https://ttl-expired.net/tags/ipv6/ Recent content in Ipv6 on TTL Expired Hugo en-us Wed, 15 Apr 2026 00:00:00 +0000 https://ttl-expired.net/docs/ipv6/ Wed, 15 Apr 2026 00:00:00 +0000 https://ttl-expired.net/docs/ipv6/ <h2 id="ipv6">IPv6</h2> <p>IPv6 was designed to solve IPv4 address exhaustion while simplifying the protocol. The header is fixed-length and streamlined, broadcast is eliminated in favor of multicast, and address configuration can be fully automatic. For service providers, the most exam-relevant areas are address types, NDP, autoconfiguration, and how routing protocols (OSPF, IS-IS) extend to support IPv6.</p> <hr> <h3 id="ipv4-vs-ipv6-key-differences">IPv4 vs IPv6 Key Differences</h3> <table> <thead> <tr> <th>Feature</th> <th>IPv4</th> <th>IPv6</th> </tr> </thead> <tbody> <tr> <td>Address size</td> <td>32 bits</td> <td>128 bits</td> </tr> <tr> <td>Header size</td> <td>Variable (20–60 bytes)</td> <td>Fixed 40 bytes</td> </tr> <tr> <td>Header checksum</td> <td>Yes</td> <td>No (relies on L4)</td> </tr> <tr> <td>Fragmentation</td> <td>Routers and source</td> <td>Source only</td> </tr> <tr> <td>Broadcast</td> <td>Yes</td> <td>No — replaced by multicast</td> </tr> <tr> <td>Address resolution</td> <td>ARP</td> <td>NDP (ICMPv6)</td> </tr> <tr> <td>Autoconfiguration</td> <td>DHCP only</td> <td>SLAAC + DHCPv6</td> </tr> <tr> <td>IPsec</td> <td>Optional</td> <td>Built into extension header framework</td> </tr> </tbody> </table> <hr> <h3 id="ipv6-header">IPv6 Header</h3> <p>The base IPv6 header is always exactly <strong>40 bytes</strong>. It is simpler than IPv4 — no checksum, no options field, and no fragmentation fields (those are handled by extension headers when needed).</p>