IPv6 Addressing Details LAC NIC VII October 26, 2004 Wilfried

topics Header (format, extension header) AddresstypesConfiguration Scope, lifetime

Header fixed-length 40 byte header checksum removed no options in base header new flow label field (use is currently not defined) faster packet processing (with hardware support) options in flexible and extensible extension headers (can be transparent for transit nodes)

Extension Headers hop-by-hop (various, e.g. discard packet w/o ICMP) routing (address list source routing) fragment (fragmentation only done by source) destination options (various, e.g. discard packet w/o ICMP) authentication (integrity and data origin auth.) encapsulating security payload (confidentiality)

Addresstypes unicast (identifier for single interface, packet is sent to interface identified by that address) anycast (identifier for a set of interfaces, packet is sent to one of the interfaces identified by that address (the 'nearest' one)) multicast (identifier for a set of interfaces, packet is sent to all interfaces identified by that address)

Ext. Representation / Format x:x:x:x:x:x:x:x x is 16bit hex-value leading zeros are not necessary & series of zeros can be compressed 2058:0000:0000:000b:0800:ac23:0001 = 2058::b:800:ac23:1 prefix length is written in CIDR notation 3ffe:8034:80:1:2a0:24ff:fe9d:5094/64

Unicast Addresses unspecified (::/128) [ no IPv4 equivalent ] loopback (::1/128) [similar to in IPv4] link-local (prefix fe80::/10 + interface identifier) site local (prefix fec0::/10 + interface identifier) [killed] global (e.g. prefix 2001:600::/23 for RIPE region) IPv4-compatible address (:: ) IPv4-mapped address (::ffff: ) IPv6 addr. cont. encoded OSI NSAP addr.

Interface Identifier used to identify interfaces on a link has to be unique on that link has to be unique on that link 64 bits long, modified EUI-64 format created from-) IEEE EUI-64 identifier -) IEEE bit MAC -) any other link identifier -) manually chosen identifier created from-) IEEE EUI-64 identifier -) IEEE bit MAC -) any other link identifier -) manually chosen identifier uniqueness can be independent of address ==> or picked at random to protect privacy!

Anycast Addresses allocated from the unicast address space nodes must be explicitly configured host-routes are needed !!! most likely NO global anycast sets status: no anycast for hosts, only for routers: subnet-router anycast address same as unicast address, but interface identifier set to zero

Multicast Addresses ff00::/8 flags: 3 high-order reserved, permanently/ non-permanently scope: various scopes (e.g. link-local, org-local, global) group id: identifies multicast-group some multicast addresses are reserved e.g.:all nodes addr (ff0x::1) all routers addr (ff0x::2) solicited-node address routers must not forward any multicast packet beyond the scope indicated by the scope field

Lifetime / Scope lifetime valid preferred valid deprecated - not to be used to initiate new communication invalid - must not be used (neither source nor destination) scope link (uni-, multicast) link (uni-, multicast) subnet (multicast) subnet (multicast) site (uni-, multicast) site (uni-, multicast) admin (multicast) admin (multicast) global (uni-, multicast) global (uni-, multicast) organization (multicast) organization (multicast)