Table 2-2 EIA-568-A Wire Pairs and Pins

Pin Number	Wire Pair Number	Wire Colors
		White with green stripe
		Green
		White with orange stripe
		Blue
		White with blue stripe
		Orange
		White with brown stripe
		Brown

 

 

Figure 2-3 illustrates an RJ-45 cable connector and port with the pins shown in Table 2-1 identi-fied.

 

Pin 8

 

Pin 1

 

 

Figure 2-3 An RJ-45 cable (left) and connector (right) are used for Fast and Gigabit Ethernet net-working.

 

A straight-through patch cable directly maps the pins on both ends of the cable. Pin 1 goes to pin 1, pin 2 to pin 2, and so on. These cables are used when connecting different layered devices, a host to a switch, or a switch to a router. A crossover cable maps the sending pin to the expected receiving pin. Pin 1 maps to pin 3, pin 2 to pin 6, and so on. These are used when connecting simi-lar devices, such as a host to a host and a switch to a switch. To create a crossover cable, wire one end to the 568-A standard, and the other end to the 568-B standard.

 

Ethernet STP or UTP cables use the RJ-45 connector shown in Figure 2-3.

Chapter 2: Networking 43

 

Coaxial Network Cables and Connectors

 

10Mbps Ethernet used coaxial cables and connectors. This type of cabling is no longer common in office networks, but it is still used in some types of industrial networks because the cable is well shielded against interference.

 

Coaxial cabling creates a bus topology; each end of the bus must be terminated, and if any part of the bus fails, the entire network fails.

 

10Mbps Ethernet used RG-8 coaxial cable with a vampire tap (Thicknet) or RG-58 with a BNC connector. BNC-based networks use a T-shaped adapter to pass the signal between stations. Figure 2-4 compares network cards that use BNC, RJ-45, and AUI (vampire tap) connections.

 

Resistor cap	AUI connector
(indicates end of network) ^RJ-45 port
	(15-pin)

 

AUI cable

 

BNC connector	Thin Ethernet
on network
cable	RJ-45 cable
adapter
BNC connector
	on T-adapter

 

Figure 2-4 Combo UTP/BNC/AUI Ethernet network cards (left and right) compared with a UTP/STP-only Ethernet network card (center).

 

Two other types of coaxial cable are common in cable Internet, satellite Internet, and fixed wire-less Internet installations. These cables use the F-connector for direct connection between devices

 

RG-59 —Used in older cable TV or satellite TV installations; 75ohm resistance. Also usedby the long-obsolete ARCnet LAN standard.

 

RG-6 —Uses same connectors as RG-59, but has a larger diameter with superior shielding;used in cable TV/Internet, satellite TV/Internet, and fixed wireless Internet/TV service; 75ohm resistance.

44 CompTIA A+ Quick Reference

 

TCP/IP Addressing

 

IP addresses are considered logical because they can be assigned to the network interface card (NIC) by the network administrator. MAC addresses are permanently burned into the NIC and are, therefore, considered physical.