Term
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Definition
| Local Area Network. Layer 1 and 2 standards designed to work together for the purpose of implementing geographically small networks. |
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Term
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Definition
| A family of standards that together define the physical and data link layers – speed supported, types of cabling and allowed length of cabling. |
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Term
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Definition
| Unshielded Twisted Pair - Inexpensive copper cabling. Less secure, allows for shorter distances between devices. |
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Term
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Definition
Institute of Electrical and Electronics Engineers -
Since the early 1980s, this group has been responsible for LAN standardization process. Physical layer – differences in speed and types of cabling. Data link layer – 802.3 Media Access Control sublayer and 802.2 Logical Link Control sublayer. |
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Term
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Definition
| Network Interface Card - Resides inside the PC; allows communication between computer and network/Internet. Each NIC has a unique address. |
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Term
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Definition
| Early LANs in which a single electrical bus was created with coaxial cable and Ethernet cards. Signals (frames) are transmitted to all stations on the LAN, like a school bus stopping at every house. 10BASE5 – 500m of cable max, 10BASE2 – 185m of cable max [almost 200m]. Both ran 10Mbps. |
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Term
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Definition
| Carrier Sense Multiple Access with Collision Detection - Algorithm that defines how the bus is accessed. Originated with 10BASE5 and 10BASE2 but is used for any single bus system. Device waits until LAN is silent before sending frame. If collision occurs, devices wait a random amount of time then resend. Collisions occur when two stations transmit at the same time. Electronic signals overlap causing a collision. CSMA/CD detects and recovers from collisions. |
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Term
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Definition
| Used when longer cable lengths are needed. Attenuation occurs when cable length is longer than signal is capable of sending – the signal dies away. Repeater connects to multiple cable segments, receives electrical signal on one cable, generates a new, clean, strong signal, and sends it out other cable. Repeaters do not amplify the signal as that would also amplify any noise picked up along the way. |
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Term
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Definition
| Basically, a repeater with multiple physical ports. Collisions still occur, so CSMA/CD access rules continue to be used. Hubs create a single electrical bus that is shared the devices that are connected to it. All devices share the same bandwidth available through the hub. All devices on a hub are in the same collision domain since it is a single electrical bus. Hubs are layer 1 since they are only physical. |
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Term
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Definition
| Interpret bits in the received frame and send it to the required port, not all ports. The switch buffers frames in memory, sending one at a time, thereby avoiding collisions. Switches do NOT share bandwidth - a switch with 100Mbps ports has 100Mbps for each port. A switch’s logic requires that the switch look at the Ethernet header (to locate recipient). Switches are a layer 2 device since they look at data. |
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Term
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Definition
| Two or four pairs of wires with an outer jacket of flexible plastic for support, as wires are brittle. Each wire also has a thin plastic coating to help prevent breakage; coating is color-coded for ease of identification. Ends of wires are inserted into a connector, typically RJ-45. Wires create magnetic fields when electric current passes through. By twisting pairs, with current traveling in opposite directions, magnetic fields mostly cancel each other out, thus eliminating/reducing electrical noise. |
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Term
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Definition
| Has eight pin positions into which UTP cable wires are inserted. Connector is inserted into RJ-45 port. An RJ-45 connector is slightly wider, but is otherwise similar to a standard telephone cable (RJ-11) connector. |
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Term
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Definition
| Have physical ports that can be changed without purchasing a whole new switch. Small removable devices support use of a variety of connectors, types of cables, and cable lengths. |
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Term
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Definition
| Electronics Industry Alliance, Telecommunications Industry Association - Define standards for UTP cabling, color-coding for wires, and standard pinouts for cables. |
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Term
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Definition
| Wire at pin 1 on one end of the cable goes to pin 1 at the other end of the cable; 2 to 2, 3 to 3, etc. Both ends of the cable use the same EIA/TIA pinout standard on each end. Used when devices use opposite pins for transmitting data: One device transmits 1,2 and receives 3,6. Other device transmits 3,6 and receives 1,2. |
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Term
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Definition
| Used when connecting two devices that both use the same pins to transmit – the pinouts need to be set up to swap the pair. Example, between switches 1,2 and crosses to 3,6. |
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Term
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Definition
| Cables that connect switches. Crossover cables are required since switches transmit on 3,6 and receive on 1,2. |
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Term
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Definition
| Defines the set of devices whose frames could collide. All devices on a hub are in the same collision domain since it is a single electrical bus. Devices in the same collision domain use CSMA/CD. |
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Term
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Definition
| Device sends or receives but never both at the same time. Creates performance issues. Hubs are half duplex devices. |
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Term
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Definition
| Device can send and receive concurrently. With full duplex, CSMA/CD is disabled for devices on both ends of the cable. Performance is doubled by allowing simultaneous transmission in both directions. |
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Term
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Definition
| Organizationally Unique Identifier - The first half of the MAC address identifies the manufacturer with a code assigned by IEEE. The second half of the MAC address is a number the manufacturer has never used on another card. |
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Term
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Definition
| Frame Check Sequence - Allows a device receiving an Ethernet frame to detect whether the bits have changed during transmission (typically due to electronic interference). Not recovery - damaged frame is discarded not retransmitted. FCS is the last field in the frame. |
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Term
| What are the three components of a LAN? |
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Definition
| 1) Computers that have an Ethernet network interface card (NIC) installed, 2) Ethernet hub or switch, and 3) UTP cables to connect each PC/station to the hub or switch. |
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Term
