Category 5 cable
From Wikipedia, the free encyclopedia
Category 5 cable is a twisted pair high signal integrity cable type often referred to as Cat5 or Cat-5. Most
Category-5 cables are unshielded, relying on the twisted pair design for noise rejection. Category 5 has been
superseded by the Category 5e specification. This type of cable is used in structured cabling for computer
networks such as Ethernet and ATM, and is also used to carry many other signals such as telephony and video.
8P8C modular plug pin positioning
TIA/EIA-568-A.1-2001 T568A Wiring
Pin Pair Wire
Color
1 3
1
white/green
2
3
2
green
3
2
1
white/orange
4
1
2
blue
5
1
1
white/blue
6
2
2
orange
7
4
1
white/brown
8
4
2
brown
TIA/EIA-568-B.1-2001 T568B Wiring[1]
Pin Pair Wire
Color
1
2
1
white/orange
2
2
2
orange
3
3
1
white/green
4
1
2
blue
5
1
1
white/blue
6
3
2
green
7
4
1
white/brown
8
4
2
brown
USOC/RJ61 Wiring
Pin Pair Wire
Color
1 4
tip
white/brown
2
3
tip
white/green
3
2
tip
white/orange
4
1
ring
blue
5
1
tip
white/blue
6
2
ring
orange
7
3
ring
green
8
4
ring
brown
Partially stripped cable showing the twisted pairs.
A Cat 5E Wall outlet showing the two wiring schemes: A for T568A, B for T568B.
Cable standard
The specification for Category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95.
These documents specified performance characteristics and test requirements for frequencies of up to 100 MHz.
Category 5[2] cable includes 4 twisted pairs in a single cable jacket. This use of balanced lines helps preserve a
high signal-to-noise ratio despite interference from both external sources and other pairs (this latter form of
interference is called crosstalk). It is most commonly used for 100 Mbit/s networks, such as 100BASE-TX
Ethernet, although IEEE 802.3ab defines standards for 1000BASE-T – Gigabit Ethernet over category 5 cable.
Each of the four pairs in a Cat 5 cable has differing precise number of twists per metre based on prime numbers
to minimize crosstalk between the pairs. On average there are 6 twists per 5 centimetres. The pairs are made
from 24 gauge (AWG) copper wires within the cables.
Connectors and other information
The cable exists in both stranded and solid conductor forms. The stranded form is more flexible and withstands
more bending without breaking and is suited for reliable connections with insulation piercing connectors, but
makes unreliable connections in insulation-displacement connectors. The solid form is less expensive and
makes reliable connections into insulation displacement connectors, but makes unreliable connections in
insulation piercing connectors. Taking these things into account, building wiring (for example, the wiring inside
the wall that connects a wall socket to a central patch panel) is solid core, while patch cables (for example, the
movable cable that plugs into the wall socket on one end and a computer on the other) are stranded. Outer
insulation is typically PVC or LSOH.
Cable types, connector types and cabling topologies are defined by TIA/EIA-568-B. Nearly always, 8P8C
modular connectors, often incorrectly referred to as "RJ-45", are used for connecting category 5 cable. The
specific category of cable in use can be identified by the printing on the side of the cable.[3]
The cable is terminated in either the T568A scheme or the T568B scheme. Canada and Australia use the T568A
standard, and the United States commonly uses T568B scheme. It really doesn't make any difference which is
used as long as you use only one of the standards so all connections are the same at your location to avoid
confusion and potential problems. Mixed cable types should not be connected in series as the impedance per
pair differs slightly and may cause signal degradation. The article Ethernet over twisted pair describes how the
cable is used for Ethernet, including special "cross over" cables.
Conductors required
10BASE-T (IEEE) and 100BASE-TX (IEEE) Ethernet connections require two cable pairs. 1000BASE-T
(IEEE) and 1000BASE-TX (TIA/EIA-854, requiring category 6 cabling) Ethernet connections require four
cable pairs. Four pair cable is by far most commonly available type.
Bending radius
Most Cat.5 cables can be bent at a radius approximately 4 times the diameter of the cable.[4]
Maximum cable segment length
According to the ANSI/TIA/EIA standard for category 5e cable, (TIA/EIA 568-5-A[5]) the maximum length for
a cable segment is 100 meters (328 feet). If longer runs are required, the use of active hardware such as a
repeater, or a switch, is necessary.[6] [7] This 100 meter limit is all inclusive. According to some authors, the
practical limit for permanently installed cable is about 90 meters, leaving 5 meters at each end for the patch
cables that connect the end equipment to the wall panel.
Characteristics
Electrical characteristics for Cat.5e UTP
Property
Nominal Value
Tolerance Unit
Characteristic impedance @ 100 MHz
100 ± 15
Ω
Nominal characteristic impedance @ 100 MHz
100 ± 5
Ω
ref
[8]
[8]
DC-Loop resistance
Propagation speed
Propagation delay
Delay skew < 100 MHz
Capacitance at 800 Hz
Inductance
Cutoff frequency
Max tensile load, during installation
Wire size
Insulation thickness
Maximum current per conductor
Temperature operating
≤ 0.188
0.64
4.80-5.30
< 0.20
52
525
50323
100
AWG-24 (0.205 mm² )
0.245
0.577
-55 to +60
Ω/m
c
ns/m
ns/m
pF/m
nH/m
Hz
N
[8]
[8]
[8]
[8]
[8]
[9]
[9]
[8]
[8][10]
mm
A
°C
[8]
[10]
[8]
Dielectric
Example materials used as dielectric in the cable[11]
Acronym
Material
PE
Polyethylene
FP
Foamed polyethylene
FEP
Teflon/fluorinated ethylene propylene
FFEP
Foamed Teflon/fluorinated ethylene propylene
AD/PE Air dielectric/polyethylene
Individual twist lengths
By altering the length of each twist, crosstalk is reduced, without affecting the characteristic impedance.[9]
Pair color [cm] per turn Turns per [m]
Green
1.53
65.2
Blue
1.54
64.8
Orange
1.78
56.2
Brown
1.94
51.7
Environmental ratings
US & Canada fire certifications[12][13]
Class
Acronym
Standards
[14]
CMP Plenum
CSA FT7
or NFPA 262 [14](UL 910)
CMR Riser
UL 1666
CMG General purpose CSA FT4
CM
UL 1685 (UL 1581, Sec. 1160) Vertical-Tray
CMX Residential
UL 1581, Sec. 1080 (VW-1)
CMH
CSA FT1
Where a CMR can be replaced by a CMP and so on, due to better rating. CM stands for Communications
Cable.[12]
Some cables are "UV rated" or "UV stable" meaning they can be exposed to outdoor UV radiation without
significant destruction. The materials used for the mantle are usually PVC.[15]
Any cable which contains air spaces can breathe in moisture, especially if the cable runs between indoor and
outdoor spaces. Warm moist air can cause condensation inside the colder parts of the cable outdoors. It may be
necessary to take precautions such as sealing the ends of the cables. Some cables are suitable for "direct burial",
but this usually requires that the cable is gel filled in order to hinder moisture migration into the cable.
When using a cable for a tower, attention must be given to vertical cable runs which may channel water into
sensitive indoor equipment.[16] This can often be solved by adding a drip-loop at the bottom of the run of cable.
Plenum rated cables are slower to burn and produce less smoke than cables using a mantle of materials like
PVC. This also affects legal requirements for a fire sprinkler system. That is if a plenum rated cable is used,
sprinkler requirement may be eliminated.[17]
Shielded cables (FTP/STP) are useful for environments where proximity to power cables, RF equipment, or
high power equipment may introduce crosstalk, and can also be used where interference with radio receivers or
where eavesdropping likelihood should be minimised.
Other issues
Copper-clad aluminium
The American market was flooded with copper clad cable imported mostly from China and falsely presented in
the market as being a 100% copper Cat 5e cable. With less copper involved in the manufacturing process, the
cost to the consumer is lower, yet the consumer is not getting a true 100% copper Cat 5e cable.
Installation of copper clad aluminium Cat 5e wire was proven — by low-voltage contractors in the Southern
California market, where this cable first arrived — to have poor test results and often did not pass the Category
5e transmission standard. Since copper conducts electricity better than aluminium, signal strength has shown to
be very weak over long runs using this substandard cable.
Additionally, some manufacturers falsely represented their Cat 5e cable conductors as being 24 AWG. In
actuality, a 26 AWG conductor is being sold and is hard to detect unless further examination beneath the sheath
of the conductor is performed. A 26 AWG Cat 5e cable will not make proper contact on Cat 5e jack modules as
most jack modules require 22 or 24 AWG per the specification and qualified connectors.[18]
The United States Federal Government will not accept bids from China for Cat 5e cable due to China being
absent from the Trade Agreements Act of 1979. In general, a product is only "TAA compliant" if it is made in
the United States or a "Designated Country".
The Cat 5e "350 MHz" debacle
The 350 MHz term started a couple of years before the arrival of Category 6 cable by the Belden Electronics
Division and promised better performance. Although the performance of this new 350 MHz cable was slightly
better it was an easy way to sell the consumer on future proofing their needs while charging around 15% more
and leading to a higher margin on the 350 MHz cable than the standard 5e cable. Soon after many other
manufactures also offered a 350 MHz cable and followed the trend of an easy way to add to a higher margin.
Some low-end cable manufacturers have the term "tested to 350 MHz" printed on the jacket as a way to appear
to the consumer that they are receiving a better quality of 5e cable, but the cable was only "tested to 350 MHz"
and no promise of a performance guarantee is ever mentioned.
As the 350 cable and term gained momentum, many manufacturers began offering a 400 MHz 5e cable,[19] a
550 MHz 5e cable, and so on. This led to the consumer and communications contractor assuming and leaving
them confused that the higher a MHz rating meant for a better performing cable. The arrival of the Category 6
cable standard which specified a delivered performance at 250 MHz left many people confused.
Electronic Industries Alliance/Telecommunications Industry Association (EIA/TIA) only recognize the
Category 5e standard TIA/EIA-568-B.2-2001 as guaranteeing performance of attenuation, NEXT, power-sum
NEXT, ACR, power-sum ACR, ELFEXT, power-sum ELFEXT, return loss, propagation delay and delay skew
at 100 MHz. No standard is issued for 350 MHz cable and review of manufacturer specification sheets such as
General Cable,[20] Superior Essex,[21] and Berktek[22] show us different performance numbers for 350 MHz.
With no standard for 350 MHz cable, promised performance, if any, will vary from manufacturer to
manufacturer and leave the consumer and contractor to continue to be confused.
See also






