# Q2(c) · Framing

Subject: Computer Networks

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/cn/#tee/papers/paper-2023-ai-partial/q2c

Canonical: https://deep-learning-study-room.vercel.app/read/cn/tee/papers/paper-2023-ai-partial--q2c/

Exact historical variant. Current-syllabus questions solved; excluded topics and source limitations stated.

### Q2(c). Explain methods of framing. What are the advantages of variable-length frames over fixed-length frames? [5 marks]

### Answer

Framing separates a continuous bit stream into data-link units so the receiver knows where each frame begins and ends.

| Method | Operation | Key issue |
| --- | --- | --- |
| Fixed size | Every N bytes forms one frame | No delimiter needed, but padding may waste capacity |
| Length/character count | Header gives frame length | A damaged count can lose synchronization |
| Byte stuffing | Flag bytes delimit frames; escape any flag/escape inside payload | Receiver removes inserted escape bytes |
| Bit stuffing | Flag01111110; insert0 after five consecutive data1s | Receiver removes the stuffed0 |
| Coding violation | Reserve physical symbols unavailable to data | Depends on the line code |

Variable-length frames fit different packet sizes, reducing padding and often using bandwidth efficiently. They need boundary/length handling and variable buffering; fixed-size frames give simple predictable processing. Example: a20-byte payload need not occupy an entire500-byte fixed frame when a suitable short variable frame is allowed.