The gigabit ethernet stand it requires that all pins be connected.
So this is an example of a crossover cable for gigabit using the T 5 6 8 beast and notice all pins are
configured in a crossover fashion.
All four pairs of wires are used in this example.
Now in the past you'd have to know when to use a straight through or crossover cable.
Any of these implementations would use a straight through cable so routed to switch PC to switch PC
to bridge or PC to hub any of these implementations would use a crossover cable so Roddick to router
switch to switch PCG PC or hub to hub or bridge to switch.
PC to server hub to switch.
And once again router to router all require crossover cables.
However today automatic crossover or auto MDX is widely used or to MDX was introduced in 1998 and it
made the requirement for crossover cables obsolete MDI devices are typically rodders all PCs and DX
devices are typically switches or hubs.
So they are medium dependent interface crossover devices.
And in the past you would need to connect and MDI device such as a PC to switch or hub in the old days
once again certain ports would have a button to flip the roll from MDX to MDI which would allow you
to connect a switch to a switch using a straight through cable.
However today in a lot of cases or to MDI MDX allows for automatic switching once the cable is connected.
The devices can order detect the cable type.
So there is no need to worry as much about cable types today straight through cable as an example could
be used between hubs or between switches.
So in the past used to have to use a crossover cable between two switches but that's not necessarily
required today straight through cables could be used and devices would work out which side is MDI and
which side is MDX.
However be careful that's not always true when on site you may encounter an older Cisco switch that
doesn't support or to MDI MDX so you may have to use the correct cabling type between older devices.
There are various categories of cable in general the higher the category the more twists and the less
susceptible the cable is to electromagnetic interference the higher the category the more stringent
the specifications are for crosstalk and system noise higher cable categories typically support higher
frequencies and higher speeds.
I wouldn't try to remember all the categories of cable if I were you just see this as an explanation
of the various categories you main counter in networks or in documentation.
Category one was previously used for telephones and modems.
So Category 1 is a grade of unshielded Twista pay cabling designed for telephone communications and
was at one time the most common on premise wiring.
This is not suitable for data transmission.
Category 2 was previously used for telephones and data networks up to four megabits per second.
Category 3 was used previously for data networks up to 10 megabits per second.
It's now generally used for telephones.
Category 4 is defined up to 20 megahertz which speeds up to 16 megabits per second.
Category 5 is defined up to 100 megahertz speeds of 10 or 100 megabits per second when using toupees
and one gigabits per second when using four pairs category one two and four are no longer used.
Category 3 is no longer used in data networks and generally Category 5 is no longer used.
But there's a lot of installations that have Category 5.
So you may still come across.
Cat 5 was an improvement on Cat 5.
It supports frequencies up to 100 megahertz and support speeds up to 1 gigabits per second.
It has a maximum distance of 100 metres and is similar to Cat 5 but improved the Cat 5 specification
by reducing noise and signal interference.
So some crosstalk was improved with the new spec..
The Category 5 specification improves upon the Category 5 specification by tightening some crosstalk
specifications and introducing new cross-talk specifications that were not present in the original category
5 specification.
The bandwidth of cat 5 and Cat 5 is the same.
In other words 100 megahertz and the physical cable construction is the same.
And the reality is that most Cat 5 cables meet Cat 5 specifications though it may not be tested or certified
as such category 6 defines frequencies up to 250 megahertz and increases the number of paid Twist's
per inch to reduce signal noise and interference.
It supports 10 gigabits per second but only up to 55 meters the top of specifications and cat six guarantee
100 meter runs at 1 gigabits per second.
So category six cable commonly referred to as Cat 6 is a standardized cable for gigabit Ethernet and
is backward compatible with Category 5 or Category 5.
And Category three cable standards compared to Cat 5 or cat 5 the cat 6 features more stringent specifications
for cross-talk and system noise.
The cable standard provides performance up to 250 megahertz and is suitable for 10 base t hundred based
X for foster net and 1000 based T or gigabit ethernet as well as 10 gigabit ethernet category's 6 a
or augmented category 6 defined frequencies up to 500 megahertz which is twice that of cat 6.
It also includes improvements with regards to crosstalk and support speeds up to 10 gigabits per second.
But in this case with the extended cable length of 100 meters category six maximum cable length was
fifty five meters in a favorable environment but only 37 meters in an environment where a lot of crosstalk
took place such as when cables are bundled together.
So Category 6 A or cat 6 say improved a specification allowing for 10 gigabits per second up to 100
meters.
Category 7 or Cat 7 defined frequencies up to 600 megahertz and support speeds of up to 10 gigabits
per second up to 100 meters.
The connectors in Cat 7 can be terra connectors rather than 8 8 C or 8 position 8 contact which we commonly
referred to as an RJ 45 connector.
So here's an example of a Terra connector and Cat 7.
Notice the pairs of cable in Cat 7 are protected by a foil shield.
The twisting of pegs and the number of turns per inch is also increased to protect from CROSSTALK.
And in addition has a 10 copeck twinax catagory 7 is also known as Clauss if and also has a class if
a which defined frequencies up to 100 megahertz per second and which in theory support speeds up to
40 gigabits per second and 100 gigabits per second at 50 meters.
This is currently an ISO or ISO standard but it is not recognized by the TIAA a for brand new installations.
It's generally recommended that cat 6 AA or cat 7 be used if reusing existing cat 6 cabling cable segments
must be tested up to 350 megahertz and limited by TIAA a recommendations not category 8 is the next
generation twisted pay cabling specification and is being developed to support 40 gigabits per second.
In other words four times the speed of 10 gigabit Ethernet.
The technical recommendation for category 8 was released in March 2013 and has both class 1 and class
2.
In other words category 8.1 cable and category agree to 2 cables category 8.1 is fully backward compatible
and interoperable with Category 6.
A using RJ 45 connectors category 8 2 is interoperable with catagory 7 cabling using either Arjay 45
or Tehrik connectors.