"Carrier sense, multiple access/collision detection."

Determines which computer should use a shared cable within a given moment.

1) A hub repeats information on every port, whereas a switch remembers (has "smarts") the MAC addresses of certain computers, creating point-to-point communication.

2) When you first turn on a switch, it acts exactly as though it were a hub, passing all incoming frames right back out to all the other ports. As it forwards all frames, however, the switch copies the source MAC addresses and quickly (usually in less than one second) creates an electronic table of the MAC addresses of each connected computer.

An electronic repeater -- it interprets 1s and 0s coming in from one port and repeats the same signal out to the other connected ports.

They read incoming signals and send new copies of that signal out to every connected port on the hub. 

1) Daisy chain 

2) Extended Star

- Use the Uplink port to connect up to 4-hubs together.

- Insert one end of a cable to the uplink and the other cable to any one of the regular ports.

1) When connecting devices of the same type, use crossover cables:

Special Twisted Pair cables that reverse the sending and receiving pairs on the end of the cables. 

2) When connecting devices of different types, use straight-through cables: regular cable.

1) Use a crossover cable.

2) Use a straigh-through cable if the hubs/switches have an uplink port.                                               

(insert one end of a cable to the uplink and the other end to any one of the regular ports)

Half-Duplex: 

- Provides communication in both directions, but only one direction at a time (not simultaneously).

- Once a party begins to receive a signal, it must wait for the transmitter to stop transmitting, before replying.

(e.g.,: Walkie-Talkie)

Full-Duplex:

- Provides communication in both directions, simultaneosly. 

Which of the following is a duplex fiber-optic connection?

A) LC

B) RJ-45

C) ST

D) SC

A) LC

1) The Preamble

2) MAC address of the frame's recipient

3) MAC address of the sending system

4) The length of data

5) The data itself

6) A pad

7) A frame check sequence, called a cycle redundancy check (CRC).

It allows switches to detect bridge loops. (Bridge loops create a path sending packets in an endless loop and preventing the network from working)

If detected, the switches communicate with each other and, without any outside interaction, turn off one port on the loop. 

Test Specific!

List a few facts about Ethernet standards:

1) There are only 4 speeds: 10 mb, 100 mb, 1 gigabit and10 gigabit.

2) Early versions of Ethernet use either UTP or Fiber.

3) Early versions of Ethernet networks use either a hub or switch.

4) Only 10- and 100-megabit Ethernet may use a hub. Gigabit and 10-Gigabit Ethernet Networks must use a switch.

5) Every version of Ethernet has a limit of 1,024 nodes.

6) Every UTP cable has a max distance from the switch/hub to the node of 100 meters.

·      Speed:                 10 Mbps

·      Signal type:         Baseband                      

·      Distance:             100 meters 

·      Node limit:          No more than 1,024 nodes per hub

·      Topology:            Star-bus: Physical star, Logical  

                                               bus

·      Cable type:         CAT 3 and up, RJ-45 connectors

- A Fiber-Optic version, because:

• Signal can travel further
• Immune to EMI
• Much more difficult to tap into

- Uses Multimode (LED) cables.

- Full-Duplex systems.

- HERE ARE THE SPECS:

Speed:                          10mbps

Signal type:              Baseband

Distance:                     2,000 meters

Node Limit:                 1,024

Topology:                    Star-bus: Physical star, Logical bus

Cable Type:             Multimode cables with ST or SC

                              connectors

Speed:                          100 mbps

Signal type:              Baseband

Distance:                     100 meters

Node Limit:                 1,024

Topology:                    Star-bus: Physical star, Logical bus

Cable Type:             CAT 5(e) or better, RJ-45 Connectors

Speed:                          100 mbps

Signal type:              Baseband

Distance:                     2 kilometers

Node Limit:                 1,024

Topology:                    Star-bus: Physical star, Logical bus

Cable Type:             Multimode cables with ST or SC

                              connectors

Describe 1000BaseT Ethernet...

(A) 1,000 Gbps (B) most widely implemented solution

Cabling:                   CAT 5(e) or 6

Cable Details:           4-pair, Full Duplex

Connectors:              RJ-45

Length:                    100 meters

Describe 1000BaseCX....

(phased out)

Describe 10GBaseSR Ethernet  

(Short Wavelength)

(10,000 gbps)

Describe 10GBaseSW

(Short Wavelenth)

Describe 10GBaseLR

(Long Wavelength)

Describe 10GBaseLW

(Long Wavelength)

Describe 10GBaseER

(Extra-long wavelength range)

Describe 10BaseEW

(Extra-long wavelength range)

Ethernet hubs take an incoming packet and ____ it out to the other connected ports.

A) Amplify

B) Repeat

C) Filter

D) Distort

Repeat.

Hubs are nothing more than multiport repeaters.

What type of bus does 10BaseT use?

A) Bus

B) Ring

C) Star bus

D) Bus ring

What is the maximum distance that can separate a 10BaseT node from its hub?

A) 50 m

B) 100 m

C) 185 m

D) 200 m

When used for Ethernet, UTP uses what type of connector?

A) RG-58

B) RJ-45

C) RJ-11

D) RS-232

RJ-45 connectors are used in UTP cables for Ethernet

(10Base2 networks use RG-58 coaxial cable connectors)

(RJ-11 is the standard 4-wire connector used for phone lines)

(RS-232 is a standard for serial connectors)

What is the maximum number of nodes that can be connected to a 10BaseT hub?

A) 1,024

B) 500

C) 100

D) 185

Which of the following is not true of crossover cables?

A) They are a type of twisted-pair cabling.

B) They reverse the sending and receiving wire pairs.

C) They are used to connect hubs.

D) Both ends of a crossover cable are wired according to the TIA/EIA 568B standard.

D. One end is wired according to the TIA/EIA 568B standard, while the other is wired according to the TIA/EIA 568A standard.

This is what crosses the wire pairs and enables two hubs to communicate without colliding.

Which of the following connectors are used by 10BaseFL cable? (select 2)

A) SC

B) RJ-45

C) RJ-11

D) ST

Which networking devices can use the Spanning Tree Protocol (STP) ?

A) Hubs

B) Media converters

C) UTP cables

D) Switches

Switches

The STP is unique to switches.

What device filters and forwards traffic based on MAC addresses?

A) Router

B) Hub

C) Bridge

D) Switch

Bridge

Any device that filters and forwards traffic based on MAC addresses is by definition a bridge.

How many pairs of wires do 10BastT and 100BaseT use?

A) 4

B) 1

C) 3

D) 2

Which standard does 802.3ab describe?

A) 1000BaseLX

B) 1000BaseT

C) 1000BaseCX

D) 1000BaseSX

1000BaseT

(known as Gigabit Ethernet)

What is the maximum distance for the 1000BaseLX without repeaters?

A) 1 mile

B) 2,500 meters

C) 20,000 feet

D) 5,000 meters 

What is a big advantage of using fiber-optic cable?

A) Fiber is common glass, and therefore cheaper.

B) Fiber is not affected by EMI.

C) Making custom cable length is easier with fiber.

D) All that orange fiber looks impressive in the network closet.

What is the standard connector for the 10-GbE fiber standard?

A) ST

B) SC

C) MT-RJ

D) There is no standard

55 meters

With CAT 6, 10GBaseT is limited to 55 meters.