2.3 Networking Basics Flashcards
Be able to answer the following questions: - What are the two classifications of twisted pair cable? - What are the characteristics of the Cat 5 unshielded twisted pair (UTP) cable type? - How do the Cat 5 and Cat 5e types differ? - What is the general rule for substituting UTP cable types? - What is the purpose of cladding in fiber optic cabling? - What are the advantages of fiber optic cabling? - How do single-mode fiber cables differ from multi-mode? - What connector types are used with f
Internet Service Providers (ISPs)
ISPs are organizations that provide access to the internet as well as providing other internet related services.
Unshielded Twisted Pair (UTP)
UTP is the most commonly used type of Ethernet cable. It consists of two or more twisted pairs of copper wire surrounded by an outer cover.
Fiber Optic
Fiber Optic is a type of cable consisting of glass fibers that transmit data using light.
RJ-45 Connector
RJ-45 is a UTP cable connector typically used in telecommunications or data equipment.
Twisted Pair Cabling Components
- Four pairs of 22- or 24-guage copper wires that carry the data signals. One wire in the pair carries a positive signal; the other carries a negative signal. Wires are twisted into pairs to reduce the effects of electromagnetic interference and crosstalk.
- PVC plastic insulation surrounds each copper wire.
- An outer plastic sheath bundles the wires together and protects them.
- Unshielded twisted pair (UTP) has only an outer plastic sheath. UTP cables are easier to work with and are less expensive than shielded cables.
- Shielded twisted pair (STP) has a grounded outer copper shield around either the entire wire bundle or each wire pair. STP provides additional EMI protection, but costs considerably more than UTP.
TP Cable Categories
CAT 5 | RJ45 | 100 MBPS | 100 MHz | Supports up to 100 Mbps Ethernet
CAT 5e | RJ45 | 1000 Mbps | 100 MHz | Provides better EMI protection than Cat 5, but is similar in other respects. Supports Gigabit Ethernet (gigabit connections require the use of all four twisted pairs).
Cat 6 | RJ45 | 10 Gbps | 250 MHz | Limits 10 Gbps speeds to cable lengths less than 55 meters.
Cat 6a | RJ45 | 10 Gbps | 500 MHz | Provides additional shielding and tighter cable twists than standard Cat 6.
Cat 7 | RJ45 | 10 Gbps | 600 MHz | Has the strictest specifications for crosstalk and noise.
- Each type of UTP cable can be substituted for any category below it, but never for a category above. For example, in a task requiring Cat 5e, Cat 6 can be used as a Cat 5e substitute; however, in a task requiring Cat 6, Cat 5e cannot be used as a substitute for Cat 6.
RJ45 Connector Characteristics
Twisted pair cables use the RJ45 connector to establish network connections. RJ45 connectors:
- Have eight connectors (pins)
- Support up to four pairs of wires
- Use a locking tab to keep the connector secure in an outlet
Ethernet Specifications
Ethernet specifications use the following pins for communication:
Cat 5 Ethernet (100BASE-T) and below:
Pin 1: Tx+
Pin 2: Tx-
Pin 3: Rx+
Pin 4: Unused
Pin 5: Unused
Pin 6: Rx-
Pin 7: Unused
Pin 8: Unused
Tx is a pin used for transmitting. Rx is a pin used for receiving.
Cat 5e (1000BASE-T) and above:
Pin 1: Bi+
Pin 2: Bi-
Pin 3: Bi+
Pin 4: Bi+
Pin 5: Bi-
Pin 6: Bi-
Pin 7: Bi+
Pin 8: Bi-
Bi indicates the pin is used for both transmitting and receiving.
Auto-MDIX
Network devices that are capable of 1000 Mbps or faster speeds use a technology called auto-MDIX. With auto-MDIX, network ports are able to automatically change the sending/receiving pin positions depending on the connected device. This allows standard, straight-through network cables to be used for any device pairing (e.g., switch to switch or workstation to workstation). However, older devices with speeds slower than 1000 Mbps (i.e., 10/100 Mbps) are not capable of auto-MDIX and require a crossover cable when making the following device connections:
- Switch to switch
- Switch to hub
- Hub to hub
- Workstation to router
- Workstation to workstation
- Router to router
Fiber Optic Components
Fiber optic cabling is composed of the following:
A plastic or glass core that carries the signal.
A cladding that surrounds the core and maintains the signal as the cable bends.
A coating that protects the cladding and the core.
Single-mode fiber cable
- Transfers data through the core using a single light ray. The ray is also called a mode.
- Supports a large amount of data.
- Has a core diameter around 10 microns.
- Supports cable lengths that extend a great distance.
Multimode fiber cable
- Transfers data through the core using multiple light rays.
- Has a core diameter around 50 to 100 microns.
- Supports only limited distance cable lengths.
ST Connector (Fiber Optic Connector)
- Are used with single-mode and multi-mode cabling.
- Have a keyed bayonet-type connector.
- Are also called a push-in and twist connector.
- Have a separate connector for each wire.
- Are nickel-plated and have a ceramic ferrule to ensure proper core alignment and prevent light ray deflection.
- Are referred to as Set-and-Twist or Straight Tip.
SC Connector (Fiber Optic Connector)
- Are used with single-mode and multi-mode cabling.
- Have a push-on/pull-off connector that uses a locking tab to maintain connection.
- Have a separate connector for each wire.
- Use a ceramic ferrule to ensure proper core alignment and prevent light ray deflection.
- Are referred to as Set-and-Click or Square Connector.
LC Connector (Fiber Optic Connector)
- Are used with single-mode and multi-mode cabling.
- Are composed of a plastic connector with a locking tab that is similar to a RJ45 connector.
- Use a single connector with two ends to keep the two cables in place.
- Use a ceramic ferrule to ensure proper core alignment and to prevent light ray deflection.
- Are half the size of other fiber optic connectors.
- Are referred to as Lift-and-Click or Little Connector.