| What are the four functions of a LAN? |
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Definition
File sharing
Printer sharing
File transfers (FTP server software needed)
Gaming (multi-player) |
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Term
| List the speed, IEEE Standard, cable type, maximum cable length, common name, and UTP cable information for 10BASE-T. |
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Definition
Speed: 10 Mbps (Megabits per second)
IEEE Standard: 802.3
Cable Type: copper
Max. Cable Length: 100 m
Common Name: Ethernet
UTP Cable Pairs: Two pairs, straight-through or crossover. 1,2 with 3,6 |
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Term
| List the speed, IEEE Standard, cable type, maximum cable length, common name, and UTP cable information for 100BASE-TX. |
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Definition
Speed: 100 Mbps (Megabits per second)
IEEE Standard: 802.3u
Cable Type: copper
Max. Cable Length: 100 m
Common Name: Fast Ethernet
UTP Cable Pairs: Two pairs, straight-through or crossover. 1,2 with 3,6 |
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Term
| List the speed, IEEE Standard, cable type, maximum cable length, common name, and UTP cable information for 1000BASE-T. |
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Definition
Speed: 1000 Mbps (Megabits per second)
IEEE Standard: 802.3ab
Cable Type: copper
Max. Cable Length: 100 m
Common Name: Gigabit Ethernet
UTP Cable Pairs: Four pairs, transmits and receives simultaneously, straight-through or crossover. 1,2 with 3,6 and 4,5 with 7,8 |
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Term
| List the speed, IEEE Standard, cable type, maximum cable length, and common name for 1000BASE-LX. |
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Definition
Speed: 1000 Mbps (Megabits per second)
IEEE Standard: 802.3z
Cable Type: fiber
Max. Cable Length: 5 Km
Common Name: Gigabit Ethernet |
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Term
| List the speed, IEEE Standard, cable type, maximum cable length, and common name for 1000BASE-SX. |
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Definition
Speed: 1000 Mbps (Megabits per second)
IEEE Standard: 802.3z
Cable Type: fiber
Max. Cable Length: 550 m
Common Name: Gigabit Ethernet |
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Term
| Identify points from early LANs (10BASE5, 10BASE2) regarding device connection, collisions, extending the length of LANS. |
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Definition
Original Ethernet LANs created on single electrical bus to which all devices connected.
Ethernet defined the CSMA/CD algorithm which avoids collisions and takes action when collisions occur.
Repeaters extended the length of LANs by cleaning up the electronic signal and repeating it – a Layer 1 function – but without interpreting the meaning of the signal. |
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Term
| Identify devices that transmit on 1,2 and receive on 3,6 |
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Definition
PC NIC
Router
Wireless Access Point
Networked Printer |
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Term
| Identify devices that transmit on 3,6 and receive on 1,2 |
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Definition
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Term
| Identify and describe three performance issues regarding CSMA/CD |
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Definition
Half duplex – Device sends or receives but never both at the same time.
During collisions, no useful data makes it across the LAN and offending devices have to wait longer to use the LAN.
Increased Ethernet utilization increases the statistical chance of collisions. |
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Term
| Six traits of LAN Addressing |
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Definition
- Identifies individual devices or groups of devices.
- 6 bytes long
- Written in hexidecimal
- Typically written with a period between each set of four hex digits.
- IEEE requires globally unique unicast MAC address on all LAN interface cards.
- IEEE calls them MAC addresses because MAC (Media Access Controls) protocols define addressing details. |
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Term
| Structure of unicast Ethernet Address |
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Definition
OUI - 24 bits / 6 hex digits
followed by
Vendor Assigned - 24 bits / 6 hex digits |
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Term
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Definition
| Media Access Control - 802.3 (Ethernet) defines the MAC sublayer of IEEE Ethernet. |
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Term
| Identify three alternate names for MAC Address |
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Definition
Ethernet Address
NIC Address
LAN Address
These terms describe the 6-byte address of the LAN interface card. |
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Term
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Definition
| The 6-byte address assigned by the vendor making the card. This address is burned into the interface card itself. |
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Term
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Definition
| A term for a MAC that represents a single LAN interface. |
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Term
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Definition
| An address that means “all devices that reside on this LAN right now.” |
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Term
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Definition
| Some subset of all the Ethernet devices currently on the Ethernet LAN. |
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Term
| Identify field length (bytes) and describe the Ethernet and Header/Trailer Field: Preamble |
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Definition
Field Length in Bytes: 7
Description: Synchronization |
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Term
| Identify field length (bytes) and describe the Ethernet and Header/Trailer Field: SFD |
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Definition
Start Frame Delimiter (SFD)
Field Length in Bytes: 1
Description: Signifies that the next byte begins the Destination MAC field. |
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Term
| Identify field length (bytes) and describe the Ethernet and Header/Trailer Field: Destination MAC Address |
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Definition
Field Length in Bytes: 6
Description: Identifies the intended recipient of this frame. |
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Term
| Identify field length (bytes) and describe the Ethernet and Header/Trailer Field: Source MAC Address |
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Definition
Field Length in Bytes: 6
Description: Identifies the sender of this frame. |
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Term
| Identify field length (bytes) and describe the Ethernet and Header/Trailer Field: Length |
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Definition
Field Length in Bytes: 2
Description: Defines the length of the data field of the frame (either length or type is present, but not both). |
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Term
| Identify field length (bytes) and describe the Ethernet and Header/Trailer Field: Type |
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Definition
Field Length in Bytes: 2
Description: Defines the type of protocol listed inside the frame (either length or type is present, but not both). |
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Term
| Identify field length (bytes) and describe the Ethernet and Header/Trailer Field: Data and Pad |
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Definition
Field Length in Bytes: 46-1500
Description: Holds the data from a higher layer, typically an L3 PDU (generic), and often an IP packet. |
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Term
| Identify field length (bytes) and describe the Ethernet and Header/Trailer Field: FCS |
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Definition
Frame Check Sequence
Field Length in Bytes: 4
Description: Provides a method for the receiving NIC to determine if the frame experiences transmission errors. |
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