Components of a LAN Network

8/13/2019 Components of a LAN Network

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Components of a LAN Network :-

The components used to establish a local area network (LAN) have a variety of functions. The common unifying theme

among them is that they facilitate communication between two or more computers. LAN components are

configurable in a variety of ways, but a LAN always requires the same basic components.

Network Cards - At the most basic level, a network card is a component that allows the computer to communicateacross a network. This component is frequently built into the motherboard of today's computers, but it can also be

a separate card for use in a PCI slot, or part of an external unit that connects to the computer via a USB port.

Network cards are further categorized according to whether they operate on wired or wireless networks.

However, some cards do support both wireless and wired networking.

Network Cables - Network cables are the physical lines used to carry information between computers in a wiredLAN. The cables are labeled by their category and are commonly referred to as CatX--where X is the category

number--cable. The most commonly used type in 2010 is Cat5, although other categories with different properties

do exist.

Network Hubs - A network hub acts as a centralized point for data transmission to computers in a LAN. When datafrom one computer reaches the hub it is broadcast to every computer in the network regardless of where the data

is intended to go. Network bandwidth on LANs using a network hub is shared, which means that four computers

on a hub will each get one-quarter the total bandwidth available on the hub.

Network Switches - An alternative to the network hub is the network switch. Switches represent a newernetworking technology that assigns each computer in the network a specific MAC address. This allows LANs using

a network switch to route information to individual computers. Because network switches do not broadcast to

every computer on the network, they can simultaneously allot their full bandwidth to each computer.

Routers - Unlike switches and hubs, network routers are used to connect networks to one another, rather thanconnecting computers in a single network. Routers can connect groups of computers that are separated by a wall

or by an ocean. They are most commonly found in the home, where they facilitate the connection of home

computers to the Internet; however, they can be used to connect networks of any kind. Most modern network

routers are actually combination units that contain a router and a network switch, in addition to a handful of other

networking-related tools such as a DHCP server and a firewall.

LAN Network Requirements :-

Creating a local area network is becoming more common in homes and small businesses. The basic requirements for a

LAN are inexpensive hardware components and some software configurations on the computers. A home network is

used to combine one or several machines. The network may even extend to wireless, where laptops are used to

connect. However, to start the LAN setup, there are only some basic requirements.

Router or Hub - The router or hub are two types of hardware components in which the traffic is merged andcomputers are connected. A hub is just a central device, and the data is not filtered. Data is broadcast with no

controls. However, a router is a more intelligent machine that routes data packets and sends them to the right

section of the network. Routers can also be used as firewall protection from the Internet. Because routers have

become relatively inexpensive, they are preferred over hubs.

Connection Method - The two most popular connection methods are hard wiring using ethernet cables or usingwireless technologies. Most desktop networks use ethernet cables. These are inexpensive products that directly

connect the network card of the computer to the router. Wireless technologies are used most often for laptops.

However, to use a wireless network, the administrator needs to set up a wireless router.

Network Cards - Network cards are hardware components added to machines that allow them to communicate.Network cards are used in any type of network. Wireless network cards are usually installed with any laptop

purchase. However, hard wire network cards are also available for these machines. Network cards are inserted

into a slot on a desktop that connects to the computer's motherboard. These are connected to the rest of the

network using Ethernet cables that attach to the back of the card.


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Operating System Setup - The hardest part of a network design is setting up the software and operating system.The operating system needs to recognize the network card in the machine. It needs to have a protocol configured.

The typical protocol on a network is TCP/IP. TCP/IP creates a unique address for the machine. The operating

system retrieves an IP address from a server, or it can be defined in the network settings.

Security - Security is a major concern for any network administrator. The administrator of a small home networkdoes not need to implement much security on the network. Most home networks are peer-to-peer, allowing users

to share files without permissions. Larger networks require security. This is done by creating a domain and forcing

users to login to a server before accessing networking resources.

LAN Wiring & Pin outs :-

Crossed and Straight cables - when to use them :-

The following diagram shows the Normaluse of Crossed and Straight cables (see also the notes below).

Standards Summary

The various standards can get a tad complicated and messy. We get occasional email requesting a summary

of the standards - this is our attempt to provide a quick overview.

Standard Required Pairs 10M 100M 1000M Notes

10base-T 2 (1/2 and 3/6) yes yes no 100m support only if no cat 3/4 in run

100base-TX 2 (1/2 and 3/6) yes yes no 100m support only if no cat 3/4 in run

100base-T4 4 (1/2, 3/6, 4/5 and 7/8) yes yes yes

1000base-T 4 (1/2, 3/6, 4/5 and 7/8) yes yes yes Functionally identical to 100base-T4


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10baseT Straight Cable (PC to HUB/SWITCH) :-

Straight cables are used to connect PCs or other equipment to a HUB or Switch. If your connection is PC toPC or HUB to HUB you MUST use aCrossed cable.

The following cable description is for the wiring of both ends (RJ45 Male connectors) with the 568B category

5(e)wiring colorsyou could, of course, use the 568A colour scheme.

