A data-link frame’s trailer contains several important entities: the Frame Check Sequence (FCS), which is a cyclic redundancy check (CRC) used to detect errors in the frame; the end of frame delimiter (EOF), which signals the end of the frame; the starting flag, which indicates the start of the frame; and the stop flag, which indicates the end of the transmission.
Inside a Data-Link Frame Trailer
Trailers are often overlooked, but they play a critical role in data-link frames. They ensure that frames are received correctly and gracefully handle errors. Here’s a closer look at what’s inside a data-link frame trailer.
Frame Check Sequence (FCS)
- The FCS is a checksum that ensures data integrity.
- It’s calculated based on the data in the frame and appended to the trailer.
- The receiver recalculates the FCS and compares it to the received FCS.
- If the two FCS values match, the frame is considered valid; otherwise, it’s discarded.
Control Field
- Contains information about frame management.
- Typically includes fields for:
- Acknowledgement (ACK): Indicates successful receipt of the frame.
- Sequence Number: Identifies the frame within a sequence.
- Window Size: Specifies the number of frames that can be sent before an acknowledgement is required.
End of Frame (EOF)
- Signals the end of the frame.
- Allows the receiver to identify the boundaries of the frame and start processing the data.
- Typically indicated by a specific bit sequence or character.
| Field | Purpose |
|---|---|
| FCS | Data integrity check |
| Control Field | Frame management |
| End of Frame (EOF) | Frame boundary indicator |
Question 1:
What data is contained within the trailer of a data-link frame?
Answer:
The trailer of a data-link frame contains the following data:
- Frame Check Sequence (FCS): A checksum used to detect errors in the data portion of the frame.
- Delimiter: A special character sequence that marks the end of the frame.
Question 2:
What is the purpose of the destination address field in a data-link frame?
Answer:
The destination address field in a data-link frame specifies the physical address of the intended recipient of the frame.
Question 3:
How is the length field of a data-link frame used?
Answer:
The length field of a data-link frame indicates the number of bytes in the data portion of the frame. This information is used by the receiving device to determine where the end of the frame is located.
Thanks for taking the time to learn about the contents of a data-link frame trailer. Understanding this technical stuff can be a bit like navigating a maze, but I hope this article shed some light on the subject. If you still find yourself scratching your head, feel free to drop me a line.
I’ll be here, waiting to dive deeper into the world of data communication with you. So, stay tuned and visit again soon!