NWC204 Module 4 - 7: Physical and Data Link Layers

Vocabulary practice flashcards covering OSI Physical and Data Link layer concepts, Ethernet switching methods, and network topologies based on Module 4 - 7 notes.

OSI physical layer

The layer responsible for transmitting bits across the local media and creating signals that represent the bits in each frame.

Full-duplex connectivity

The reason why two strands of fiber are used for a single fiber optic connection.

Crosstalk

The distortion of the transmitted messages from signals carried in adjacent wires, often caused by the magnetic field around the adjacent pairs of wire.

Twisting opposing circuit wire pairs

The specific procedure used to reduce the effect of crosstalk in unshielded twisted-pair (UTP) copper cables.

Throughput

A measure of the transfer of bits across a medium over a given period of time, which can be influenced by the amount of traffic, types of traffic, and latency.

Bandwidth

The capacity at which a medium can carry data.

Latency

The amount of time, including delays, for data to travel from one point to another.

Goodput

The measure of usable data transferred over a given period of time.

Fiber-optic cable

A physical medium that uses the propagation of light, is not affected by EMI or RFI, and is more expensive than UTP cabling.

CRC (Cyclic Redundancy Check)

The value found in the FCS field of a frame used to verify the integrity of the received frame and determine if errors occurred during transmission.

Data link layer trailer

The part of a data-link frame that contains error detection information.

Partial mesh topology

A physical WAN topology that provides high availability and connects some, but not all, remote sites to a headquarters building.

Extended star topology

A topology where end devices connect to a central intermediate device, which in turn connects to other central intermediate devices.

Logical Link Control (LLC) sublayer

An Ethernet sublayer implemented in software that allows multiple Layer 3 protocols to use the same network interface and media.

Media Access Control (MAC) sublayer

The sublayer responsible for controlling the NIC for sending/receiving data on physical media and providing a mechanism for multiple devices to communicate over a shared medium.

CSMA/CD

An access method used in Ethernet where all network devices must listen before transmitting to manage collisions.

Auto-MDIX

A feature that enables a device to automatically configure an interface for either a straight-through or a crossover Ethernet cable connection.

Shared memory buffering

A method of memory buffering that works best for switching incoming frames from a $1000\text{BASE-T}$ port to a port connected to a $100\text{Base-T}$ network.

Store-and-forward switching

A switching method that receives the entire frame and performs a CRC check to detect errors before forwarding the frame.

Fast-forward switching

A cut-through switching method that provides the lowest level of latency appropriate for high-performance computing applications.

Fragment-free switching

A type of cut-through switching that stores the first $64\text{ bytes}$ of a frame before forwarding to ensure no collision has occurred.

Attenuation

The loss of signal strength as distance increases.

Modulation

The OSI physical layer term describing the process by which one wave modifies another wave.

Multicast MAC address

A specific type of address such as $01\text{-}00\text{-}5E\text{-}00\text{-}00\text{-}03$.

Straight-through cable

The type of UTP cable used to connect a PC directly to a switch port.

MAC Address Table

A table in a Cisco switch built using the source MAC addresses of frames and utilized to forward frames via the destination MAC address.