Category 3 cable
Category 4 cable
Category 6 cable
Category 7 cable
Ethernet over twisted pair (10/100/1000Base-T)
Power over Ethernet (PoE)
References
1. ^ "ANSI/TIA/EIA-568-B.1-2001 Approved: April 12, 2001 ; Commercial Building
Telecommunications Cabling Standard Part 1: General Requirements".
http://www.nag.ru/goodies/tia/TIA-EIA-568-B.1.pdf. 090917 nag.ru
2. ^ "Category 5 - TIA's Glossary of Telecommunication Terms".
http://www.tiaonline.org/market_intelligence/glossary/index.cfm?term=%25%22T%5FQR%22%24%2
0%0A. 090524 tiaonline.org
3. ^ Ethernet Cable Identification and Use
4. ^ "Selecting coax and twisted-pair cable - Electronic Products".
http://www2.electronicproducts.com/Selecting_coax_and_twisted-pair_cable-article-belden-nov2005html.aspx. 081216 www2.electronicproducts.com
5. ^ "The Evolution of Copper Cabling Systems from Cat5 to Cat5e to Cat6".
http://www.gocsc.com/UserFiles/File/Panduit/Panduit098765.pdf.www.panduit.com
6. ^ "UTP technology by Extron Technologies". http://www.extron.com/download/files/whitepaper/cat5white.pdf. www.extron.com
7. ^ "Cat5e Cable Wiring Schemes White Paper by B&B Electronics". http://bbelec.com/tech_articles/NTRON_cat5e_cable_wiring_schemes.asp. bb-elec.com
8. ^ a b c d e f g h i j k "SuperCat OUTDOOR CAT 5e U/UTP".
http://www.draka.com/draka/Countries/Draka_Norway/Languages/Norsk/Navigation/Produkter/Databla
der/Kategorikabel/NO_Cat_5_AWG_24_U_UTP_OUTDOOR.pdf. 080319 draka.com
9. ^ a b c "Transmission Line Zo". http://www.prc68.com/I/Zo.shtml. 090113 prc68.com
10. ^ a b "American Wire Gauge table and AWG Electrical Current Load Limits".
http://www.powerstream.com/Wire_Size.htm. 081220 powerstream.com
11. ^ "UL Listed / ISO 9001 Compliant". http://unioncopper.com/. 090127 unioncopper.com
12. ^ a b "CSA Flame Test Ratings".
http://74.125.77.132/search?q=cache:lj1qDZvjxDAJ:www.kqtcable.com/inc.php%3Finc%3Dinfo-CSAFlame-Test-Ratings&hl=sv&ct=clnk&cd=2. 090126 74.125.77.132
13. ^ "22Technical Information" (PDF).
http://www.belden.com/pdfs/03Belden_Master_Catalog/22Technical%2520Information_Glossary/22Te
chnical_Information.pdf.[dead link] 090126 belden.com
14. ^ a b http://cat6wiring.com/cat6-plenum-cable.php
15. ^ "CAT5e CMR/CMX mean it's uv rated ? - dslreports.com".
http://www.broadbandreports.com/forum/remark,16168746. 090126 broadbandreports.com
16. ^ "A dumb mistake a green WISP operator once made. - dslreports.com".
http://www.broadbandreports.com/forum/r21017727-A-dumb-mistake-a-green-WISP-operator-oncemade. 090126 broadbandreports.com
17. ^ "What are the differences between PVC, riser and plenum rated cables? - Ask or Answer Questions on
Computers & Technology, Ask & Read old Answers on Computers & Technology - ibibo sawaal".
http://sawaal.ibibo.com/computers-and-technology/oldest-answers/what-are-the-differences-betweenpvc-riser-and-plenum-rated-cables-154825.html. 090126 sawaal.ibibo.com
18. ^ "Cat5E 90 deg HD Data Jack Module". http://lib.store.yahoo.net/lib/yhst62665683816747/File0003.pdf. 090901 lib.store.yahoo.net TIA/EIA-568-B.2 compliant data jack
19. ^ Tested to 400 MHz
20. ^ 350 General Spec Sheet
21. ^ Superior Essex 350 spec sheet
22. ^ Berktek 350 Spec sheet
Further reading






DIY Step-by-Step Instructions on making Cat5e Cables - Pictures and Video
Discount-Low-Voltage.com Blog - How Cat5e Cable is Made
cat5ecables.co.uk - CAT5e cable information, colour codes and pinouts, learn how to make patch leads
mikestechblog.com - How to make your own Cat5 cable
unioncopper.com - Cable exploded view and which materials used
computercablestore.com - How to make Cat5e patch cables - Detailed step by step
Unshielded and shielded twisted pair cabling standards










Cat 1: Currently unrecognized by TIA/EIA. Previously used for POTS telephone communications,
ISDN and doorbell wiring.
Cat 2: Currently unrecognized by TIA/EIA. Previously was frequently used on 4 Mbit/s token ring
networks.
Cat 3: Currently defined in TIA/EIA-568-B, used for data networks using frequencies up to 16 MHz.
Historically popular for 10 Mbit/s Ethernet networks.
Cat 4: Currently unrecognized by TIA/EIA. Defined up to 20 MHz, and was frequently used on
16 Mbit/s token ring networks.
Cat 5: Currently unrecognized by TIA/EIA. Defined up to 100 MHz, and was frequently used on
100 Mbit/s Ethernet networks. May be unsuitable for 1000BASE-T gigabit ethernet.
Cat 5e: Currently defined in TIA/EIA-568-B. Defined up to 100 MHz, and is frequently used for both
100 Mbit/s and 1000BASE-T Gigabit Ethernet networks.
Cat 6: Currently defined in TIA/EIA-568-B. Defined up to 250 MHz, more than double category 5 and
5e.
Cat 6a: Currently defined in ANSI/TIA/EIA-568-B.2-10 and Amendment 1 and 2 of ISO/IEC 11801.
Defined up to 500 MHz, nearly double that of category 6. Suitable for 10GBASE-T.
Cat 7: Currently defined in ISO/IEC 11801 Class F cabling. Defined up to 600 MHz. This standard
specifies four individually-shielded pairs (S/FTP) inside an overall shield.
Cat 7a: Currently defined in Amendment 1 and 2 of ISO/IEC 11801 Class FA cabling. Defined up to
1,000 MHz. Cable constructions is S/FTP.
Category 6 cable
From Wikipedia, the free encyclopedia
Category 6 cable, commonly referred to as Cat.-6, is a cable standard for Gigabit Ethernet and other network
protocols that are backward compatible with the Category 5/5e and Category 3 cable standards. Compared with
Cat.-5 and Cat.-5e, Cat.-6 features more stringent specifications for crosstalk and system noise. The cable
standard provides performance of up to 250 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet),
1000BASE-T/1000BASE-TX (Gigabit Ethernet) and 10GBASE-T (10-Gigabit Ethernet). Category 6 cable has
a reduced maximum length when used for 10GBASE-T; Category 6a cable, or Augmented Category 6, is
characterized to 500 MHz and has improved alien crosstalk characteristics, allowing 10GBASE-T to be run for
the same distance as previous protocols. Category 6 cable can be identified by the printing on the side of the
cable sheath.[1]
Category 6
Like most earlier cables, Category 6 cable contains four twisted wire pairs. Although it is sometimes made with
23 AWG wire, the increase in performance with Cat.-6 comes mainly from better insulation; 22 to 24 AWG
copper is allowed if the ANSI/TIA-568-B.2-1 performance specifications are met. Cat.-6 patch cables are
normally terminated in 8P8C (often incorrectly called RJ-45) modular connectors. Attenuation, NEXT (near
end crosstalk), and PSNEXT (power sum NEXT) in Cat.-6 cable and connectors are all significantly lower than
Cat.-5/5e, which also uses 24 AWG wire.
The heavier insulation in some Cat.-6 cables makes them too thick to attach to 8P8C connectors without a
special modular piece, resulting in a technically out-of-compliance assembly.
Connectors use either T568A or T568B pin assignments; the choice is arbitrary provided both ends of a cable
are the same. Both schemes use straight-through wiring (pin 1 to 1, pin 2 to 2, etc) and the same pairing (pins
1&2, 3&6, 4&5, 7&8). Only the wire colors differ, which is of no concern outside the cable. This makes T568A
and T568B patch cords interchangeable, with T568B being the most common.
If Cat.-6 rated patch cables, jacks, and connectors are not used with Cat.-6 wiring, overall performance is
degraded to that of the cable or connector. Because the conductor sizes are generally the same, Cat.-6 jacks may
also be used with Cat.-5e cable.
Because all 1000BASE-T (gigabit Ethernet) equipment supports automatic crossover (auto-MDIX), Cat.-6
crossover cables are rare. Crossover cables are sometimes needed between 10/100 Mb/s devices where neither
endpoint supports auto-MDIX, but Cat.-5 is sufficient for these slower speeds.
Pins on 8P8C plug face
8P8C Wiring (T568A termination)
Pin Pair Wire
Color
1 3
1
white/green
2
3
2
green
3
2
1
white/orange
4
1
2
blue
5
1
1
white/blue
6
2
2
orange
7
4
1
white/brown
8
4
2
brown
8P8C Wiring (T568B termination)
Pin Pair Wire
Color
1 2
1
white/orange
2
2
2
orange
3
3
1
white/green
4
1
2
blue
5
1
1
white/blue
6
3
2
green
7
4
1
white/brown
8
4
2
brown
USOC/RJ61 Wiring
Pin Pair Wire
Color
1 4
1
white/brown
2
3
1
white/green
3
2
1
white/orange
4
1
2
blue
5
1
1
white/blue
6
2
2
orange
7
3
2
green
8
4
2
brown
Category 6a
The latest standard from the TIA for enhanced performance standards for twisted pair cable systems was
defined in February 2008 in ANSI/TIA/EIA-568-B.2-10. Category 6a (or Augmented Category 6) is defined
at frequencies up to 500 MHz—twice that of Cat. 6.
Category 6a performs at improved specifications, particularly in the area of alien crosstalk as compared to Cat.6 UTP which exhibited high alien noise in high frequencies.
The global cabling standard ISO/IEC 11801 will soon be extended by the addition of amendment 2. This
amendment defines new specifications for Cat. 6A components and Class EA permanent links. These new
global Cat. 6A/Class EA specifications require a new generation of connecting hardware offering far superior
performance compared to the existing products which are based on the American TIA standard.
The most important point is a performance difference between ISO/IEC and EIA/TIA component specifications
for the NEXT transmission parameter. At a frequency of 500 MHz, an ISO/IEC Cat. 6A connector performs 3
dB better than a Cat. 6A connector that conforms with the EIA/TIA specification. 3 dB equals 100% increase of
near-end crosstalk noise reduction when measured in absolute magnitudes.[2]
TIA comp. Cat. 6A ≠ ISO/IEC Cat. 6 A comp.3[3]
Maximum length
The maximum allowed length of a Cat.-6 cable is 100 meters (330 ft) when used for 10/100/1000BASE-T. This
consists of 90 meters (300 ft) of solid "horizontal" cabling between the patch panel and the wall jack, plus
10 meters (33 ft) of stranded patch cable between each jack and the attached device. Since stranded cable has
higher attenuation than solid cable, exceeding 10 metres of patch cabling will reduce the permissible length of
horizontal cable.
When used for 10GBASE-T, Cat.-6 cable's maximum length is 55 meters (180 ft) in a favourable alien
crosstalk environment, but only 37 meters (121 ft) in a hostile alien crosstalk environment such as when many
cables are bundled together. 10GBASE-T runs of up to 100 meters (330 ft) are permissible using Cat.-6a.
Installation caveats
Category 6 and 6a cable must be properly installed and terminated to meet specifications. Incorrect installation
practices include kinking the cable or bending it with too tight a radius. Incorrect termination practices include
untwisting the wire pairs or stripping the outer jacket back too far.
All shielded cables must be grounded at both ends in order for the shield to offer full effectiveness.[4]
Unshielded Category 6a cable does not have this limitation, but has a larger diameter.
To ensure that an installation will meet the requirements for the network protocol it will be used for, a new
installation is usually certified using a so-called cable certifier, validator or qualification tester.
References
1.
2.
3.
4.
^ Ethernet Cable Identification and Use
^ Details about TIA and ISO Cat 6a
^ Cabling: The Complete Guide to Network Wiring, 3rd Edition
^ TIA/EIA 568C, ISO 11801 and BICSI TDMM
External links





