Version etc frame diagram header metadatapayload datamedium access control basic ethernet

COMP247 Week 2 Lecture 2

Local Area Networks:


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	Switched Ethernet – uses switches.

Ethernet Address
Every device in the world is assigned a unique Ethernet address. – where you want the message sent at a hardware level these are data-link addresses. Different LANs all have different addresses that are in different formats and sizes in 48-bit numbers.

Ethernet Frame Structure:

Data is a collection of facts about something
Metadata is a collection of facts about data (data about data)

Medium Access Control:

In basic Ethernet, all the nodes are connected to the bus. When we have to control multiple nodes sending messages on the actual connections we need Medium Access Control (MAC). Ethernet uses a protocol called CSMA/CD that acts as a traffic controller for the frames sent in by the nodes.

takes a weak input signal, regenerates it, and transits it on all output lines. A hub enables communication only between same types of LANs.

Cut-through Switching:

 Tends to have low latency but may waste disk capacity from error messages

then transmit it

 Less wasted capacity but slower latency.

 Perform error check, if ok start transmitting

Lan Security:

than the correct one for the destination host

Control – physically secure the network ports