Ethernet Flashcards
What are the two ways Data accesses the network and communicates and define them
Deterministic and Contention Based
Deterministic network access is very organised and orderly, requires an electronic token first in order to transmit
Contention based is chaotic and transmit whenever possible
Why does Ethernet use Contention Based?
Lower overhead leads to full use of bandwidth which leads to quicker speeds.
Describe how collisions are prevented in a network?
Collisions are prevented using the CSMA/CD protocol.
CSMA/CD is the Carrier sensing multiple access with collision detection. It works over wires
CSMA/CD works by listening for a signal (carrier sensing) if no activity is detected it will transmit. If it detects it will wait.
If it transmits, it will detect a collision, if no collision is detected, it will complete the transmission.
If a collision is detected it will set off a random back off timer and the re attempt transmission by listening for a signal all over again..
What is a drawback of having multiple devices on a single network segment
The more devices you have the more collisions you are going to have
List the network infrastructure devices and their broadcast and collision domains
Hub - 1 collision domain - 1 broadcast domain
Bridge - 1 collison domain per port - 1 broadcast domain
Switch - 1 collision domain per port - 1 broadcast domain
Router - 1 per port - 1 per port
What is 802.3ad and what does it do / what problem does it solve
802.3ad is a link aggregation, it combines multiple physical connections into a single logical connection to minimise or prevent congestion.
Name the two protocol numbers for PoE and their functions
PoE is Power over Ethernet in which Ethernet cable can provide both electrical power and data over Ethernet.
PoE can provide 15.4 watts and PoE+ can provide 25.5 watts
the numbers are 802.3af and PoE+ is 802.3at
What is 802.1x?
802.1x is user authentication and requires users to authenticate themselves before gaining access to the network
What is the protocol which prevents switching loops and broadcasting storms?
Spanning Tree Protocol - 802.1d
What is VLAN and what is its protocol number?
802.1Q and it allows for certain ports on a switch to be used for different broadcast domains. i.e ports 1-4 for marketing 5-10 for HR etc
This allows for the logical connection of devices without physical cabling
What is a firewall?
A Network security applicance placed at the boundary of a network. It allows for traffic to come from in of the network. and vice versa