"10 Gb/s Over Copper: Horizontal Cabling Choices". The Siemon Company. 2006-01-10.
http://www.siemon.com/us/white_papers/06-01-10_10G-horizontal-cabling-choices.asp. Information on
cable construction and alien crosstalk mitigation.
Schmidt, John (March/April 2007). "Determining the Right Media" (PDF). BICSI News 28 (2).
http://www.adc.com/us/en/productsandservices/truenet/media/Determining_the_Right_Media.pdf.
Information on TIA TSB-155 37m versus IEEE 55m limitations.
"What are CAT6 Cables?". KSM Limited. http://www.cat6cables.co.uk/index.html.
"How to Make an Ethernet Cat5e/Cat6 Cable". Cable & Wireless Technologies, Inc.. 2009-10-14.
http://discountlowvoltage.blogspot.com/2009/10/how-to-make-ethernet-cat5e-cable.html.
"How to Terminate Cat6a Shielded Keystone Jacks". Cable & Wireless Technologies, Inc.. 2009-12-09.
http://discountlowvoltage.blogspot.com/2009/12/how-to-terminate-cat6a-shielded.html.


"How Category 6 Cable is Made". Cable & Wireless Technologies, Inc.. 2009-11-05.
http://discountlowvoltage.blogspot.com/2009/11/how-low-voltage-cable-is-made-cat5e.html.
"How to Build Cat 6 Patch Cables - Step by Step with Detailed Photos". ComputerCableStore.com.
2007-10-11. http://www.computercablestore.com/cat6-patch-cables1.aspx.
Category 7 cable
From Wikipedia, the free encyclopedia
Category 7 cable
Category 7 cable (Cat 7), (ISO/IEC 11801:2002 category 7/class F), is a cable standard for Ethernet and other
interconnect technologies that can be made to be backward compatible with traditional Cat 5 and Cat 6 Ethernet
cable. Cat 7 features even more strict specifications for crosstalk and system noise than Cat 6. To achieve this,
shielding has been added for individual wire pairs and the cable as a whole. Category 7 is recognized for all the
country organizations members of ISO.
The Cat 7 cable standard has been created to allow 10 Gigabit Ethernet over 100 m of copper cabling (also, 10Gbit/s Ethernet now is typically run on Cat 6a). The cable contains four twisted copper wire pairs, just like the
earlier standards. Cat 7 can be terminated either with 8P8C compatible GG45 electrical connectors which
incorporate the 8P8C standard or with TERA connectors. When combined with GG45 or TERA connectors,
Cat 7 cable is rated for transmission frequencies of up to 600 MHz.
As of November 2010, all manufacturers of active equipment have chosen to support the 8P8C for their 10
Gigabit Ethernet products on copper, and not the GG45 or TERA in order to function on Cat 6a. Due to lack of
support for the 8P8C connector, Category 7 is not recognized in TIA/EIA-568.
Category 7a
Category 7a (or Augmented Category 7) is defined at frequencies up to 1000 MHz, suitable for multiple
applications in a single cable (just like all other categories) including CATV (862 MHz).[1][2][3] Simulation
results have shown that 40 Gigabit Ethernet is possible at 50 meters and 100 Gigabit Ethernet is possible at 15
meters.[1] Mohsen Kavehrad and researchers at The Pennsylvania State University believe that either 32 nm or
22 nm circuits will allow for 100 Gigabit Ethernet at 100 meters.[4][5]
However, similar studies in the past have shown that Cat5e could support 10 Gbps, so these should be read with
caution. Furthermore, the IEEE has chosen not to include Cat7a for 40 Gbps or 100 Gbps in the new 802.3ba
standard ratified in June 2010. It may in the future, but there is absolutely no guarantee that such applications
will ever exist.
Cat7a is currently in ISO standards for channel performance in Amendment 1, recently component performance
has been ratified in Amendment 2. The formal names are ISO 11801 Amendment 1 (2008) and ISO 11801
Amendment 2 (2010). Category 7a is not recognized in TIA/EIA-568.
References
1. ^ a b "DesignCon 2009: 40/100 Gbps Transmission Over Copper". Techonline. 2009-02-01.
http://www.techonline.com/learning/techpaper/213001693. Retrieved 2009-02-28.
2. ^ "Patch cords with integrated baluns enable multi- HD video support". Cabling Installation &
Maintenance. 2008-04-30.
http://cim.pennnet.com/display_article/327273/27/NEWS/none/TOPST/1/Patch-cords-with-integratedbaluns-enable-multi--HD-video-support/. Retrieved 2009-02-28.[dead link]
3. ^ "New Siemon Patch Cords with Integrated Baluns Provide Single-Outlet Support of Multiple HighDefinition Video Signals". Siemon. 2008-04-28.
http://www.siemon.com/us/company/press_releases/08-04-28-tera-balun.asp. Retrieved 2009-02-28.
4. ^ News release
5. ^ "UPDATE: Cat-7 copper theorized to transmit 100 Gbps in excess of 100 meters using future
modems". TGDaily. 2007-11-14. http://www.tgdaily.com/content/view/34854/113/. Retrieved 2009-0228.

