Module 1: ethernet stuff. Flashcards
the Networking Layer
What are becoming common ways to connect computing devices to networks?
Wireless and cellular
What connection method is the most common option you find in the workplace and data center, even today when wireless is available?
traditional cable networks
the protocol most widely used to send data across individual links. provide means for software at higher levels of the stack to send and receive data.
ethernet
primary purpose of the data link layer
so that the internet transport and application layers can all operate the same no matter how the device they are running on is connected
ethernet network access method that uses carrier sensing and collision detection to regulate how communication takes place over a shared transmission medium. Solves the problem of collision domains
carrier sense multiple access with collision detection. CSMA CD.
what determines when the communications channels are clear and when the device is free to transmit data.
csma cd
on ethernet, if no data is currently being transmitted on a network segment, what happens?
a node is free to send data
what happens if two or more computers try to send data at the same time on ethernet?
computers detect the collision and stop sending data. each device then waits a random interval of time before trying to send data again, which prevents all computers involved in the collision from colliding again.
why are Media Access Control addresses (MAC) important in a collision domain?
We can identify which node a transmission is actually meant for.
how many bits, groupings, and which digits are used in MAC addresses?
48 bits, represented by six groupings of two hexadecimal numbers. sixteen digits in hexadecimal, using a-f.
any number that can be represented by 8 bit
octet
what’s the total number of possible mac addresses that can exist
2^ 48, or 281474976710656 unique possibilities.
how many sections in a mac address
two
what are the first three octets (the first section) of a mac address known as
the organizational unique identifier, or OUI.
what is assigned to individual hardware manufacturers by the institute of electrical and electronics engineers, IEEE
OUI
what can I always identify purely by its mac address?
the manufacturer of a network interface
what are the last three octets of a mac address?
they can be assigned in any way the manufacturer wants with the condition that they only assign each possible address once, keeping all mac addresses unique globally
what ensures that the data sent over ethernet has an address for the machine that sends the transmission and the one that the transmission was intended for
Ethernet Mac Addresses
what the saving mac addresses do for devices on a network
they let nodes on a network know when traffic are attended for them
What is it when one device transmits data to another device. always meant for just one receiving address.
Unicast
What is done at the ethernet level by looking at a special bit in the destination mac address. if the least significant bit in the first octet of a destination address is set to zero, the ethernet frame is intended for only the destination address.
unicast
what happens if the least significant bit in the first octet of a destination mac address is set to zero?
the ethernet frame will be sent to all devices on the collision domain, but only received and processed by the intended destination
what happens if the least significant bit in the first octet of a destination mac address is set to one?
a multicast frame is sent to all devices on the local network segment. it will be accepted or discarded by each device depending on criteria aside from their own hardware mac address.
how can network interfaces accept lists of configured multicast addresses for these sorts of communications?
they can be configured