CCNA1 Intro to Networks: Chapter 5 (Section 5.1.1)
What IEEE standards define Ethernet?
802.2 and 802.3
What is a "collision fragment"?
A frame that is less than 64 bytes in length (aka a "runt frame").
What is a "baby giant" frame?
A frame with more than 1500 bytes of data (aka a "jumbo" frame).
What is the underlying logical topology of Ethernet?
A multi-access bus (i.e. all nodes (devices) on a single network segment share the medium)
What is the Type (aka EtherType, or Length) field?
It describes which higher-layer protocol has been used OR how many bytes. It's 2 octets.
What is the purpose of the Frame Check Sequence (FCS) field?
It detects errors in an Ethernet frame. It's 4 octets.
Data encapsulation provides what three functions?
Frame delimiting, addressing, and error detection
What does the LLC do?
It handles the communication between the upper layers and the lower layers
What is the CSMA/CD for?
It is used in half-duplex Ethernet LANs to detect and resolve collisions
Describe the arrangement of an Ethernet frame structure.
1. Preamble (7 Bytes); 2. Start Frame Delimiter ((SFD) 1 Byte) 3. Destination MAC address (6 Bytes) 4. Source MAC address (6 Bytes) 5. Type (2 Bytes) 6. Data (46-1500 Bytes) 7. Frame Check Sequence ((FCS) 4 Bytes)
When was Ethernet created?
1973
What does "contention-based method" mean?
Any device can try to transmit data across the shared medium whenever it has data to send
What does the Destination MAC address field do?
Assists a host in determining if the frame received is addressed to it. It's 6 octets.
What does the Start of Frame Delimiter (SFD) field do?
Byte-level synchronization of sending and receiving devices for frame delivery. It's 1 octet.
What does "CSMA/CD" stand for?
Carrier Sense Multiple Access/Collision Detection
What are the two primary responsibilities of the MAC sublayer?
Data encapsulation and media access control
What frame format is used in TCP/IP networks?
Ethernet II
What does frame delimiting do?
It provides important delimiters that are used to identify a group of bits that make up a frame.
Ethernet operates on what two sublayers of the data link layer?
Logical Link Control (LLC) and Media Access Control (MAC)
What does the Preamble field do?
Notifies destination to get ready for a new frame using alternating 1s and 0s. Provides bit-level synchronization. It's 7 octets.
Ethernet operates on what two layers of the OSI model?
Physical (Layer 1) and Data Link (Layer 2) (aka, TCP/IP Network Access Layer)
What is the Source MAC address field?
The frame's originating NIC or interface MAC address. It's 6 octets.
What does the Data field of a frame do?
Uses Padding to increase the frame's field to at least 64 bytes. It's anywhere from 46-1500 octets. It contains both the Destination IP address (4 octets) and the Source IP address (4 octets).