De-Mystifying Cabling Specifications From 5e to 7A
Ethernet over twisted pair
From Wikipedia, the free encyclopedia
Twisted-pair cable used with 10BASE-T
8P8C plug used with 10BASE-T
Ethernet over twisted pair refers to the use of cables that contain insulated copper wires twisted together in
pairs for the physical layer of an Ethernet network—that is, a network in which the Ethernet protocol provides
the data link layer. Other Ethernet cable standards use coaxial cable or optical fiber. There are several different
standards for this copper-based physical medium. The most widely used are 10BASE-T, 100BASE-TX, and
1000BASE-T, running at 10 Mbit/s (also Mbps or Mbs-1), 100 Mbit/s, and 1000 Mbit/s (1 Gbit/s), respectively.
These three standards all use the same connectors. Higher speed implementations nearly always support the
lower speeds as well, so that in most cases different generations of equipment can be freely mixed. They use 8
position modular connectors, usually called RJ45 in the context of Ethernet over twisted pair. The cables
usually used are four-pair twisted pair cable (though 10BASE-T and 100BASE-TX only actually require two of
the pairs). Each of the three standards support both full-duplex and half-duplex communication.
The common names for the standards derive from aspects of the physical media. The number refers to the
theoretical maximum transmission speed in megabits per second (Mbit/s). The BASE is short for baseband,
meaning that there is no frequency-division multiplexing (FDM) or other frequency shifting modulation in use;
each signal has full control of wire, on a single frequency. The T designates twisted pair cable, where the pair
of wires for each signal is twisted together to reduce radio frequency interference and crosstalk between pairs
(FEXT and NEXT). Where there are several standards for the same transmission speed, they are distinguished
by a letter or digit following the T, such as TX.
Cabling
Twisted-pair Ethernet standards are such that the majority of cables can
be wired "straight-through" (pin 1 to pin 1, pin 2 to pin 2 and so on),
but others may need to be wired in the "crossover" form (receive to
transmit and transmit to receive).
10BASE-T and 100BASE-TX only require two pairs to operate, located
on pins 1 plus 2 and pins 3 plus 6. Since 10BASE-T and 100BASE-TX
need only two pairs and Category 5 cable has four pairs, it is possible,
but not standards compliant, to run two network connections (or a
network connection and two phone lines) over a Category 5 cable by
using the normally unused pairs (pins 4–5, 7–8) in 10- and 100-Mbit/s
configurations. In practice, great care must be taken to separate these
pairs as most 10/100-Mbit/s hubs, switches and PCs internally hardwire
pins 4–5 together and pins 7–8 together, thereby creating a short-circuit
across each "unused" pair. Moreover, 1000BASE-T requires all four
pairs to operate, pins 1 and 2, 3 and 6 — as well as 4 and 5, 7 and 8.
8P8C modular plug pin positioning
It is conventional to wire cables for 10- or 100-Mbit/s Ethernet to either
the T568A or T568B standards. Since these standards differ only in that
they swap the positions of the two pairs used for transmitting and
receiving (TX/RX), a cable with T568A wiring at one end and T568B
wiring at the other is referred to as a crossover cable. The terms used in
the explanations of the 568 standards, tip and ring, refer to older
communication technologies, and equate to the positive and negative
parts of the connections.
A 10BASE-T or 100BASE-T node such as a PC also called MDI that
transmits on pin 1 and 2 and receives on pin 3 and 6 to a network
device uses a "straight-through" cable in the MDI wiring pattern. A
straight-through cable is usually used to connect a node to its network
device. In order for two network devices or two nodes to communicate
with each other (such as a switch to another switch or computer to
computer) a crossover cable is often required at speeds of 10 or
100 Mbit/s. If available, connections can be made with a straightthrough cable by means of an MDI-X port, also known as an "internal
crossover" or "embedded crossover" connection. Hub and switch ports
with such internal crossovers are usually labelled as such, with "uplink"
or "X". For example, 3Com usually labels their ports 1X, 2X, and so
on. In some cases a button is provided to allow a port to act as either a
normal or an uplink port.
TIA/EIA-568-B T568A Wiring
Pin Pair Wire
Color
1 3
tip
white/green
2
3
ring
green
3
2
tip
white/orange
4
1
ring
blue
5
1
tip
white/blue
6
2
ring
orange
7
4
tip
white/brown
8
4
ring
brown
TIA/EIA-568-B T568B Wiring
Pin Pair Wire
Color
1 2
tip
white/orange
2
2
ring
orange
3
3
tip
white/green
4
1
ring
blue
5
1
tip
white/blue
6
3
ring
green
To connect two computers directly together without a switch, an
7 4
tip
white/brown
Ethernet crossover cable is often used. Although many modern Ethernet
ring
brown
host adapters can automatically detect another computer connected with 8 4
a straight-through cable and then automatically introduce the required
crossover, if needed; if neither of the computers have this capability, then a crossover cable is required. If both
devices being connected support 1000BASE-T according to the standards, they will connect regardless of the
cable being used or how it is wired.
To connect two hubs or switches directly together, a crossover cable can be used, but some hubs and switches
have an uplink port used to connect network devices together, or have a way to manually select MDI or MDI-X
on a single port so that a straight-through cable can connect that port to another switch or hub. Most newer
switches have automatic crossover ("auto MDI-X" or "auto-uplink") on all ports, eliminating the uplink port
and the MDI/MDI-X switch, and allowing all connections to be made with straight-through cables.
A 10BASE-T transmitter sends two differential voltages, +2.5 V or −2.5 V.
100BASE-TX follows the same wiring patterns as 10BASE-T but is more sensitive to wire quality and length,
due to the higher bit rates.
A 100BASE-TX transmitter sends three differential voltages, +1 V, 0 V, or −1 V[1].
1000BASE-T uses all four pairs bi-directionally and the standard includes auto MDI-X; however,
implementation is optional. With the way that 1000BASE-T implements signaling, how the cable is wired is
immaterial in actual usage. The standard on copper twisted pair is IEEE 802.3ab for Cat 5e UTP, or 4D-PAM5;
four dimensions using PAM (pulse amplitude modulation) with five voltages, −2 V, −1 V, 0 V, +1 V, and +2 V
[2]
While +2 V to −2 V voltage may appear at the pins of the line driver, the voltage on the cable is nominally
+1 V, +0.5 V, 0 V, −0.5 V and −1 V[3].
Unlike earlier Ethernet standards using broadband and coaxial cable, such as 10BASE5 (thicknet) and
10BASE2 (thinnet), 10BASE-T does not specify the exact type of wiring to be used but instead specifies certain
characteristics that a cable must meet. This was done in anticipation of using 10BASE-T in existing twistedpair wiring systems that may not conform to any specified wiring standard. Some of the specified
characteristics are attenuation, characteristic impedance, timing jitter, propagation delay, and several types of
noise. Cable testers are widely available to check these parameters to determine if a cable can be used with
10BASE-T. These characteristics are expected to be met by 100 meters of 24-gauge unshielded twisted-pair
cable, and 100 meters is the stated maximum length for baseband signal runs. However, with high quality
cabling, cable runs of 150 meters or longer are often obtained and are considered viable by most technicians
familiar with the 10BASE-T specification, though – as with all CSMA/CD network environments – the
absolute limit on run length is determined by the size of the collision domain and cable quality. In reality, what
meets the standards may not work, and those that do not meet the standards might work.
100BASE-TX and 1000BASE-T were both designed to require a minimum of Category 5 cable and also
specify a maximum cable length of 100 meters, though in practice category 5e or above is generally
recommended for 1000BASE-T. Furthermore while 10BASE-T is more tolerant of poor wiring such as split
pairs, poor terminations and even use of short sections of flat cable, 100BASE-T is less tolerant, and
1000BASE-T is even less so. Since cable testing is often limited to checking if a connection works with
Ethernet, running faster speeds over existing cable is often problematic. This problem is made worse by the fact
that Ethernet's auto-negotiation takes account only of the capabilities of the end equipment, not of the cable in
between.
Autonegotiation and duplex mismatch
Many different modes of operations (10BASE-T half duplex, 10BASE-T full duplex, 100BASE-TX half
duplex, ...) exist for Ethernet over twisted pair, and most network adapters are capable of different modes of
operation. In 1995, a standard was released to allow connected network adapters to negotiate the best possible
shared mode of operation. The autonegotiation standard contained a mechanism for detecting the speed but not
the duplex setting of Ethernet peers that did not use autonegotiation.
When two linked interfaces are set to different duplex modes, the effect of this duplex mismatch is a network
that functions much more slowly than its nominal speed.
Duplex mismatch may be inadvertently caused when an administrator configures an interface to a fixed mode
(e.g. 100 Mbit/s full duplex) and fails to configure the remote interface, leaving it set to autonegotiate. Then,
when the autonegotiation process fails, half duplex is assumed by the autonegotiating side of the link.
The resulting duplex mismatch results in a dramatically slow network, in which many collisions, and especially
late collisions occur on the interface set to half-duplex, and FCS errors are seen on the full-duplex side. [4]
Gigabit Ethernet standards require autonegotiation to be on in order to operate.
Higher speeds
Speed
Distance [m]
[Mbit/s]
Name
Standard
/ Year
Description
Runs over four wires (two twisted pairs) on a Category 3
or Category 5 cable. An active hub or switch sits in the
802.3
(14)
middle and has a port for each node. This is also the
10 Unspecified[5] 10BASE-T
[6]
1990
configuration used for 100BASE-T and gigabit Ethernet.
Manchester coded signaling, copper twisted pair cabling,
star topology - direct evolution of 1BASE-5.
802.3 (24) 4B5B MLT-3 coded signaling, CAT5 copper cabling
100
100 100BASE-TX
1995
with two twisted pairs.
PAM-5 coded signaling, At least Category 5 cable, with
802.3 (40) Category 5e strongly recommended copper cabling with
1000
100 1000BASE-T
1999[7]
four twisted pairs. Each pair is used in both directions
simultaneously.
802.3an
10 000
100 10GBASE-T
Uses unshielded twisted-pair wiring.
2006
802.3ba
40 000
10 40GBASE-CR4
10 m operation copper cable assembly.
2010?
802.3ba
100 000
10 100GBASE-CR10
10 m operation copper cable assembly.
2010
References
1. ^ http://books.google.com/books?id=392CdZHdUDEC&pg=PA240&lpg=PA240&dq=%22100BASETX%22+2V+voltage&source=web&ots=Jtyqtz0KE6&sig=AnR2pHk04YgKKlYAvTiEheQAlHU&hl=
en&sa=X&oi=book_result&resnum=8&ct=result
2. ^ http://grouper.ieee.org/groups/802/3/minutes/july98/E2_0798.pdf
3. ^ "Voltage-mode line drivers save on power " 2004
4. ^ Ethernet Autonegotiation Best Practices
5. ^ Gary A. Donahue (2007-06). Network Warrior. O'Reilly. p. 6. "...the 10Base-T spec instead describes
certain characteristics that a cable should meet."
6. ^ http://shuntek.com/presentations/CCNA1/English/CCNA1V3_1_MODULE_7.PDF
7. ^
http://www.trendcomms.com/multimedia/training/broadband%20networks/web/main/Ethernet/Theme/C
hapter2/1000BASE-T%20Architecture.html
Further reading


IEEE 802.3 standards documents
UTP cable termination standards 568A vs 568B
External links




