# IPv6 and packet lengths

Subject: Computer Networks

Exam: M2

Reader: https://deep-learning-study-room.vercel.app/cn/#m2/formulas/formulas/ipv6

Canonical: https://deep-learning-study-room.vercel.app/read/cn/m2/formulas/formulas--ipv6/

M2 · symbols explained; worked examples linked below

Supporting formula collection. Use the compact TEE formula sheet first; the full calculation set below is not an observed-paper requirement.



$$
\text{omitted groups}=8-\text{visible groups}
$$



Count every written group, including a written 0.



$$
\mathrm{IPv6\ total}=40+\mathrm{payload\ length}
$$



Payload includes extension headers, excludes the base 40 bytes.



$$
\mathrm{IPv4\ header\ bytes}=4\,\mathrm{IHL}
$$



IHL is in 32-bit words.



$$
\mathrm{IPv4\ payload}=\mathrm{Total\ Length}-4\,\mathrm{IHL}
$$



IPv4 Total Length includes the IPv4 header.

## Learn it with complete solutions

[Four IPv6 expansions](https://deep-learning-study-room.vercel.app/read/cn/m2/read/ipv6--expand-1/)