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The gigabit ethernet stand it requires that all pins be connected.

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So this is an example of a crossover cable for gigabit using the T 5 6 8 beast and notice all pins are

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configured in a crossover fashion.

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All four pairs of wires are used in this example.

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Now in the past you'd have to know when to use a straight through or crossover cable.

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Any of these implementations would use a straight through cable so routed to switch PC to switch PC

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to bridge or PC to hub any of these implementations would use a crossover cable so Roddick to router

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switch to switch PCG PC or hub to hub or bridge to switch.

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PC to server hub to switch.

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And once again router to router all require crossover cables.

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However today automatic crossover or auto MDX is widely used or to MDX was introduced in 1998 and it

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made the requirement for crossover cables obsolete MDI devices are typically rodders all PCs and DX

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devices are typically switches or hubs.

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So they are medium dependent interface crossover devices.

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And in the past you would need to connect and MDI device such as a PC to switch or hub in the old days

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once again certain ports would have a button to flip the roll from MDX to MDI which would allow you

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to connect a switch to a switch using a straight through cable.

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However today in a lot of cases or to MDI MDX allows for automatic switching once the cable is connected.

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The devices can order detect the cable type.

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So there is no need to worry as much about cable types today straight through cable as an example could

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be used between hubs or between switches.

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So in the past used to have to use a crossover cable between two switches but that's not necessarily

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required today straight through cables could be used and devices would work out which side is MDI and

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which side is MDX.

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However be careful that's not always true when on site you may encounter an older Cisco switch that

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doesn't support or to MDI MDX so you may have to use the correct cabling type between older devices.

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There are various categories of cable in general the higher the category the more twists and the less

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susceptible the cable is to electromagnetic interference the higher the category the more stringent

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the specifications are for crosstalk and system noise higher cable categories typically support higher

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frequencies and higher speeds.

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I wouldn't try to remember all the categories of cable if I were you just see this as an explanation

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of the various categories you main counter in networks or in documentation.

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Category one was previously used for telephones and modems.

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So Category 1 is a grade of unshielded Twista pay cabling designed for telephone communications and

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was at one time the most common on premise wiring.

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This is not suitable for data transmission.

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Category 2 was previously used for telephones and data networks up to four megabits per second.

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Category 3 was used previously for data networks up to 10 megabits per second.

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It's now generally used for telephones.

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Category 4 is defined up to 20 megahertz which speeds up to 16 megabits per second.

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Category 5 is defined up to 100 megahertz speeds of 10 or 100 megabits per second when using toupees

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and one gigabits per second when using four pairs category one two and four are no longer used.

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Category 3 is no longer used in data networks and generally Category 5 is no longer used.

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But there's a lot of installations that have Category 5.

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So you may still come across.

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Cat 5 was an improvement on Cat 5.

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It supports frequencies up to 100 megahertz and support speeds up to 1 gigabits per second.

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It has a maximum distance of 100 metres and is similar to Cat 5 but improved the Cat 5 specification

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by reducing noise and signal interference.

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So some crosstalk was improved with the new spec..

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The Category 5 specification improves upon the Category 5 specification by tightening some crosstalk

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specifications and introducing new cross-talk specifications that were not present in the original category

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5 specification.

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The bandwidth of cat 5 and Cat 5 is the same.

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In other words 100 megahertz and the physical cable construction is the same.

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And the reality is that most Cat 5 cables meet Cat 5 specifications though it may not be tested or certified

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as such category 6 defines frequencies up to 250 megahertz and increases the number of paid Twist's

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per inch to reduce signal noise and interference.

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It supports 10 gigabits per second but only up to 55 meters the top of specifications and cat six guarantee

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100 meter runs at 1 gigabits per second.

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So category six cable commonly referred to as Cat 6 is a standardized cable for gigabit Ethernet and

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is backward compatible with Category 5 or Category 5.

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And Category three cable standards compared to Cat 5 or cat 5 the cat 6 features more stringent specifications

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for cross-talk and system noise.

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The cable standard provides performance up to 250 megahertz and is suitable for 10 base t hundred based

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X for foster net and 1000 based T or gigabit ethernet as well as 10 gigabit ethernet category's 6 a

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or augmented category 6 defined frequencies up to 500 megahertz which is twice that of cat 6.

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It also includes improvements with regards to crosstalk and support speeds up to 10 gigabits per second.

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But in this case with the extended cable length of 100 meters category six maximum cable length was

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fifty five meters in a favorable environment but only 37 meters in an environment where a lot of crosstalk

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took place such as when cables are bundled together.

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So Category 6 A or cat 6 say improved a specification allowing for 10 gigabits per second up to 100

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meters.

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Category 7 or Cat 7 defined frequencies up to 600 megahertz and support speeds of up to 10 gigabits

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per second up to 100 meters.

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The connectors in Cat 7 can be terra connectors rather than 8 8 C or 8 position 8 contact which we commonly

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referred to as an RJ 45 connector.

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So here's an example of a Terra connector and Cat 7.

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Notice the pairs of cable in Cat 7 are protected by a foil shield.

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The twisting of pegs and the number of turns per inch is also increased to protect from CROSSTALK.

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And in addition has a 10 copeck twinax catagory 7 is also known as Clauss if and also has a class if

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a which defined frequencies up to 100 megahertz per second and which in theory support speeds up to

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40 gigabits per second and 100 gigabits per second at 50 meters.

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This is currently an ISO or ISO standard but it is not recognized by the TIAA a for brand new installations.

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It's generally recommended that cat 6 AA or cat 7 be used if reusing existing cat 6 cabling cable segments

86
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must be tested up to 350 megahertz and limited by TIAA a recommendations not category 8 is the next

87
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generation twisted pay cabling specification and is being developed to support 40 gigabits per second.

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In other words four times the speed of 10 gigabit Ethernet.

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The technical recommendation for category 8 was released in March 2013 and has both class 1 and class

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2.

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In other words category 8.1 cable and category agree to 2 cables category 8.1 is fully backward compatible

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and interoperable with Category 6.

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A using RJ 45 connectors category 8 2 is interoperable with catagory 7 cabling using either Arjay 45

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or Tehrik connectors.