How to Make a Network Cable, a how-to article from wikiHow.
How to create your own Ethernet Cables
How to wire a 10Base-T or 100Base-T connector with category 5 cable and 8P8C modular connectors
Step by step instructions on how to punch down category 5e cable to a RJ45
How to Make a Network Cable
The steps below are general Ethernet Category 5 (commonly known as Cat 5) cable construction guidelines.
For our example, we will be making a Category 5e patch cable, but the same general method will work for
making any category of network cables.
Steps
1. 1
Unroll the required length of network cable and add a little extra wire, just in case. If a boot is to
be fitted, do so before stripping away the sleeve and ensure the boot faces the correct way.
2. 2
Carefully remove the outer jacket of the cable. Be careful when stripping the jacket as to not nick or
cut the internal wiring. One good way to do this is to cut lengthwise with snips or a knife along the side
of the cable, away from yourself, about an inch toward the open end. This reduces the risk of nicking the
wires' insulation. Locate the string inside with the wires, or if no string is found, use the wires
themselves to unzip the sheath of the cable by holding the sheath in one hand and pulling sideways with
the string or wire. Cut away the unzipped sheath and cut the twisted pairs about 1 1/4" (30 mm). You
will notice 8 wires twisted in 4 pairs. Each pair will have one wire of a certain color and another wire
that is white with a colored stripe matching its partner (this wire is called a tracer).
3. 3
Inspect the newly revealed wires for any cuts or scrapes that expose the copper wire inside. If you
have breached the protective sheath of any wire, you will need to cut the entire segment of wires off and
start over at step one. Exposed copper wire will lead to cross-talk, poor performance or no connectivity
at all. It is important that the jacket for all network cables remains intact.
4. 4
Untwist the pairs so they will lay flat between your fingers. The white piece of thread can be cut off
even with the jacket and disposed (see Warnings). For easier handling, cut the wires so that they are
3/4" (19 mm) long from the base of the jacket and even in length.
5. 5
Arrange the wires based on the wiring specifications you are following. There are two methods set
by the TIA, 568A and 568B. Which one you use will depend on what is being connected. A straightthrough cable is used to connect two different-layer devices (e.g. a hub and a PC). Two like devices
normally require a cross-over cable. The difference between the two is that a straight-through cable has
both ends wired identically with 568B, while a cross-over cable has one end wired 568A and the other
end wired 568B.[1] For our demonstration in the following steps, we will use 568B, but the instructions
can easily be adapted to 568A.
o
568B - Put the wires in the following order, from left to right:








o
white orange
orange
white green
blue
white blue
green
white brown
brown
568A - from left to right: white/green, green, white/orange, blue, white/blue, orange,
white/brown, brown. You can also use the mnemonic 1-2-3-6/3-6-1-2 to remember which wires
are switched.
6. 6
Press all the wires flat and parallel between your thumb and forefinger. Verify the colors have
remained in the correct order. Cut the top of the wires even with one another so that they are 1/2" (12.5
mm) long from the base of the jacket, as the jacket needs to go into the 8P8C connector by about 1/8",
meaning that you only have a 1/2" of room for the individual cables. Leaving more than 1/2" untwisted
can jeopardize connectivity and quality. Ensure that the cut leaves the wires even and clean; failure to
do so may cause the wire not to make contact inside the jack and could lead to wrongly guided cores
inside the plug.
7. 7
Keep the wires flat and in order as you push them into the RJ-45 plug with the flat surface of the
plug on top. The white/orange wire should be on the left if you're looking down at the jack. You can
tell if all the wires made it into the jack and maintain their positions by looking head-on at the plug. You
should be able to see a wire located in each hole, as seen at the bottom right. You may have to use a
little effort to push the pairs firmly into the plug. The cabling jacket should also enter the rear of the jack
about 1/4" (6 mm) to help secure the cable once the plug is crimped. You may need to stretch the sleeve
to the proper length. Verify that the sequence is still correct before crimping.
8. 8
Place the wired plug into the crimping tool. Give the handle a firm squeeze. You should hear a
ratcheting noise as you continue. Once you have completed the crimp, the handle will reset to the open
position. To ensure all pins are set, some prefer to double-crimp by repeating this step.
9. 9
Repeat all of the above steps with the other end of the cable. The way you wire the other end (568A
or 568B) will depend on whether you're making a straight-through, rollover, or cross-over cable (see
Tips).
10. 10
Test the cable to ensure that it will function in the field. Mis-wired and incomplete network cables
could lead to headaches down the road. In addition, with power-over-Ethernet (PoE) making its way
into the market place, crossed wire pairs could lead to physical damage of computers or phone system
equipment, making it even more crucial that the pairs are in the correct order. A simple cable tester can
quickly verify that information for you. Should you not have a network cable tester on hand, simply test
connectivity pin to pin.
Tips




A key point to remember in making Ethernet patch cords is that the "twists" in the individual pairs
should remain entwined as long as possible until they reach the RJ-45 plug termination. The twisting of
the pairs in the network cable is what helps to ensure good connectivity and keeps cross-talk
interference to a minimum. Do not untwist the wires any more than you need to.
CAT5 and CAT5e are very similar cables, however CAT5e offers better quality especially on longer
runs. If making a longer run, CAT5e is recommended, however CAT5 is still an option for small patch
cables.
A good idea on the long runs, especially those that you need to hang or snake around, is to crimp and
test the cable before you run the cable. This is recommended especially to anyone who is first starting
out crimping their own cables, as it ensures you are crimping the correct pin order now, rather than
trying to trouble shoot later.
Always keep a box of Network Cable resting on one of the four 'end' surfaces, never on one of its two
sides. This prevents loops falling across each other inside the box causing binding and knots.
Warnings

The ripcords, if present, are usually quite strong, so do not attempt to break them. Cut them.





Unless you need to do a large amount of cabling work, it may be less frustrating and, due to the cost of
tools, less expensive to purchase ready-made cables.
Fire Codes require a special type of cover over the wires if the cabling is to be installed in ceilings or
other areas that are exposed to the building ventilation system. This is usually referred to as plenumgrade cable or simply "plenum cable", and does not release toxic fumes when burned. Plenum cabling is
more costly, perhaps double that of ordinary cable, so only use where necessary. Riser cable is similar to
plenum, but is for use in walls or wiring closets to connect floors. Riser may not replace plenum cable
so be aware of what area you are laying your cable. If in doubt, use plenum as it has the strictest and
safest ratings.
A cat5 cable can not exceed 100 meters, or 328 feet. It probably shouldn't go beyond 300 feet.
RJ-45 is the common term most individuals use for the connectors present in CAT5 cabling. The correct
name of the connector is simply 8P8C, where as RJ-45 is the name of a very similar looking defunct
connector used in telecommunication. Most people will understand RJ-45 as 8P8C, but be careful when
purchasing out of a catalog or online where you can't visibly determine which you are purchasing.
Be aware of any shielding your cable may have. The most common type of cable is UTP (Unshielded
Twisted Pair), but a number of shielding/foiling options exist for added protection against EMI. Be
aware of what you are purchasing and what you need. In most environments, UTP will be fine.
Things You'll Need




Crimper - This is the most essential tool and critical to the cable making process. If you don't have a
quality crimper, then your cable connections will be bad. Inferior crimpers will make it difficult and/or
nearly impossible to achieve a tight connection between the wires. Many better quality crimpers also
have a ratcheting controlled closure for precise crimping. Crimpers with a plastic body will be more
likely to develop a sloppy hip joint and give consistently poor cramps; a metal crimper is much
preferred, and very common.
Tester (Optional) - Although not necessary for making cables, having a good cable tester can prevent
and solve cable wiring configuration and installation problems. Most testers consist of two boxes
(transmitter and receiver) you plug your patch cable into. The transmitter box tests the cable by sending
test pulses down each individual wire, lighting up LED lights on the receiver box. Most testers will
show you a result of the pass. Why do you want to test cables? Even if they are slightly damaged,
network cables will work, but cause packet loss and data corruption to your hardware.
RJ45 Connectors - Ensure your RJ45 connectors are designed for the type of cable you are using
(solid/stranded), as they have different types of teeth for piercing between multiple strands or around a
solid single strand. Note: if you ask in an electrical trades store for RJ45 connectors, you may be asked
whether you want "solid", "stranded" or "flat". The "flat" choice relates to the old flat "silver satin"
cables used in 10Base-T, and should not be used in new Ethernet deployments.
Bulk Cable - Bulk cable can be found at computer stores, electrical stores, and home centers. You can
obtain Category 5, Category 5e, and Category 6 cable, depending on your needs. For lengths shorter
than 50' use a stranded/braided cable. For lengths greater than 50' use a solid cable.
o


There are two types of wire (solid or stranded) and which one you choose should be based on
where and how the patch cable is to be used. See warning above about PLENUM cable.
Stranded wire is best for a workstation patch as it can tolerate flexing without cracking the
conductors; however, the trade off is that they're more susceptible to moisture penetration.[2]
Solid is best used in a wire closet or for a patch that will be moved very infrequently, as the
conductor tends to crack if bent and/or flexed. Cracked conductor leads to "reflections" which
make for chatter on the LAN connection, hampering speed and reliability.
Boots (optional but preferred). It saves the cable in the long run and improves the looks. A boot is a
molded piece of plastic that protects the connector from snagging, if it is pulled through the wall or
conduit. It also provides strain relief on the cable, making it harder for the connector to be pulled off.
Straight edge wire cutter. You may find serrated snips work very nicely. Use something that gives an
easy square cut; avoid diagonal pliers for this reason. You will find that many quality crimpers have a
straight edge cutter built in.

Fish Tape - Fish tape is either a metal or plastic spool of guide wire. Strong enough not to buckle and
bend while being pushed around, but flexible enough to be pushed past corners and bends, fish tape is a
vital tool for some cable runs. Recommended conditions include: conduit, within walls, along structural
beams and girders, in ducting, plenums, and dropped ceilings, or any situation where it's not physically
possible to drag the cable along with you.
How to wire Ethernet Cables
How to wire your own ethernet cables and connectors.
What You Need:
Required:




Ethernet Cable - bulk Category (Cat) 5, 5e, 6, 6a or higher ethernet cable
Wire Cutters - to cut and strip the ethernet cable if necessary
For Patch Cables:
o RJ45 Plugs
o RJ45 Crimper
For Fixed Wiring:
o RJ45 Jacks
o 110 Punch Down Tool
Recommended:


