Routing Theory
IPv6 Addressing
IPv6 Addressing
  • Introduction
  • Addresses
  • Addressing Model
    • GUA
    • Link Local
    • Site Local
    • ULA
    • Anycast
    • Multicast
      • Solicited Node Multicast Address
  • Subnetting
    • Example
  • The last 64 bits
  • Routing Protocols
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  1. Addressing Model

GUA

Global Unicast Addresses (GUA)

PreviousAddressing ModelNextLink Local

Last updated 1 year ago

Addresses have scope.

Global Unicast Addresses (GUA) are similar to IPv4 public unicast addresses.

At the moment, 2001::/16 is used for global unicast, pretty much the entire IPv6 Internet!

This network space is distributed amongst the regional internet registries (RIRs) and local internet registries (LIRs) and then to ISPs.

For example, the ISP for Irish research and education is HEANet and they have 2001:770::/32.

Clients are typically allocated /48 prefixes and ATU Letterkenny has 2001:770:3c::/48

If all subnets are /64, this leaves every client with 2^16 or 65,536 subnets.

To make routing simple and hierarchical, this will normally be allocated as something like;

  • Site (4-bits)

  • Building (4-bits)

  • Subnet (8-bits)