Framing in Computer Networks
A point-to-point wired connection between two computers or devices that transmits data in a stream of bits is called framing. These fragments, nevertheless, need to be organized into recognizable informational blocks. One function of the data connection layer is framing.
It gives a sender a means of sending a collection of bits that the recipient can understand. Each data link layer technology has its own frame structure, including Ethernet, token rings, frame relays, and others. Error-checking codes and other information are contained in the headers of frames.
Digital transmission, especially in computer networks and telecommunications, is measured in frames. When it comes to light energy, frames are analogous to the energy packets known as photons. The Time Division Multiplexing operation continuously uses frames.
Types of Framing in Computer Networks
The technique of packaging data into frames for transmission at the data link layer is known as framing in computer networks. Two primary categories of framing exist:
- Fixed-Size Framing
- Variable-Size Framing
1. Fixed-Size Framing
Because the frame's dimensions are preset, fixed-size framing is simple. One typical example is an ATM cell. Since the receiver is aware of the frame's length from the beginning, no extra delimiters are required in this instance. Since the frame's length serves as a delimiter, there is no need to give borders because it is a constant size.
2. Variable-Size Framing
Frames of different lengths can be created using variable-size framing, which calls for systems to mark the transition between frames. This strategy employs two main techniques:
Length Field:
In Ethernet, a field inside the frame indicates its overall length.
End Delimiter:
As seen in Token Rings, a particular pattern (flag byte) is utilized to indicate the end of a frame. Byte stuffing and bit stuffing are methods used to prevent data with this delimiter pattern from being misinterpreted.
- Byte Stuffing:
The process of "stuffing" data to prevent conflicts involves adding a unique byte to the data stream to distinguish it from the delimiter.
- Bit Stuffing:
This technique inserts bits to distinguish the delimiter at the bit level, much like byte stuffing.
There are further difficulties with framing at the Data Link Layer, such as:
Synchronization:
Correct transmission and reception of data frames depend on synchronization. Synchronization can be difficult, though, especially in high-speed networks where frames are sent quickly.
Error detection:
Checksums and CRCs are two methods used by Data Link Layer protocols to identify errors in the data that is being transferred. These methods are not infallible, though, and they may overlook certain kinds of mistakes.
Bit stuffing:
Bit stuffing is a technique that involves adding extra bits to the data stream in order to prevent the data from being perceived as control characters. On the other hand, bit stuffing can raise the transmission overhead and cause synchronization problems.
Efficiency:
But bit stuffing might cause synchronization problems and raise the transmission overhead. Using available bandwidth effectively is essential to guaranteeing fast and dependable data transmission. However, the overall transmission efficiency may be lowered by the costs related to error detection and framing.