Wire Stripper
Cable Tester
About the Cable:
You can find bulk supplies of ethernet cable at many computer stores or most electrical or home centers. You
want UTP (Unshielded Twisted Pair) ethernet cable of at least Category 5 (Cat 5). Cat 5 is required for basic
10/100 functionality, you will want Cat 5e for gigabit (1000BaseT) operation and Cat 6 or higher gives you a
measure of future proofing. You can also use STP (Shielded Twisted Pair) for extra resistance to external
interference but I won't cover shielded connectors. Bulk ethernet cable comes in many types, there are 2 basic
categories, solid and braided cable. Braided ethernet cable tends to work better in patch applications for desktop
use. It is more flexible and resilient than solid ethernet cable and easier to work with, but really meant for
shorter lengths. Solid ethernet cable is meant for longer runs in a fixed position. Plenum rated ethernet cable
must be used whenever the cable travels through an air circulation space. For example, above a false ceiling or
below a raised floor. It may be difficult or impossible to tell from the package or labelling what type of ethernet
cable it is, so peal out an end and investigate.
Here is what the internals of the ethernet cable look like:
Internal Cable Structure and Color Coding
Inside the ethernet cable, there are 8 color coded wires. These wires are twisted into 4 pairs of wires, each pair
has a common color theme. One wire in the pair being a solid or primarily solid colored wire and the other
being a primarily white wire with a colored stripe (Sometimes ethernet cables won't have any color on the
striped wire, the only way to tell which is which is to check which wire it is twisted around). Examples of the
naming schemes used are: Orange (alternatively Orange/White) for the solid colored wire and White/Orange for
the striped cable. The twists are extremely important. They are there to counteract noise and interference. It is
important to wire according to a standard to get proper performance from the ethernet cable. The TIA/EIA-568-
A specifies two wiring standards for an 8-position modular connector such as RJ45. The two wiring standards,
T568A and T568B vary only in the arrangement of the colored pairs. Tom writes to say "...sources suggest
using T568A cabling since T568B is the AT&T standard, but the US Government specifies T568A since it
matches USOC cabling for pairs 1 & 2, which allows it to work for 1/2 line phones...". Your choice might be
determined by the need to match existing wiring, jacks or personal preference, but you should maintain
consistency. I've shown both below for straight through cabling and just T568B for crossover cabling.
About RJ45 Plugs and Jacks:
The RJ45 plug is an 8-position modular connector that looks like a large phone plug. There are a couple
variations available. The primary variation you need to pay attention to is whether the connector is intended for
braided or solid wire. For braided/stranded wires, the connector has sharp pointed contacts that actually pierce
the wire. For solid wires, the connector has fingers which cut through the insulation and make contact with the
wire by grasping it from both sides. The connector is the weak point in an ethernet cable, choosing the wrong
one will often cause grief later. If you just walk into a computer store, it's nearly impossible to tell what type of
plug it is. You may be able to determine what type it is by crimping one without a cable.
RJ45 jacks come in a variety styles intended for several different mounting options. The choice is one of
requirements and preference. RJ45 jacks are designed to work only with solid ethernet cable. Most jacks come
labeled with color coded wiring diagrams for either T568A, T568B or both. Make sure you end up with the
correct one.
Here is a wiring diagram and pin out:
RJ45 Plug and Jack Pin Out
Ethernet Cable Pin Outs:
There are two basic ethernet cable pin outs. A straight through ethernet cable, which is used to connect to a hub
or switch, and a crossover ethernet cable used to operate in a peer-to-peer fashion without a hub/switch.
Generally all fixed wiring should be run as straight through. Some ethernet interfaces can cross and un-cross a
cable automatically as needed, a handy feature.
Standard, Straight-Through Wiring Diagram(both ends are the same):
Wire Color Wire Diagram 10Base-T Signal
1000Base-T Signal
(T568A)
(T568A)
100Base-TX Signal
1
White/Green
Transmit+
BI_DA+
2
Green
TransmitBI_DA3
White/Orange
Receive+
BI_DB+
4
Blue
Unused
BI_DC+
5
White/Blue
Unused
BI_DC6
Orange
ReceiveBI_DB7
White/Brown
Unused
BI_DD+
8
Brown
Unused
BI_DDStraight-Through Ethernet Cable Pin Out for T568A
Wire Color Wire Diagram 10Base-T Signal
RJ45 Pin #
1000Base-T Signal
(T568B)
(T568B)
100Base-TX Signal
1
White/Orange
Transmit+
BI_DA+
RJ45 Pin #
Wire Color Wire Diagram 10Base-T Signal
1000Base-T Signal
(T568B)
(T568B)
100Base-TX Signal
2
Orange
TransmitBI_DA3
White/Green
Receive+
BI_DB+
4
Blue
Unused
BI_DC+
5
White/Blue
Unused
BI_DC6
Green
ReceiveBI_DB7
White/Brown
Unused
BI_DD+
8
Brown
Unused
BI_DDStraight-Through Ethernet Cable Pin Out for T568B
RJ45 Pin #
Crossover Cable Wiring Diagram(T568B):
RJ45 Pin # (END 1) Wire Color Diagram End #1 RJ45 Pin # (END 2) Wire Color Diagram End #2
1
White/Orange
1
White/Green
2
Orange
2
Green
3
White/Green
3
White/Orange
4
Blue
4
White/Brown
5
White/Blue
5
Brown
6
Green
6
Orange
7
White/Brown
7
Blue
8
Brown
8
White/Blue
Crossover Ethernet Cable Pin Outs
+Note: The crossover ethernet cable layout is suitable for 1000Base-T operation, all 4 pairs are crossed.
How to wire Ethernet Patch Cables:
1. Strip off about 2 inches of the ethernet cable sheath.
2. Untwist the pairs - don't untwist them beyond what you have exposed, the more untwisted cable you
have the worse the problems you can run into.
3. Align the colored wires according to the wiring diagrams above.
4. Trim all the wires to the same length, about 1/2" to 3/4" left exposed from the sheath.
5. Insert the wires into the RJ45 plug - make sure each wire is fully inserted to the front of the RJ45 plug
and in the correct order. The sheath of the ethernet cable should extend into the RJ45 plug by about 1/2"
and will be held in place by the crimp.
6. Crimp the RJ45 plug with the crimper tool.
7. Verify the wires ended up the right order and that the wires extend to the front of the RJ45 plug and
make good contact with the metal contacts in the RJ45 plug
8. Cut the ethernet cable to length - make sure it is more than long enough for your needs.
9. Repeat the above steps for the second RJ45 plug.
How to wire fixed Ethernet Cables:
1.
2.
3.
4.
5.
6.
Run the full length of ethernet cable in place, from endpoint to endpoint, making sure to leave excess.
At one end, cut the wire to length leaving enough length to work, but not too much excess.
Strip off about 2 inches of the ethernet cable sheath.
Align each of the colored wires according to the layout of the jack.
Use the punch down tool to insert each wire into the jack.
Repeat the above steps for the second RJ45 jack.
If an ethernet cable tester is available, use it to verify the proper connectivity of the cable. That should be it, if
your ethernet cable doesn't turn out, look closely at each end and see if you can find the problem. Often a wire
ended up in the wrong place or one of the wires is making no contact or poor contact. Also double check the
color coding to verify it is correct. If you see a mistake or problem, cut the end off and start again. A ethernet
cable tester is invaluable at identifying and highlighting these issues.
When sizing ethernet cables remember that an end to end connection should not extend more than 100m
(~328ft). Try to minimize the ethernet cable length, the longer the cable becomes, the more it may affect
performance. This is usually noticeable as a gradual decrease in speed and increase in latency.
Notes:
Power over Ethernet (PoE):
Power over Ethernet has been implemented in many variations before IEEE standardized 802.3af. 802.3af
specifies the ability to supply an endpoint with 48V DC at up 350mA or 16.8W. The endpoint must be capable
of receiving power on either the data pairs [Mode A] (often called phantom power) or the unused pairs [Mode
B] in 100Base-TX. PoE can be used with any ethernet configuration, including 10Base-T, 100Base-TX and
1000Base-T. Power is only supplied when a valid PoE endpoint is detected by using a low voltage probe to
look for the PoE signature on the endpoint. PoE power is typically supplied in one of two ways, either the host
ethernet switch provides the power, or a "midspan" device is plugged in between the switch and endpoints and
supplies the power. No special cabling is required.
Wire Color Wire Diagram 10Base-T Signal
RJ45 Pin #
PoE
(T568A)
(T568A)
100Base-TX Signal
1
White/Green
Transmit+
Mode A +
2
Green
TransmitMode A +
3
White/Orange
Receive+
Mode A 4
Blue
Unused
Mode B +
5
White/Blue
Unused
Mode B +
6
Orange
ReceiveMode A 7
White/Brown
Unused
Mode B 8
Brown
Unused
Mode B Power over Ethernet Power Delivery
Protocol Details:
Symbol
Encoding
10BaseT
Symbol
Rate
Data Encoding
(Mbaud)
10
None
Data Bits
Minimum
Pairs per Pairs
per
Cable
Channel Used
Symbol
Category
1
1
2
3
Manchester
Multi-level,
100BaseT4
25
8B6T
8/6
3
4
3
2T/Hz
100BaseTX MLT-3
125
4B5B
4/5
1
2
5
PAM5x5
100BaseT2
25
None
2
2
2
3
(2D-PAM5)
1000BaseT 4D-PAM5
125
None
2
4
4
5 (5e)*
DSQ128 (2DLDPC(1723,2048),
10GBase-T
800
3.125
4
4
5e (6a)**
PAM16)
64B/65B, CRC8
*Designed to work on MOST Cat 5 ethernet cable, Cat 5e specifications ensure 1000Base-T operation
**Reduced range when used with Cat 5e and Cat 6, Cat 6a gives the full 100m range
Cable Category Details:
Cable Category Rated Frequency Bandwidth (MHz)
Common Uses
Cable Category Rated Frequency Bandwidth (MHz)
Common Uses
1
None
Telephone Wiring
2
1
Telephone Wiring
3
16
Telephone Wiring, 10Base-T
4
20
Token-Ring, 10Base-T
5
100
100Base-TX, 10Base-T
5e
100
1000Base-T, 100Base-TX
6
250
1000Base-T, 100Base-TX
6a
500
10GBase-T
7
600
10GBase-T
7a
1000
Increasing category levels are backward compatible.
Manufacturers will often test and certify their ethernet cable well beyond the standards.
Related Reading Material









