IPv6

Basics

Global Unicast Address:

  • Globally unique and routable

  • Equivalent to Public IPv4 Address

  • Begins with hex 2 or 3

  • can be source or destination

  • Is not a mandatory address

  • example 2001:db8:cafe:1::100

Link-Local Unicast Address:

  • Local to a logical network subnet (connected to one ethernet interface)

  • Not routable beyond the local subnet

  • Every Device must have a link local per network interface based on its MAC address

  • begin with fe80::

Unspecified Address:

  • all zeros [::] which is equivalent to IPv4 0.0.0.0

  • Can only be set as a source address

  • Can be used by a process to bind to all interfaces

  • Can be used during Neighbour Discovery before setting up a Unicast Address

  • Is never routed / forwarded by a router

Solicited-Node Multicast Address

  • Similar to IPv4 Broadcast Address: 192.168.0.0\24 broadcast 192.168.0.255

  • Used by ICMPv6 NDP (Neighbour Discovery Protocol) to determine the MAC address of a host on a local Network

  • Only Valid as a destination Address, and never routed off the link or the subnet

  • Starts with ff02::1:ff00:0/104

Interface ID of a Node or Device

Equivalent to the host Portion of IPv4. A Node or a Device can have multiple Interfaces, and A Single Interface can have Multiple IPv6 addresses

Prefix and Prefix Length

A prefix Is the network Portion of an IPv6 address, size is from /0 to /128 If the Prefix Length is /64 then the Interface ID length is /64 If the Prefix Length is /70 then the interface ID Length is /48

Neighbour Discovery Protocol (NDP) Over ICMPv6

NDP is used for on-link (same subnet) device discovery and messaging

Includes 5 Message types

  • Router Solicitation (RS)

  • Router Advertisement (RA)

  • Neighbour Solicitation (NS)

  • Neighbour Advertisement (NA)

  • Redirect Message

Dynamic Address Allocation

Stateless Address Autoconfiguration (SLAAC)

  • Uses all the information in the RA for its addressing needs

  • RA includes Prefix Length and Prefix, and used to create a global Unicast Address

  • The device will use the Source IPv6 Address in the RA as its default gateway

SLAAC + Stateless DHCPv6

  • Similar to SLAAC

  • The device obtains the default Gateway from the RA

  • Addtionally the RA Suggests to the device to contact a DHCPv6 Server for Extra Information

  • Extra info includes DNS Server, among other info

  • Stateless DHCPv6 does not provide nor maintain a table of Unicast Addresses

Stateful DHCPv6

  • the RA Suggests to the device to obtain all IPv6 Addressing info from a Stateful DHCPv6 server

  • The Device obtains the default gateway from the RA

  • The device obtains A global Unicast Address, and DNS Servers from the Stateful DHCPv6 Server

  • Similar to DHCPv4