IPv6

What this topic solves

IPv6 addressing, headers, extension headers, ICMPv6, SLAAC, DHCPv6, routing and dual-stack operation.

Follow state and packet path

Validate prefix, scope, gateway, neighbor resolution, MTU and longest-prefix match. Correct addressing without a return path is still a failure.

Input → classification/state → decision → table → next-hop/output → counters

Design before configuration

• Define the failure domain and expected convergence behavior.
• Document addressing, identifiers, timers, MTU and policy boundaries.
• Prefer explicit, observable state over assumptions.
• Plan rollback and out-of-band access before risky changes.

Commands and verification

Command syntax varies by platform and software release. The examples below come from the existing portal content and must be validated against the target platform documentation before production use.

2001:0db8:0000:0000:0000:0000:0000:0042
→ 2001:db8::42

Regras essenciais:
- zeros à esquerda em cada hexteto podem ser omitidos;
- :: comprime uma sequência contígua de hextetos zero;
- :: só pode aparecer uma vez no endereço;
- forma textual canônica segue recomendações da RFC 5952.

# Linux
ip -6 addr
ip -6 route
ip -6 neigh
ip -6 route get 2001:db8:20::10
ping -6 2001:db8::1
tracepath6 2001:db8:20::10
tcpdump -ni any 'ip6 or icmp6'

# Windows
ipconfig /all
netsh interface ipv6 show addresses
netsh interface ipv6 show neighbors
route print -6
ping -6 2001:db8::1
tracert -6 2001:db8:20::10

# MikroTik RouterOS
/ipv6/address/print detail
/ipv6/neighbor/print
/ipv6/route/print detail

Evidence-driven workflow

1. Define source, destination, time window and exact symptom.
2. Establish the expected healthy state and compare it with the observed state.
3. Inspect counters, tables, logs and packet captures before resets.
4. Test one hypothesis at a time and prefer reversible changes.
5. Repeat the original test after correction and check side effects.

IETF IPv6 RFCs

Use the current standard/RFC and the documentation for the exact software release being operated. Vendor syntax is an implementation detail; protocol behavior should be understood independently.

Prove the behavior in a controlled topology

Build the smallest topology that reproduces the mechanism, capture control and data traffic, introduce one deliberate failure and diagnose it before applying the fix.

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