Get IEEE 802 - Ethernet Standards
Charles Spurgeon's Ethernet Website
Network Connection Speeds Reference
Fiber Optic Connector Reference
Ethernet: The Definitive Guide
Interconnections: Bridges, Routers, Switches, and Internetworking Protocols
The Switch Book: The Complete Guide to LAN Switching Technology
TCP/IP Illustrated 3 Volume Set
o The Protocols (TCP/IP Illustrated, Volume 1)
o The Implementation (TCP/IP Illustrated, Volume 2)
o TCP for Transactions, HTTP, NNTP, and the UNIX(R) Domain Protocols (TCP/IP Illustrated,
Volume 3)
UNIX Network Programming
o Unix Network Programming, Vol. 1: The Sockets Networking API, Third Edition
o UNIX Network Programming, Volume 2: Interprocess Communications (2nd Edition)
Power over Ethernet
From Wikipedia, the free encyclopedia
Wireless LAN access point, powered by a PoE splitter
Power over Ethernet or PoE technology describes a system to pass electrical power safely, along with data, on
Ethernet cabling. PoE requires category 5 cable or higher for high power levels, but can operate with category 3
cable for low power levels.[1] Power can come from a power supply within a PoE-enabled networking device
such as an Ethernet switch or can be injected into a cable run with a midspan power supply.
The IEEE 802.3af-2003[2] PoE standard provides up to 15.4 W of DC power (minimum 44 V DC and
350 mA[3][4]) to each device.[5] Only 12.95 W is assured to be available at the powered device as some power is
dissipated in the cable.[6]
The IEEE 802.3at-2009[7] PoE standard, also known as PoE+ or PoE plus, provides up to 25.5 W of power.[8]
Some vendors have announced products that claim to comply with the 802.3at standard and offer up to 51 W of
power over a single cable by utilizing all four pairs in the Cat.5 cable.[9] Numerous non-standard schemes had
been used prior to PoE standardization to provide power over Ethernet cabling. Some are still in active use.
Advantages over other integrated data and power standards
This technology is especially useful for powering IP telephones, wireless LAN access points, cameras with pan
tilt and zoom (PTZ), remote Ethernet switches, embedded computers, thin clients and LCDs.
All these require more power than USB offers and very often must be powered over longer runs of cable than
USB permits. In addition, PoE uses only one type of connector, an 8P8C modular connector, whereas there are
numerous types of USB connectors.
PoE is presently deployed in applications where USB is unsuitable and where AC power would be
inconvenient, expensive[note 1] or infeasible to supply. However, even where USB or AC power could be used,
PoE has several advantages over either, including the following:





Cheaper cabling — even category 5 cable is cheaper than USB repeaters, and the task of meeting
building code requirements to run AC power cable is eliminated.
A Gigabit of data per second to every device is possible, which exceeds 2009 USB and the AC
powerline networking capabilities.
Global organizations can deploy PoE everywhere without concern for any local variance in AC power
standards, outlets, plugs, or reliability.
Direct injection from standard 48 V DC battery power arrays; this enables critical infrastructure to run
more easily in outages, and make power rationing decisions centrally for all the PoE devices.
Symmetric distribution is possible. Unlike USB and AC outlets, power can be supplied at either end of
the cable or outlet. This means the location of the power source can be determined after cables and
outlets are installed.
Uses for PoE
PoE 1140E VoIP Phone
Uses for Power over Ethernet include:







Network routers
A mini network switch installed in distant rooms, to support a small cluster of ports from one uplink
cable. (These ports on the mini-switch do not themselves provide PoE.)
Network webcams
Network Intercom / Paging / Public address systems and hallway speaker amplifiers
VoIP phones
Wall clocks in rooms and hallways, with time set using Network Time Protocol
Wireless access points
Terminology
Power sourcing equipment
Power sourcing equipment (PSE) is a device (switch or hub for instance) that will provide power in a PoE
setup. Maximum allowed continuous output power per such device in IEEE 802.3af is 15.40 W.
When the device is a switch, it's called an endspan. Otherwise, if it's an intermediary device between a non PoE
capable switch and a PoE device, it's called a midspan.
Powered device
A powered device (PD) is a device powered by a PSE and thus consumes energy. Examples include wireless
access points, IP Phones, and IP cameras. The IEEE 802.3af standard specifies a minimum available power of
12.95 W.
Many powered devices have another connector for an optional auxiliary power supply. If used, this gives
backup power to the device if the power to the Ethernet connector is inadequate or suddenly fails.[10]
Power management features and integration
Avaya ERS-5520 switch with 48 Power over Ethernet ports
Most advocates expect PoE to become a global longterm DC power cabling standard and replace "wall wart"
converters, which cannot be easily centrally managed, waste energy, are often poorly designed, and are easily
vulnerable to damage from surges and brownouts. A combination of G.9960 networking on existing AC power
lines to an outlet where a PoE router is plugged in is capable of moving a gigabit per second to every device,
with minimal wiring and participating fully in both AC and DC device power demand management.
Integration with the IEEE 802.3az standard, the energy management capabilities of the combined standard are
expected to be formidable. However, that integration has not yet occurred.
There are several PoE implementations, including ad-hoc techniques, but using the IEEE standard for supplying
power over Ethernet is strongly recommended.[11]
Standard implementation
Standards-based power over Ethernet is implemented following the specifications in IEEE 802.3af-2003 (which
was later incorporated as clause 33 into IEEE 802.3-2005) or the 2009 update, IEEE 802.3at. A phantom power
technique is used to allow the powered pairs to also carry data. This permits its use not only with 10BASE-T
and 100BASE-TX, which use only two of the four pairs in the cable, but also with 1000BASE-T (gigabit
Ethernet), which uses all four pairs for data transmission. This is possible because all versions of Ethernet over
twisted pair cable specify differential data transmission over each pair with transformer coupling; the DC
supply and load connections can be made to the transformer center-taps at each end. Each pair thus operates in
common mode as one side of the DC supply, so two pairs are required to complete the circuit. The polarity of
the DC supply may be inverted by crossover cables; the powered device must operate with either pair: spare
pairs 4-5 and 7-8 or data pairs 1-2 and 3-6. Polarity is required on data pairs, and ambiguously implemented for
spare pairs, with the use of a diode bridge.
Property
Power available at PD[note 2]
Maximum power delivered by
PSE
Voltage range (at PSE)
Voltage range (at PD)
Maximum current
Power management
De rating of maximum cable
ambient operating temperature
Supported cabling
Supported modes
Standard PoE parameters and comparison
802.3af (802.3at Type 1)
12.95 W
25.50 W
15.40 W
802.3at Type 2
34.20 W
44.0 - 57.0 V[12]
37.0 - 57.0 V[13]
350 mA[14]
Three power class levels
negotiated at initial
connection
50.0 - 57.0 V[12]
42.5 - 57.0 V[13]
600 mA[14]
Four power class levels negotiated at initial
connection or 0.1 W steps negotiated
continuously
5°C with two pairs used, 10°C with four pairs
None
used
[1]
Category 3 and Category 5 Category 5[1][note 3]
Mode A (endspan), Mode B Mode A, Mode B, Mode A and Mode B
(midspan)
operating simultaneously
Powering devices
Two modes, A and B, are available.
Mode A has two alternate configurations (MDI and MDI-X), using the same pairs but with different polarities.
In mode A, pins 1 and 2 (pair #2 in T568B wiring) form one side of the 48 V DC, and pins 3 and 6 (pair #3 in
T568B) form the other side. These are the same two pairs used for data transmission in 10BASE-T and
100BASE-TX, allowing the provision of both power and data over only two pairs in such networks. The free
polarity allows PoE to accommodate for crossover cables, patch cables and auto-MDIX.
In mode B, pins 4-5 (pair #1 in both T568A and T568B) form one side of the DC supply and pins 7-8 (pair #4
in both T568A and T568B) provide the return; these are the "spare" pairs in 10BASE-T and 100BASE-TX.
Mode B, therefore, requires a 4-pair cable.
The PSE, not the powered device (PD), decides whether power mode A or B shall be used. PDs that implement
only Mode A or Mode B are disallowed by the standard.
The PSE can implement mode A or B or both. A PD indicates that it is standards-compliant by placing a 25 kΩ
resistor between the powered pairs. A major difference between IEEE802.3af and IEEE802.3at is that while
IEEE802.3af clearly precluded collocating two PD interfaces on a single RJ45 connector, IEEE802.3at changes
the definition of a PD, and therefore allows two PDs collocation, one mode A and the other mode B. If the PSE
detects a resistance that is too high or too low (including a short circuit), no power is applied. This protects
devices that do not support PoE. An optional "power class" feature allows the PD to indicate its power
requirements by changing the sense resistance at higher voltages. To stay powered, the PD must continuously
use 5–10 mA for at least 60 ms with no less than 400 ms since last use or else it will be unpowered by the
PSE.[15]
There are two types of PSEs: endspans and midspans. Endspans are Ethernet switches that include the power
over Ethernet transmission circuitry. Endspans are commonly called PoE switches. Midspans are power
injectors that stand between a regular Ethernet switch and the powered device, injecting power without
affecting the data.
Endspans are normally used on new installations or when the switch has to be replaced for other reasons (such
as moving from 10/100 Mbit/s to 1 Gbit/s or adding security protocols), which makes it convenient to add the
PoE capability. Midspans are used when there is no desire to replace and configure a new Ethernet switch, and
only PoE needs to be added to the network.
Stages of powering up a PoE link
Volts specified
[V]
Stage
Action
802.3af 802.3at
Detection
PSE detects if the PD has the correct signature resistance of 15 - 33 kΩ
2.7 - 10.0
Classification
PSE detects resistor indicating power range (see below)
14.5 - 20.5
Mark 1
Signals PSE is 802.3at capable. PD presents a 0.25 - 4 mA load.
7 - 10
Class 2
PSE output classification voltage again to indicate 802.3at capability 14.5 - 20.5
Mark 2
Signals PSE is 802.3at capable. PD presents a 0.25 - 4 mA load.
7 - 10
Startup
Startup voltage
> 42
> 37.2[16]
Normal operation Supply power to device
44 - 57 50 - 57[16]
IEEE 802.3at capable devices are also referred to as "type 2". An 802.3at PSE may also use layer2
communication to signal 802.3at capability.[16]
Power levels available[17]
Classification current Power range
Class Usage
Class description
[mA]
[Watt]
0
Default 0 - 4
0.44 - 12.94 Classification unimplemented
1
Optional 9 - 12
0.44 - 3.84 Very Low power
2
Optional 17 - 20
3.84 - 6.49 Low power
3
Optional 26 - 30
6.49 - 12.95 Mid power
4
Reserved 36 - 44
12.95 - 25.50 High power
PSEs classify as Class 0[17]
For IEEE 802.3at (type 2) devices class 4 instead of Reserved has a power range of 12.95 - 25.5 W.[16]
Configuration via Ethernet layer 2 LLDP
TLV Header
LLDP-MED Advanced Power Management[18]
MED Header
Extended power via MDI
TIA
Type
Length OUI
(7
(9 bits)
(3
bits)
octets)
127
7
Extended power via
MDI subtype
(1 octet)
Power
type
(2 bits)
Power source
(2 bits)
Power
priority
(4 bits)
Power value
(2 octets)
4
PSE or
PD
Normal or Backup
conservation
Critical,
High,
Low
0 - 102.3 W in
0.1 W steps
00-12BB
The setup phases are as follows:



