasts, provides local address resolution services, such as ARP
and RARP, and may segment the network using a subnetwork structure.
Computers
typically communicate with each other by using request/response protocols. One
computer issues a request for a service, and a second computer receives and
responds to that request. In a peer-to-peer network, networked computers act as
equal partners, or peers. As peers, each computer can take on the client
function or the server function. In a client/server arrangement, network
services are located on a dedicated computer called a server. The server
responds to the requests of clients.
WAN connection
types include high-speed serial links, ISDN, DSL, and cable modems. Each of
these requires a specific media and connector. To interconnect the ISDN BRI
port to the service-provider device, a UTP Category 5 straight-through cable
with RJ-45 connectors, is used. A phone cable and an RJ-11 connector are used
to connect a router for DSL service. Coaxial cable and a BNC connector are used
to connect a router for cable service.
In addition to
the connection type, it is necessary to determine whether DTE or DCE connectors
are required on internetworking devices. The DTE is the endpoint of the user’s
private network on the WAN link. The DCE is typically the point where
responsibility for delivering data passes to the service provider. When
connecting directly to a service provider, or to a device such as a CSU/DSU
that will perform signal clocking, the router is a DTE and needs a DTE serial
cable. This is typically the case for routers. However, there are cases when
the router will need to be the DCE.
No comments:
Post a Comment