Computer Networks · TEE · practice

IPv6 packet length · example 3

IPv6: addresses and packet format · optional practice

Optional extension · no matching calculation in the two supplied papers

Optional worked extension. This calculation format was not found in the supplied December 2025 final or February 2026 re-exam. The numbers and practice marks are authored. Study the core concept and actual-paper questions first; this is extra explanation, not a TEE prediction.

Practice question. An IPv6 packet has a 40-byte base header, 40 bytes of extension headers and 500 bytes of upper-layer content. Find its Payload Length field value and total packet length. [3 practice marks]

Answer

Given

Base=40 bytes; extensions=40 bytes; upper-layer content=500 bytes. Ordinary non-jumbo packet.

To find

Payload Length and total bytes.

Formula and why

P=E+D,\qquad T=40+P

Payload begins immediately after the IPv6 base header. Extensions are part of that payload.

Step-by-step solution

Step 1. Calculate payload

P=40+500=540 bytes.

Step 2. Add the base header

T=40+540=580 bytes.

Step 3. Identify the stored field

The Payload Length field stores 540, not 580.

Final answer: Payload Length=540; total=580 bytes.