PSE (provider) tests PD (consumer) physically using 802.3af phase class 3.
o PSE powers up PD.
PD sends to PSE: I'm a PD, max power = X, max power requested = X.
PSE sends to PD: I'm a PSE , max power allowed = X.
o PD may now use the amount of power as specified by the PSE.
The rules for this power negotiation are:





PD shall never request more power than physical 802.3af class
PD shall never draw more than max power advertised by PSE
PSE may deny any PD drawing more power than max allowed by PSE
PSE shall not reduce power allocated to PD, that is in use
PSE may request reduced power, via conservation mode
Non-standard implementations
Cisco
Cisco manufactured WLAN access points and IP phones many years before there was an IEEE standard for
delivering PoE. Cisco's original PoE implementation is not software upgradeable to the IEEE 802.3af standard.
Cisco's original PoE equipment was capable of delivering up to 10 W per port. The amount of power to be
delivered is negotiated between the endpoint and the Cisco switch based on a power value that was added to the
Cisco proprietary Cisco Discovery Protocol (CDP). CDP is also responsible for dynamically communicating
the Voice VLAN value from the Cisco switch to the Cisco IP Phone.
Under Cisco's pre-standard scheme, the PSE (switch) will send a Fast Link Pulse (FLP) on the transmit pair.
The PD (device) connects the transmit line to the receive line via a low pass filter. And thus the PSE gets the
FLP in return. And a common mode current between pair 1 and 2 will be provided resulting in 48 V DC[19] and
6.3 W[20] default of allocated power. The PD has then to provide Ethernet link within 5 seconds to the autonegotiation mode switch port. A later CDP message with a type-length-value tells the PSE its final power
requirement. A discontinued link pulses shuts down power.[21]
PowerDsine
PowerDsine, now a Microsemi brand, sold midspans since 1999 with its proprietary Power over LAN solution.
Several companies like Level1 , 3Com and Nortel followed PowerDsine's Power over LAN.
Notes
1. ^ Mains wiring must often be done by qualified and/or licensed electricians for legal or insurance
reasons.
2. ^ Most switched power supplies within the powered device will lose another 10 to 25% of the available
power.
3. ^ More stringent cable specification allows assumption of more current carrying capacity and lower
resistance (20.0 Ohms for Category 3 versus 12.5 Ohms for Category 5).
Category 5 cable uses 24 AWG conductors, which can safely carry 360 mA at 50 V according to the latest TIA
rulingThe cable has eight conductors (only half of which are used for power) and therefore the absolute
maximum power transmitted using direct current is 50 V × 0.360 A × 2 = 36 W. Considering the voltage drop
after 100 m, a PD would be able to receive 31.6 W. The additional heat generated in the wires by PoE at this
current level (4.4 watts per 100 meter cable) limits the total number of cables in a bundle to be 100 cables at
45 °C, according to the TIA.
Drawbacks of IEEE 802.3af are:




Excessive voltage with a peak at 60 V (many standard components are limited to ~30 V).
Undefined polarity (requires a diode bridge which causes a voltage drop and require more board space
and components).
Undefined wire pairs (multiple configurations must be handled which requires more board space and
components) (The diode bridge will waste 0.74 W at 25.5 W operation)
Unexpected AC current flow due to faulty design of the POE source, and/or power supplied to nondifferential I/O signals such as RS232. The major cause of this problem is unaccounted for capacitance
which can form a bridge to an AC wall source. Symptoms include electrical shock when touching the
case, and failure to negotiate startup on some POE sources, especially when non-differential I/O is
connected prior to power up.
A partial solution to the input source drawbacks of IEEE 802.3af is to assume pin 4 + 5 as positive (+) and pin
7 + 8 as negative (-). This would not be standards compliant but will make PD implementation easier and not
damage anything. Any incompatibilities with IEEE 802.3af will only result in an unpowered device.
Another solution is to use an existing IEEE 802.3af compliant power supply chip, adapting its sample designs
to your specific needs. The chip will handle negotiation, slow startup, multiple auxiliary sources, and possibly
provide additional protection in the form of automatic shutdown. If possible use the fully isolated design,
especially if there is exposed metal on the outer case. The drawback can be a high component count.
POE compatible RJ45 connectors are available with internal magnetics, input diodes, minor capacitors, and
LED indicators incorporated into the package. These can help reduce component count. Be careful when
placing them anywhere but at the edge of a circuit board, as most are designed to support a dangling cable. If
the cable has a boot protecting the end, it can press against the circuit board and produce an intermittent
connection.
The 0.74 W waste in the diode bridge, above, assumes the use of standard rectifier diodes. If Schottky diodes
are used, the waste will be half that much. In either case, the waste is much less than the losses in the DC-DC
converter that must be used to convert the power to the low voltages used in the PD logic circuits.
PINS on
Switch
Pin 1
Pin 2
Pin 3
Pin 4
Pin 5
Pin 6
Pin 7
Pin 8
802.3af Standards A and B
10/100 DC on Spares
10/100 Mixed DC & Data
(mode B)
(mode A)
Rx +
Rx +
DC +
Rx Rx DC +
Tx +
Tx +
DC DC +
unused
DC +
unused
Tx Tx DC DC unused
DC unused
1000 (1 Gigabit) DC & BiData
TxRx A +
DC +
TxRx A DC +
TxRx B +
DC TxRx C +
TxRx C TxRx B DC TxRx D +
TxRx D -
Another modification is to limit voltage from the PSE to 30 V and thus enable the use of standard components.
But this may destroy the PD if it is connected to a PSE that isn't modified to keep the voltage low enough. It
also limits the amount of power that can be used.
When converting an existing ethernet design to accept POE, verify that the input isolation transformer is rated
to carry POE currents.
See also







Network switch, connects network nodes with independent pipes (efficient).
Category 5 cable
Power line communication, data communication over mains electricity.
Switched-mode power supply, efficient electrical power conversion.
ITU-T G.hn, a standard that provides a way to create a high-speed (up to 1 Gigabit/s) Local area
network using existing home wiring (power lines, phone lines and coaxial cables).
Phantom power, long established standard technique to power microphones.
HomePlug Powerline Alliance, an industry trade group on datacommunication over mains electricity.
References
^ a b c IEEE 802.3at-2009, clause 33.1.1c
^ 802.3af-2003, June 2003
^ IEEE 802.3-2005, section 2, table 33-5, item 1
^ IEEE 802.3-2005, section 2, table 33-5, item 4
^ IEEE 802.3-2005, section 2, table 33-5, item 14
^ IEEE 802.3-2005, section 2, clause 33.3.5.2
^ 802.3at Amendment 3: Data Terminal Equipment (DTE) Power via the Media Dependent Interface
(MDI) Enhancements, September 11, 2009
8. ^ "Amendment to IEEE 802.3 Standard Enhances Power Management and Increases Available Power".
IEEE. http://standards.ieee.org/announcements/stdbd_approves_ieee802.3at.html. Retrieved 2010-0624.
9. ^ "802.3at-2009 Power over Ethernet (PoE) Plus Standard Ratified". http://blog.tmcnet.com/blog/tomkeating/voip/8023at-2009-power-over-ethernet-poe-plus-standard-ratified.asp. Retrieved 2010-06-24.
10. ^ National Semiconductor application note 1474: "The LM507X Family of PoE Devices: Frequently
Asked Questions (FAQs)"
11. ^ [1]
12. ^ a b IEEE 802.3at-2009 Table 33-11
13. ^ a b IEEE 802.3at-2009 Table 33-18
14. ^ a b IEEE 802.3at-2009 Table 33-1
15. ^ Banish Those "Wall Warts" With Power Over Ethernet
16. ^ a b c d "LTC4278 IEEE 802.3at PD with Synchronous No-Opto Flyback Controller and 12V Aux
Support". http://cds.linear.com/docs/Datasheet/4278fa.pdf. 2010-01-11 cds.linear.com
17. ^ a b IEEE 802.3-2005, section 2, table 33-3
18. ^ a b "LLDP / LLDP-MED Proposal for PoE Plus (2006-09-15)".
http://www.ieee802.org/1/files/public/docs2006/ab-congdon-lldp-med-8023at-0906.pdf.2010-01-10
19. ^ "Planning for Cisco IP Telephony > Network Infrastructure Analysis".
http://www.ciscopress.com/articles/article.asp?p=385336&seqNum=2&rll=1. 2010-01-12
ciscopress.com
20. ^ "Power over Ethernet on the Cisco Catalyst 6500 Series Switch".
http://www.conticomp.com/PDF/CAT6500POE_ds.pdf. 2010-01-12 conticomp.com
21. ^ "Understanding the Cisco IP Phone 10/100 Ethernet In-Line Power Detection Algorithm - Cisco
Systems".
http://www.cisco.com/en/US/products/hw/phones/ps379/products_tech_note09186a00801189b5.shtml.
2010-01-12 cisco.com
1.
2.
3.
4.
5.
6.
7.
External links


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ieee802.org: Download the IEEE 802.3 standards
ieee802.org: IEEE 802.3af Task Force
ieee802.org: IEEE 802.3at Task Force
www.altair.org Power Over Ethernet
PoE portal