Ethernet Flashcards
(19 cards)
What layers do Ethernet operate in?
Data Link(Layer 2) and Physical layer(Layer 1)
Which two acronyms represent the data link 802.11 sublayers that Ethernet relies upon to operate?
Logical Link Control (LLC) and MAC
What is the minimum Ethernet frame size?
64 bytes
What is the maximum Ethernet frame size?
1518 bytes ~ 1500 bytes
What are the frames that are less than 64 bytes called?
“Collision fragment” or “runt frame”. They are automatically discarded by receiving stations.
What are the frames called that are greater than 1518 bytes?
Jumbo or “baby giant frames”.
What happens with the frame if the size is less than 64 bytes?
The receiving device drops the frame
What happens with the frame if its bigger than 1518 bytes?
The data is either fragmented into smaller frames, or dropped.
How many bits in a Ethernet MAC address?
48 bits (4 per hexadecimal digit) → 6 bytes
Who establishes the rules for the MAC address?
IEEE
What are the two portions of the MAC address?
OUI (Organizationally Unique Identifier) and a vendor assigned code (for the NIC). 24 bits each.
Why was MAC addresses created?
MAC addresses were created to identify the actual
source and destination
What does a device do when forwarding a message to an Ethernet network?
Attaches the source and destination MAC address into a header.
How does a switch build its MAC address table?
- The switch examine all incoming frames for a new source MAC info to learn
- MAC address unknown? → Add to table + port number
- MAC address already exist? → Refresh timer for it (The switch keeps an entry in the table for 5 minutes by default)
What is the process for forwarding destination MAC address?
Destination MAC address in table? → Send it to specific port
Destination MAC address NOT in table? → Send the frame as broadcast
What are the 2 forwarding methods?
Store-and-forward - The switch stores the entire frame in internal memory and check the frame for errors before forwarding the frame to its destination. Bad frames are discarded.
What is Auto-MDIX(Automatic medium-dependent interface crossover)
The switch detects the type of cable attached to the port and configures accordingly.
What is ARP?
ARP(Address Resolution Protocol) is a protocol used for discovering MAC addresses linked to IPv4 IP-addresses in a network.
How does ARP work?
ARP broadcasts a request packet to all the machines on the LAN and asks if any of the machines are using that particular IP address. When a machine recognizes the IP address as its own, it sends a reply so ARP can update the cache for future reference and proceed with the communication.