Pin No. strand color Name

1 white and orange TX+

2 orange TX-

3 white and green RX+

4 NC *

5 NC *

6 green RX-

7 NC *

8 NC *NOTE:Items marked * are not necessary for 10M LANs (10base-T) but since you will be moving shortly to

100MB LANs (won't you) you will save yourself a LOT OF TIMEfinding crappy cable (that you made) that

does not work. Instead we suggest you wire to100Base-T4 standards.After all you gotta stick the endssomewhere man.

We use BLUEfor 10base-T straight cables. NOTE: All our wiring is now done to the 100base-T4 spec whichyou can use with 10base-T networks - but NOT necessarily the other way around.

10baseT Crossed cable (PC to PC or HUB to HUB) :-

Crossed cables are used to connect PCs to one other PC or to connect a HUB to a HUB. Crossed cables aresometimes called Crossover, Patch or Jumper cables. If your connection is PC to HUB you MUST use a

Straight cable.

The following description shows the wiring at both ends (male RJ45 connectors) of the crossed cable.

One end

RJ45 Male

Other end

RJ45 Male

1 3

2 6

3 1

4 * 5 *

5 * 4 *

6 2

7 * 8 *

8 * 7 *
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NOTES:

1. Items marked * are not necessary for 10M LANs but since you will be moving shortly to 100MB LANs (won'tyou) you will save yourself a LOT OF TIMEfinding crappy cable (that you made) that does not work. Instead we

suggest you wire to100BaseT standards.

2. We use REDfor crossed cables (or more commonly now a red heat-shrink collar at each end).3. All our crossed wiring is done to the 100base-T4 spec which you can use with 10baseT networks - but NOT

always the other way around.

100base-T Straight Cable (PC to HUB/SWITCH) :-

Straight cables are used to connect PCs or other equipment to a HUB or Switch. If your connection is PC to

PC or HUB to HUB you MUST use aCrossed cable.The following cable description is for the wiring of BOTH ends (RJ45 Male connectors) with yourcategory 5

wiring colors(TIA/EIA 568A or 568B though the example uses 568B colors).

Pin No. conductor color Name

1 white and orange TX_D1+

2 orange TX_D1-

3 white and green RX_D2+

4 blue BI_D3+ **

5 white and blue BI_D3- **

6 green RX_D2-

7 white and brown BI_D4+ **

8 brown BI_D4- **

We use BLUEfor 100baseT straight cables.

NOTES:

1. Wires marked ** are ABSOLUTELY NECESSARY for 100Base-T4 networks - used when anycombination of category 3/4/5 cables are present, when using 1000base-T (GigE) and MAY be

required for Power-over-Ethernet (PoE) - see below.

2. Wires marked ** are not essential for 100Base-TX (using cat 5/5e ONLY cables) and CAN be usedfor other purposes, for example, telephony but,.. beware.. read this FAQand ourLAN plus

Telephony articlebefore you wire your entire neighbourhood for surround sound.

3. The Power-over-Ethernet spec (802.3af) allows three schemes where power may be supplied. Two ofthese schemes use pairs 4,5 and 7,8 (marked ** in above table) for power (called Midspan PSE andAlternative B or Mode B), one scheme uses ONLY pairs 1,2 and 3,6 (Endpoint PSE, Alternative A or

Mode A) for both signals and power. Depending on which scheme you use pairs 4,5 and 7,8 may be

required.4. Gigabit Ethernet requires all 4 pairs (8 conductors).5. All our wiring is now done to the 100base-T4 spec which you can use with 10baseT networks - but

NOT the other way around.
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100base-T Crossed cable (PC to PC or HUB to HUB) :-

Crossed cables are used to connect PCs to one other PC or to connect a HUB to a HUB. Crossed cable are

sometimes called Crossover, Patch or Jumper cables. If your connection is PC to HUB you MUST use a

Straight cable.

The following description shows the wiring at both ends (male RJ45 connectors) of the crossed cable. Note:

The diagrams below shows crossing of all 4 pairs and allows for the use of cat3/4 cables with 100m LANs

(100base-T4). Pairs 4,5 and 7,8 do not NEED to be crossed in 100base-TX wiring. See notes below.

We use REDfor crossed cables (or more commonly now a red heat-shrink collar at each end).

NOTES:

1. All our crossed wiring is now done to the 100base-T4 spec (uses all 4 pairs, 8 conductors) which you can usewith 10base-T networks - but NOT necessarily the other way around.

2. Many commercial 100m LAN cables seem not to cross pairs 4,5 and 7,8. If there is no cat3/4 wiring in thenetwork this perfectly acceptable.

3. Gigabit Ethernet uses all 4 pairs so requires the full 4 pair (8 conductor) cross configuration (shown above).4. If you are using Power-over-Ethernet (802.3af) then Mode A or Alternative A uses pairs 1,2 and 3,6 for both

signals and power. Mode B or alternative B uses 4,5 and 7,8 to carry power. In all cases the spec calls for

polarity insensitive implementation (using a diode bridge) and therefore crossing or not crossing pairs 4,5 and

7,8 will have no effect.
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1000base-T Gigabit Ethernet :-

1000base-T is the copper based version of the gigabit Ethernet standard defined by 802.3ab which, since it is

over 6 months old, is available free of charge from the enlightened IEEE. Great work. In passing, if you want

to see sophistry raised to an art form read the EIA's justification for charging for their specifications. (Note:

The original EIA statement is unfortunately no longer avilable on-line. This is a great loss to both the

development of the English language in general, and comedy writing in particular.) The following notes applyto the 1000base-T spec:

1. The standard defines auto-negotiation of speed between 10, 100 and 1000 Mbit/s so the speed will fallto the maximum supported by both ends - ensuring inter-working with existing installations.

