1.6 Selecting Cable typs

Carrier sense multiple access with collision detection(CSMA/CD)- Protocol used to allow two devices that share the same bandwidth evenly while preventing them from transmitting simultaneously.

Host checks for presence of digital signal on the wire. If the wire is clear it will proceed with transmission
Transmitting host constantly monitors the wire to make sure no other hosts are transmitting. If it detects another signal it sends out an extended Jam signal that causes all other hosts to stop sending data.
The nodes respond to the jam signal by waiting a bit before attempting to resend the data. Back off Algorithm determines this time.

Half Duplex Vs Full Duplex

Half duplex only uses a single pair of wires. This means if two hosts communicate at the same time there will be a collision
Full duplex uses two pairs. Transmitted data is sent on a different pair of wires then received. This prevents collisions.

Cabling Standards-

10Base-T(IEEE 802.3)- 10 Mbps- Cat 3 Cable unsheilded twisted pair(UTP)- 100 meters max length
100Base-T(IEEE 802.3u)-Fast Ethernet- Cat 5, 5e or 6 Cable. 100 meters max length
1000Base-CX(IEEE 802.3z)- 62.5/125 Micron multimode fiber-412 meters max length
1000Base-T(IEEE 802.3ab)- Cat 5 4 pair UTP- 1 Gbps- 100 meters max length
1000Base-SX(IEEE 802.3z)- 1 gig ethernet running over fiber rather then copper- Short wavelength laser- 62.5 and 50 Micron core Multimode fiber- 850 Nanometer laser- 220 meters max length for 62.5 micron and 550 meters with 50 micron.
1000Base-LX(IEEE 802.3z)-Single mode fiber-9 micron core- 1300 nanometer laser- 3 Kilometers to 10 Kilometers.
1000Base-ZX(Cisco Standard)- Works on standard single mode- 70 KM max length
10GBase-T(802.3.an)- 10 Gbps- cat 5e, 6 and 7 UTP cable- 100 meters max length

Ethernet Cabling

Straight through cable
- Connects host to switch of hub, Router to switch of hub
- Pairs required for 10/100 1 to 1, 2 to 2, 3 to 3, 6 to 6.
Crossover cable-
- Switch to switch, host to host, hub to hub, Hub to switch, router direct to host, router to router
- pairs- 1 to 3, 2 to 6 on each side.
UTP gigabit wiring(1000Base-T)\
- Uses all 4 pairs unlike 10/100.
- Still matches straight through 1 to 1, 2 to 2 and so on
Rolled Cable-
- Used to connect a host to the console of a router or switch
- 1 to 8, 2 to 7, 3 to 6 and so on

Fiber Optics

Core- Contains the light waves
Cladding- confines the light to the core- the tighter the cladding the smaller the core. The smaller the core the farther and faster the light will travel.
Buffer- Protects the glass

Fiber Types-

Single Mode- Smaller core with much tighter cladding- Allows only a single mode of light to travel through
Multimode- Looser cladding- Allows multiple particles of light to travel through the glass

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