IPv6 Addressing

IPv6 Addressing

• localhost (loopback) address is reduced to ::1, and the IPv6 unspecified address is reduced to ::.
• IPv4-mapped and IPv4-compatible IPv6 addresses are written in a special notation, combining IPv4 dot-decimal notation and IPv6 format.

Parts of IPv6 Address & Address Allocation

• Only one eighth of the total address space is currently allocated for use on the Internet (2000::/3).
• The address space is assigned to RIRs in large blocks of /23 up to /12, which are then divided into smaller blocks for local Internet registries and eventually to end users.
• Each RIR can divide each of its multiple /23 blocks into 512 /32 blocks, typically one for each ISP.
• An ISP can divide its /32 block into 65536 /48 blocks, typically one for each customer.
• Customers can create 65536 /64 networks from their assigned /48 block, each having 2^64 (18,446,744,073,709,551,616) addresses.

Advantages of IPv6

• More efficient address space allocation
• End-to-end addressing without NAT
• Fragmentation only at the source host
• Routers do not calculate header checksum
• No broadcast, uses multicast instead
• Built-in security mechanisms
• Auto-configuration of addresses
• Headers are modular/extensible

IPv6 Protocols

• The primary purpose of the core IPv6 protocol is to define a packet concept, addresses, and the role of hosts and routers.
• IPv6 supports routing protocols such as RIPng, OSPFv3, EIGRP for IPv6, IS-IS for IPv6, and MP-BGP4.

ICMP Upgraded to ICMP Version 6

• ICMP has been changed to support IPv6.
• A host sends a link-local multicast (broadcast) request for its configuration parameters when first connected to a network.
• Routers respond to such a request with a router advertisement packet containing network-layer configuration parameters.

Multicast

• Multicast is part of the base protocol suite in IPv6.
• Most environments do not currently have their network infrastructures configured to route multicast; only link-scoped multicast works.

Jumbograms

• IPv6 has optional support for packets over 64 KB of payload, referred to as jumbograms, which can be as large as 4 GB.
• The use of jumbograms may improve performance over high-MTU networks.

Network-Layer Security

• IPsec, the protocol for IP network-layer encryption and authentication, is an integral part of the base protocol suite in IPv6.
• IPsec is not widely deployed except for securing traffic between IPv6 BGP routers.

Mobility

• Mobile IPv6 (MIPv6) avoids triangular routing and is therefore as efficient as normal IPv6.

Unique Local Addresses (FC00::/7)

• These addresses are intended for non-routing purposes over the Internet and are nearly globally unique.
• Unique local addresses were designed to replace site-local addresses.

Multicast (FF00::/8)

• Packets addressed to a multicast address are delivered to all interfaces tuned into the multicast address.
• Multicast addresses always start with FF.

Anycast

• An anycast address identifies multiple interfaces on multiple devices.
• The anycast packet is delivered to only one device, the closest one found in terms of routing distance.
• Anycast addresses are typically configured on routers, never hosts, and a source address could never be an anycast address.

Special IPv6 Addresses

• :: is the equivalent of IPv4's 0.0.0.0 and is typically the source address of a host before the host receives an IP address.
• ::1 is the equivalent of 127.0.0.1 in IPv4.
• 2000::/3 is the global unicast address range.
• FC00::/7 is the unique local unicast range.
• FE80::/10 is the link-local unicast range.
• FF00::/8 is the multicast range.

IPv6 Header Structure

• The Next Header field specifies the transport layer protocol used by a packet's payload.
• In the presence of options, the Next Header field specifies the presence of an extra options header, which then follows the IPv6 header.
• The payload's protocol itself is specified in a field of the options header.

Transition Mechanisms

• Transition mechanisms are needed to enable IPv6-only hosts to reach IPv4 services and to allow isolated IPv6 hosts and networks to reach the IPv6 Internet over the IPv4 infrastructure.
• Dual Stack: a network stack that supports both IPv4 and IPv6 while sharing most of the code.
• Tunneling: a technique that consists in encapsulating IPv6 packets within IPv4, in effect using IPv4 as a link layer for IPv6.

IPv6 Address Assignments Options

• Manual Configuration: network administrator can manually configure IPv6 address to routers interfaces.
• Stateless Autoconfiguration: a host can generate its own addresses using local information and non-local information advertised by routers.
• Modified EUI-64 (Extended Unique ID-64): a 64-bit interface identifier derived from a 48-bit MAC address.

Tunneling Techniques

• Automatic Tunneling: a technique where the tunnel endpoints are automatically determined by the routing infrastructure.
• 6to4 Tunneling: a recommended technique for automatic tunneling that uses protocol 41 encapsulation.
• Teredo: an automatic tunneling technique that uses UDP encapsulation.
• Configured Tunneling: a technique where the tunnel endpoints are configured explicitly, either by a human operator or by an automatic service known as a Tunnel Broker.
• Proxying and Translation: when an IPv6-only host needs to access an IPv4-only service, some form of translation is necessary, such as the use of a dual-stack application-layer proxy.

Special IPv6 Addresses

• :: (0:0:0:0:0:0:0:0): the equivalent of IPv4's 0.0.0.0, typically the source address of a host before the host receives an IP address.
• ::1 (0:0:0:0:0:0:0:1): the equivalent of 127.0.0.1 in IPv4.
• 2000::/3: the global unicast address range.
• FC00::/7: the unique local unicast range.
• FE80::/10: the link-local unicast range.
• FF00::/8: the multicast range.
• 3FFF:FFFF::/32: reserved for examples and documentation.
• 2001:0DB8::/32: also reserved for examples and documentation.

Other Features of IPv6

• Multicast: part of the base protocol suite in IPv6, in opposition to IPv4, where multicast is optional.
• Jumbograms: optional support for packets over 64 KB of payload, which can be as large as 4 GB.
• Network-Layer Security: IPsec, the protocol for IP network-layer encryption and authentication, is an integral part of the base protocol suite in IPv6.
• Mobility: Mobile IPv6 (MIPv6) avoids triangular routing and is therefore as efficient as normal IPv6.