Multitech RF500S Uživatelský manuál stáhnout pdf (Strana 19)

6.1.2 10Mbps - 100Mbps - 1Gbps - 10Gbps

Initially UTP Ethernet ran at 10 million bits per second. Fast Ethernet increased speed to 100 million bits

per second over Category 5 wiring. Gigabit Ethernet is 10 time faster then Fast Ethernet, 1,000Mbps. Work

is ongoing to increase speed by another factor of 10 to 10 Gigabits per second. Gigabit Ethernet is mainly

used for corporate backbone networks but as costs fall it will be deployed all the way to the desktop.

6.1.3 UTP Unshielded Twisted Pair

A significant cost cabling, regardless of the type of network. Wiring has a relatively long life time, 5-10

years in an office building. This means that several generations of computers use the same wiring. The

Telecommunications Industry Association set about developing a wiring scheme that was independent of

LAN technology. They created five categories based on the maximum frequency the wiring needed to

carry. Only two are in widespread use Cat 3 and 5e. Category 3 is typically used for phone wiring and

Category 5e for 100Mbps Ethernet. Category 5e is a minor enhancement of Category 5. Gigabit Ethernet

was designed to operate over Cat5 copper or fiber optic cable. As Gigabit Ethernet was deployed it was

discovered that not all Cat5 installation were up to the task. This resulted in the Cat5e specification. It

tightened critical parameters. It is the preferred method of wiring today. There is very little cost difference

between Cat3 and Cat5e, most of the cost is pulling, and terminating the wires. It is false economy to limit

the installation to only 10Mbp/s.

6.1.4 Structured Wiring

EIA/TIA 568 Category 5e unshielded twisted pair is the preferred standard LANs. Phone wiring typically

uses Category 3 because the wire and connectors are a little cheaper. The FCC recently changed rules to

require phone wiring to use Cat 3 as a minimum and be run home run fashion like other structured wiring.

In “Home Run” wiring each outlet is connect to a separate cable and the cable is run directly back to a

wiring closet Splicing or daisy chaining is no allowed.

UTP is designed for a maximum of 100meters of

length, this includes a patch cord from the computer to

the wall jack, 90 meters of wiring (in TIA parlance

call horizontal wiring), and another patch cord in the

wiring closet to connect facility wiring to the hub.

Horizontal wiring is terminated to terminal blocks in

the wiring closet. 66 style blocks can be used however

110 style blocks are more common because they are

denser, allowing more terminations for a given

amount of wall space. The picture shows typical 110

blocks. Network installations use 110 blocks

preassembled to modular jacks. The inside wire is

terminated to the 110 block on the back of the jack

panel. The front of the panel consist of a series of

modular jacks. Patch cords connect the terminal block to the hub.

Terminating horizontal wiring at a punchdown block and then connecting selected outlets to the hub with a

patch cord makes for a very flexible installation. This is ideal when used with a large number of outlets that

are constantly being rearranged. In a small office or home the situation is different, the number of outlets is

small and one can purchase a low cost hub with enough ports for all outlets. In a home installation wiring

can be terminated directly to UTP plugs in the wiring closet. Plugs are somewhat more difficult install then

receptacles so it is not for the faint of heart but doing so eliminates the cost and space of the 110 blocks,

and patch cable. The horizontal wiring is terminated with a UTP plug and connected directly to the hub.

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