Computer networks cabling LANs & WANs

Computer networks cabling LANs & WANs, mạng máy tính, cáp mạng

UTP implementation Repeaters

Hubs Wireless Bridges switches Host connectivity Peer-to-peer

Client/server

5.2 Cabling the WAN WAN physical layer

WAN serial connections

Routers and serial

connections Routers and ISDN BRI

connections Routers and DSL connections

Routers and cable

connections Setting up console connections

5.1 Cabling the LAN

7/19/2008

LAN physical layer

Various symbols are used to

ing /

represent media types B”

Each media has advantages and

disadvantages

Cable length Cost

Ethernet in the campus

Ethernet is the most widely used LAN technology

IEEE 802.3 specification is released in 1980

IEEE extended 802.3 to three new committees 802.3u (Fast Ethernet)

802.3z (Gigabit Ethernet over Fiber) 802.3ab (Gigabit Ethernet over UTP) The new generation applications can easily overwhelm a network bandwidth (10M/100M)

Conceder providing GE from the backbone to the end user ?

GE to the desktop is not a standard installation now

Ethernet technologies in campus network User level (10Mbps) / Clients or servers (100Mbps) link between user and network devices

Fast Ethernet can be used to connect enterprise servers

Fast Ethernet or Gigabit Ethernet, as affordable, should be implemented between backbone devices

7/19/2008

Ethernet in the campus (cont )

Ethernet Fast Ethernet Gigabit Ethernet

10BASE-T Implementation Implementation implementation

End-user Level | Provides connectivity for) Gives high- Not typically used at (End-user device | low-to medium-volume | performance PC this level

to workgroup applications workstations 100- device) Mbps access to the

server

Workgroup Not typically Provides connectivity | Provides high-

Level used at this level between the end user | performance (Workgroup and workgroups connectivity to the device to Provides connectivity | enterprise server block

backbone) from the workgroup to

backbone Provides

connectivity from the server block to the backbone layer

Backbone Level | Not typically Provides connectivity | Provides high-speed

used at this from the workgroup | backbone and network level server block to the device connectivity

backbone

Ethernet media and connector

Media 50-ohm 50-ohm EIA/TIA EIA/TIA 62.5/125 STP EIA/TIA 62.5/50 62.5/50 micro

coaxial coaxial Category Category 5 multimode Category 5 micro multimode (Thinnet) (Thicknet ' 3,4, 5 UTP, two fiber UTP, four multimode fiber; 9-micron

UTP, two pair pair fiber single-mode

Maximum 185m 500 m 100 m (328 100 m (328 feet) 400m (1312.3 | 25m (82 feet) 100 m (328 feet) | 275 m (853 feet) | 440 m (1443.6 feet) Segment (606.94 (1640.4 feet) feet) for 62.5 micro for 62.5 micro fiber; Length feet) feet) fiber; 550 m 550 m (1804.5 feet)

(1804.5 feet) for | for 50 micro fiber; 3 to

50 micro fiber 10 km (1.86 to 6.2

miles) on single-mode fiber

Connector BNC Attachment | ISO 8877 ISO 8877 Duplex media ISO 8877 ISO 8877 SC connector SC connector

unit (RJ-45) (RJ-45) interface (RJ-45) (RJ-45) interface connector (MIC)

(AUI) ST or SC

connector

Connection media

A transceiver is an adapter that converts one type of connection to another

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

Four of the wires carry the voltage and are considered “tio” (T1 through 14)

The other four wires are grounded and are called “ring” (R1 through R4)

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, and so on

Use siraight-through cables for the following cabling:

Switch to router Switch to PC or server Hub to PC or server

Use crossover cables for the following cabling:

Switch to switch Switch to hub Hub to hub

Router to router

PC to PC Router to PC

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UTP implementation (cont }

UTP implementation (cont

3 RD+ ‘OFege ogeqe 4 NC 4 NC afade :Í: |:

5 NC wowaw ow wb wowbwgwb 6 TD+ 6 TD- r r

o gli b b r o gli b b r 7 NC 7 NC The orange wire pair and the green wire

6 RD- Wi bị d 8 NC 8 NC pair switch places on one end of the cable

res on cable ends

7 NC

8 NC are in same order

1000-Mbps Category 5 : LP

UTP implementation (cont }

Lab 5.1.5 RJ-45 Jack Punch Down The process of punching down wires into a data jack in an office area is the same as punching them down in a patch panel in a wiring closet

The following resources are required:

60 - 90 cm (2 - 3 feet) length of Category 5/5e cabling, which can be one per person or one per team

Two Category 5/5e RJ-45 data jacks (one extra for spare) — If RJ-45 data jacks are installed on both ends of the cable, the installation can

be tested by inserting cable with RJ-45 connectors and a simple cable continuity tester

Category 5/5e wall plate

110 type punch-down tool Wire cutters

single Wire punch tool

Repeaters

The purpose of a repeater is to regenerate and retime network signals

at the bit level This allos them to travel a longer distance on the media

No more than four repeaters can be used between hosts on a LAN

To limit latency added to frame travel by each repeater

Too much latency on the LAN increases the number of late collisions and makes the LAN less efficient

