Block 7 Flashcards
_______ ________ consists of the data link later specifications that often define how devices are to be physically and logically connected.
Network topology
Ex. Bus & Ring topologies
________ __________ defines how devices are addressed at the data link layer.
Physical Addressing.
Also known as: physical, hardware, machine, or MAC addresses
_____ _________ uses Cyclic Redundancy Check (CRC) or Frame Check Sequences (FCS) to detect errors in transmissions.
Error detection and notifications
What reorders frames that are received out of sequence?
Sequencing of data frames
____ ______ moderates the transmission of data so that the receiving device is not overwhelmed with more traffic that it can handle at one time.
Flow control
What is the PRIMARY METHOD of flow control for switches?
Buffering
________ is a forwarding technique used in packet-switched networks.
Bridging
________ devices depend on flooding and examination of source addresses in received packed headers to locate unknown devices.
Bridging Devices
True/False?
Bridges are considered software based.
True
True/False?
Switches are hardware based devices that use Application Specific Integrated circuits(ASIC) for faster operation.
True
True/False?
Bridges have advance Spanning-Tree control.
False
Bridges have limited Spanning-Tree control.
True/False?
Switches have limited Spanning-Tree control.
False.
Switches have ADVANCE Spanning-Tree control
Bridges can have up to __ ports.
Up to 16 ports
Switches can have _________ of ports
Hundreds.
Only limited by the amount of ports available.
Q.1 _________ domain is a physical or logical network segment in which data lackeys can collide with each other.
Q.2 What reduces this from happening?
- Collision domain
2. CSMA/CD
_________ domain is a logical network segment defined by it’s router port connection.
All network devices can communicate with each other by using broadcasts.
Broadcast Domain
255.255.255.255
Switches use ____ to build and maintain MAC address tables.
Application-Specific Integrated Circuits (ASIC)
Layer 2 switches are built to provide what 4 things?
Hardware-based bridging
Wire speed
Low latency (low delay)
Low cost
What are considered the MOST COMMON type of switches?
They provide network segmentation by breaking up collision domains
Ethernet Switches
What are the MAJOR switch functions?
(A)ddress Learning
(L)oop Avoidance
(F)orward/Filter Decision
Which major switch function does this fall under?
The switch has no choice but to flood the network with this frame because it just try and learn the location of the destination device.
(A)ddress Learning
Under the major switch functions what happens if a workstation does not talk for a period of time on a network?
Chances are that it’s MAC address heads aged out (removed) from the table.
If the destination hardware address is known and listed in the database, then the frame is _________ out only on the correct exit interface.
Forwarded
This helps preserve bandwidth on the other network segments
Frame filtering
What are the 3 switching methods?
Store & Forward
Cut-Through (Real Time)
Fragment Free (Modified Cut-Through)
(SaCF)
With this frame switching method, the switch copies the entire frame into it’s buffers and computes the CRC (Cyclic Redundancy Check). If no errors are present the MAC address is used to determine the appropriate interface to use.
Store & Forward
This method is BEST for sending error free frames but consumes the greatest amount of processing time
This frame switching method provides reduced latency. Provides no error checking but results in the fastest processing time.
Cut-Through (Real Time).
LAN switch copies only the destination (first 6 bytes)
In this frame switching method the switch waits for the COLLISION WINDOW (64 bytes) to pass before forwarding.
Fragment Free ( Modified Cut-Through)
Better error checking than the cut-through mode, with practically no increase in latency
Switches or Bridges in a network environment can create what is referred to as a “____ ____ __ _____”
Single point of failure
A ____ is simply having more than one path to a destination that causes instability in the MAC address table.
Loop
The instability of of loops causes why 3 things?
Broadcast Storms
Multiple Frame Copies
Multiple Lopps
When referring to loop avoidance if the switches flood broadcasts endlessly throughout the internetwork it’s called….?
Broadcast Storms
When referring to loop avoidance problems; _______ _______ ______ Is when a device can receive multiple copies of the same frame because the frame can arrive from different segments at the same time.
Multiple Frame Copies
MAC address filter table will be confused. Constantly updating the MAC filter table
In reference to loop avoidance this is one if the BIGGEST PROBLEMS.
Multiple Loops
Loops can occur within other loops
This protocol is used by layer 2 devices to STOP NETWORK LOOPS in networks that have more than one physical link to the same network.
Spanning Tree Protocol
Designed to detect loops and close or open the necessary ports to avoid such loops.