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Common IPv6 Issues. Margaret Wasserman INT Area Meeting IETF65, Dallas. Motivation. Many documents come to the IESG with IPv6-related issues Mistakes in the use of IPv6 Failure to note differences from IPv4 Ignoring IPv6 entirely, without explanation
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Common IPv6 Issues Margaret Wasserman INT Area Meeting IETF65, Dallas
Motivation • Many documents come to the IESG with IPv6-related issues • Mistakes in the use of IPv6 • Failure to note differences from IPv4 • Ignoring IPv6 entirely, without explanation • Embarrassing when this happens in INT area documents
Common IPv6 “Gotchas” • Differences in addressing architecture • Fragmentation or MTU-related issues • Neighbor Discovery vs. ARP • IPv6 documentation prefixes
Address Architecture • Not just bigger addresses, a new address architecture… (see RFC 4291) • No IPv6 broadcast address, use All-Nodes Multicast address instead • There is an IPv6 loopback address • 0::1 • IPv6 addresses with embedded IPv4 addresses • Use IPv4-Mapped IPv6 Address, IPv4-compatible address is deprecated • 0::FFFF:10.0.0.1
Scoped Unicast Addressing • IPv6 has concept of scoped unicast addressing • Link-local & global, site-local is deprecated • IPv6 adds support for unique local addresses (ULAs) • Not a direct map to IPv4 net 10 addresses • ULAs are probabilistically unique, so a node can be on more than one local network • Useful for local or private network addressing
MTU and Fragmentation • IPv6 requires lower layers to support an MTU of 1280 bytes (as opposed to 536 in IPv4) • IPv6 routers do not fragment packets • Path MTU discovery is mandatory • All fragmentation happens at the source
ND vs. ARP • IPv6 L2 address resolution is performed using Neighbor Discovery not ARP • ND is ICMP-based • Uses Solicited-Node Multicast addresses • Combines address resolution with host autoconfiguration and reachability detection
IPv6 Documentation Addresses • Global unicast address prefix reserved for documentation purposes (see RFC 3849) • 2001:DB8::/32
IPv6 Required? • There is no BCP or IETF-wide policy that requires IPv6 support in every new protocol defined for IPv4 • Should there be? • However, omitting IPv6 with no explanation is not generally accepted • Adding support for IPv6 usually ranges from trivial to simple • There are some more complicated cases