What Kind of Cables Should I Use in TCP/IP Network?

 

A key component in wired  networks is — cables!

Twisted-pair Ethernet cable is the most common type of home network wiring used today (and for the foreseeable future). Twisted-pair Ethernet cables are used to connect:

• DSL/cable routers or modems to computers
• DSL/cable routers or modems to wireless access points
• DSL/cable routers or modems to hubs or switches
• Computers to hubs or switches
• Computers to other computers
• Other devices (such as network printers) to computers, hubs, or switches.

Twisted pairs and RJ-45 connectors

Twisted-pair Ethernet cables consist of eight copper insulated wires in a plastic sleeve. Two wires are twisted together in a pair for a total of four pairs, and then the four pairs are twisted together to form the cable. The twists and pairs affect certain performance characteristics of the cable, such as crosstalk, attenuation, and electromagnetic interference (EMI).

Crosstalk occurs when an electrical signal transmitted over one wire negatively affects the electrical signal transmitted over another wire. Attenuation is the gradual loss of intensity of an electrical signal as it travels over the wire. EMI is noise (unwanted electrical signals) that is generated between the wires by the various electrical signals that are transmitted.

A clear plastic jack, known as an RJ-45 connector, is attached to both ends of the twisted-pair Ethernet cable. An RJ-45 connector looks very similar to a telephone jack (which is known as an RJ-11 connector).

Commonly used Ethernet UTP cable

Categories of twisted-pair cables

There are several categories of twisted-pair cabling, but only three that are commonly used for Ethernet networks and  performance characteristics these are as follows:

• Cat5: Supports speeds up to 100 Mbps at 100 MHz, with a maximum cable length of 328 feet (100 meters).
• Cat 5e: Supports speeds up to 1,000 Mbps (or 1 Gbps) at 100 MHz, with a maximum cable length of 328 feet (100 meters).
• Cat6: Supports speeds up to 1,000 Mbps (or 1 Gbps) at 250 MHz, with a maximum cable length of 295 feet (90 meters).

Unshielded versus shielded cables

Twisted-pair Ethernet cabling can also be unshielded (common) or shielded (not so common). Unshielded twisted-pair (UTP) cabling is used in both large enterprise networks and small home networks. It is relatively inexpensive and much more flexible than shielded twisted-pair (STP) cabling.

STP cabling is more expensive and less pliable than UTP cabling. It is used in industrial environments and other noisy environments that are prone to high electromagnetic interference (EMI). The individual pairs of wires in STP cables are wrapped in foil or other metal shielding, and an outer metal shielding may also cover the entire group of twisted pairs (beneath the outer sleeve).

Straight-through versus crossover cables

In most cases, you will use straight-through twisted-pair Ethernet cables to connect the devices on your network. Crossover cables are sometimes required to directly connect two computers together (if one of them has a network adapter that is more than a few years old), to connect very cheap (or old) network switches that do not have an uplink port, or to connect some types of specialized network devices.

####    END ###