Hubs

Hubs are actually multiport repeaters

Star topology With hubs, data arriving over the cables to 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 was sent (broadcast) Hubs come in three basic types:

Passive hub

lt serves as a physical connection point only

It is used only to share the physical media

It does not need electrical power

Active hub

Electrical power id needed

It amplify the incoming signal before passing it out to the other ports

Hubs (cont )

pevices attached to a hub receive all traffic traveling through the

ub

more devices > more collisions

A collision occurs when two or more workstations send data over the network wire at the same time All data is corrupted when that occurs

Every device connected to the same network segment is said to

be a member of a collision domain

Sometimes hubs are called concentrators, because hubs serve as a central connection

point for an Ethernet LAN

Wireless

Wireless data communication

for mobile applications or users ex: commuters, airplanes, satellites, remote Space probes, space shuttles, and space

stations

IR(I nfra Red) Access points (transceivers)

All devices must be in the line of sight of the transmitter in order to operate mm + New IR technologies being developed that 2

can work out of sight Workstation

obstructions The limited range of radio signals restricts the use of this kind of network

RF technology can be on single or multiple Bindi dower frequencies

Frequency Hopping Spread Spectrum (FHSS)

/ Direct Sequence Spread Spectrum (DSSS)

This decision process occurs as follows:

lf the destination device is on the same segment as the frame, the

bridge blocks the frame from going on to 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

lf 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

lf placed strategically, a bridge can greatly improve network performance

Switches

A switch is sometimes described as a multiport bridge

In data communications today, all switching equipment performs two basic operations

The first operation is called switching data frames

The second is the maintenance of switching operations where switches build and maintain switching tables and search for loops

lt supports new functionality, such as virtual LANs

An Ethernet switch has many benefits

One benefit is that an Ethernet switch allows many users to communicate in parallel 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 moving to a switched LAN environment is very

cost effective because existing hardware and cabling can be reused

Host connectivity

The function of a NIC Is to connect a host device to

the network medium

NICs are considered Layer 2 devices

It has a unique MAC address on it

When the type of connector on the NIC does not match the type of media, a transceiver is needed

A transceiver converts one type of signal or connector to another It is considered a Layer 1 device because it only works with bits, and not with any address information or higher-level protocols

Peer-to-peer

In a peer-to-peer network, networked computers act

as equal partners, or peers

Each computer can take on the client function or the server function

In a peer-to-peer network, individual users control their own resources

Peer-to-peer networks are relatively easy to install and operate

A peer-to-peer network works well with 10 or fewer

computers

The security may be difficult to maintain

Client/server

servers are designed to handle requests from many clients simultaneously and continuously available to respond to requests from clients (ex: file, print,

application, and other services) Typically, desktop computers function as clients, one

or more computers with additional processing power, memory, and specialized software function as

servers

The client must be identified and be authorized to use

the server resource (ex: account name and

password for resources)

With the centralization of user accounts, security, and

access control, server-based networks simplify the administration of large networks

_ Less expensive to implement _ Provides for better security

- Does not require additional specialized Easier to administer when the network is large

network administration software because administration is centralized

Does not require a dedicated network arivinictrstor All data can be backed up on one central location

Requires expensive specialized network

administrative and operational software

‘Requires expensive, more powerful hardware for the server machine

Has a single point of failure User data is

unavailable if the server is down

5.2 Cabling the WAN

WAN physical layer

The physical layer implementations vary depending on the distance of the equipment from the services, the speed, and the type of service itself

serial connections are used to support WAN services such as ceaicated leased lines that run Point-to-Point Protocol (PPP) or Frame elay

T1 service at 1.544 Mbps 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

Broadband high-speed services DSL service can achieve T1/E1 speeds over the existing telephone line Cable services use the existing coaxial cable TV line A coaxial cable

rg Provides high-speed connectivity matching or exceeding that of

WAN physical layer (cont )

* Physical Layer implementation vary

* Cable specifications define speed of link

WAN serial connections

‘Smart serial’ connector

The provider connector will vary depending on the type of

service equipment

lf 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 DIE Serial cable

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, the connection will consist of a DCE and aDTIE cable

WAN serial connections (cont.)

T1 (1.544 Mbps) — 15

32

WAN serial connections (cont.)

End-User Router Connections

Routers and serial connections

Routers are responsible for routing data packets trom

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

To configure a port on a modular card, it is necessary

to specify the interface using the syntax “port type slot number/port number.” (ex: “serial 1/0,” slot 1/ port

0)

Routers and serial connections (cont.)

Data Terminal Equipment: Data Communications Equipment:

- End of the user's device - End of the WAN provider's

on the WAN Link side of the communication facility

- Responsible for clocking

Cisco 2503 Router-Rear View

Ethernet Synchronous System

AUI LED Serial LEDs OK LED

|

=———<—= ae _—— —— —— —— _-ô Co Colo oe ae) coc KT @

AUl—¬1 SERIAL 0 ` SERIAL ` BRI = | CONSOLE AUX 4 i

Gee)? O Ce)? Ce)? 9 [ROG] [Ra] 0 fof Of

Pot pra On/off Power

Ethernet Synchronous BRI Aux switch

AUI port serial ports port port

(DB-15) (DB-60) Console

port