2. The cable specification base-line is ANSI/TIA/EIA-568-A-1995 (which you have to pay for). Thismeans that if you knowyour cat5 cable was manufactured to this standard (there was a lower spec

1991 version of this specification) then it will support Gigabit Ethernet. Cat5 cable manufactured to

the old specification may work or it may not - you need to run some tests. Cat5e and cat6 being higher

spec cables will clearly support Gigabit Ethernet.3. Maximum runs are the standard 100m (~300ft).4. Gigabit Ethernet uses all 4 pairs (8 conductors). The transmission scheme is radically different (PAM-

5 a 5 level amplitude modulation scheme) and each conductor is used for send and receive.5. Crossed Gigabit Ethernet cables mustcross all 4 pairs.

Shielded Twisted Pair :-

Shielded Twisted Pair (STP) comes in a variety of formats. It is typically used in three applications:

1. Where there is significant EMI (Electro-Magnetic Induction) in the environment such as caused byhigh-powered electric motors (such as in elevator shafts), flourescent lighting etc. Additionally where

there is significant Alien Crosstalk (ANEXT) such as in very high speed (gigabit and 10gb) LANs. In

this case the ethernet signals in the cable require protection against external interference from eitheradjacent pairs or the environment.

2. Where there is extremely sensitive electrical/electronic equipment in the surrounding environment orwhere security requirements demand elimination of eavesdropping possibilities from radiated LAN

signals (TEMPEST). In this case the ethernet signals in the shielded cable are contained and preventedfrom polluting, or escaping into, the external environment.

3. Where maximum performance - either speed or distance - is required. As Ethernet speeds continue toincrease either fiber or Shielded Twisted Pair is becoming increasingly common, for instance, to reach100m distances at 10Gb speeds on copper will require shielded cable (limited to 55m for UTP).

Shielded cable comes in three broad types with a confusing range of terminology:1. Where there is a single foil (FTP - Foil Twisted Pair) or braided (ScTP - Screened Twisted Pair) shield

inside the jacket covering all four pairs. Suitable for applications 1 and 2 above.2. Where there is a foil shield covering each pair. This is frequently refered to as PiMF (Pairs in Metal

Foil) and is designed primarily to eliminate Alien Cross-talk (ANEXT) from adjacent pairs. Suitablefor application 3 above.

3. Where there is a foil shield covering each pair and a (Foil or Braided) shield covering the whole cable.This is frequently refered to as SSTP (Double Shield Twisted Pair) or even PiMF - since manymanufacturers also add a jacket shield to foil covered pair cables. Suitable for applications 1, 2 and 3

above.
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In almost all cases there is a single ground wire (called a drain) which allows for connection to secondary

grounding sources.

The diagram below illustrates the differences:

Notes:

1. Shielded cable of any variety has a greater diameter than UTP and will therefore occupy more space incable ducting and raceways.

2. Connecting shielded cable is more complex and time consuming - but not execessively so - thanconventional UTP. Manufacturers specifications vary enormously, expecially with respect togrounding, and should be followed closely.

3. In shielded cable installations the jacks and receptacles are typically made of metal and the cableshield (foil or braid) is connected electrically to the connector and thence through the metal receptableto a suitable ground provided by the end equipment.

4. Foil covered pairs are typically not connected to ground and thus provide only alien crosstalkimmunity from adjacent pairs (ANEXT).

5. Manufacturers specifications and measurements suggest that shielded cables do NOT create antennaeffects - indeed experiments show that UTP creates a substantially greater antenna effect (~40db) over

correctly grounded shielded cables.

6. Even ungrounded shielded cables provide better performance (by ~20db) than conventional unshieldedtwisted pair (UTP).

7. The drain wire provides a secondary or auxiliary ground method in cases where metallic pathgrounding is provided by the connectors and, as such, is optional. In cases where metal connectors are

not being used (there is no grounding via the connectors) the drain wire may be used as the primarygrounding method and needs to be routed independantly to a suitable ground. The drain wire (cable

ground) needs to be exposed before connector. This process could require a considerable length of

exposed drain wire depending on the location of the ground source. A plastic insulating sheath shouldbe placed over the drain wire to minimize electrical hazards.

8. In all cases where both ends of a shielded cable are gounded this should be done using a common(building) ground to avoid ground potential loops which if they exceed 1V will have serious effects on

cable performance. It is also important to note that 'grounding both ends' means final equipmentterminations. Intermediate jacks or faceplates must maintain electrical continuity throughout the cable

run but are not themselves grounded.This app note from AMPprovides a detailed explanation.
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Components of a LAN Network