Internet Protocol Version 6 (IPv6)

Last Modified: November 17, 2007

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IPv6 - Terminology

Node - A device that implements IPv6.

Router - A node that forwards IPv6 packets not explicitly addressed to itself.

Host - Any node that is not a router.

Upper layer - A protocol layer immediately above IPv6. Examples are transport protocols such as TCP and UDP, control protocols such as ICMP, routing protocols such as OSPF, and internet or lower-layer protocols being "tunneled" over (i.e., encapsulated in) IPv6 such as IPX, AppleTalk, or IPv6 itself.

Link - A communication facility or medium over which nodes can communicate at the link layer, i.e., the layer immediately below IPv6. Examples are Ethernets (simple or bridged); PPP links; X.25, Frame Relay, or ATM networks; and internet (or higher) layer "tunnels", such as tunnels over IPv4 or IPv6 itself.

Neighbors - Nodes attached to the same link.

Interface - A node's attachment to a link.

Address - An IPv6-layer identifier for an interface or a set of interfaces.

Packet - An IPv6 header plus payload.

Link MTU - The maximum transmission unit, i.e., maximum packet size in octets, that can be conveyed over a link.

Path MTU - The minimum link MTU of all the links in a path between a source node and a destination node.

IPv6 - Addressing

Unicast

An identifier for a single interface. A packet sent to a unicast address is delivered to the interface identified by that address.

Anycast

An identifier for a set of interfaces (typically belonging to different nodes). A packet sent to an anycast address is delivered to one of the interfaces identified by that address (the "nearest" one, according to the routing protocols' measure of distance).

Multicast

An identifier for a set of interfaces (typically belonging to different nodes). A packet sent to a multicast address is delivered to all interfaces identified by that address.

IPv6 - Transition Mechanisms

Dual Stacks

To allow IPv4 and IPv6 to co-exist in the same devices and networks.

Tunnels

Tunnels encapsulate IPv6 traffic within IPv4 packets and are primarily for communication between isolated IPv6 sites or connection to remote IPv6 networks over an IPv4 backbone.

+ Manually configured tunnel (RFC 2893)

+ GRE (RFC 2473)

+ Tunnel brokers (RFC 3053)

+ 6to4 (RFC 3056)

+ ISATAP (RFC 4214 )

+ 6over4 (RFC 2529)

+ Teredo (RFC 4380 )

Translators

To allow IPv6 only devices to communicate with IPv4 only devices.

Network Level translators

+ SIIT (RFC 2765)

+ NAT-PT (RFC 2766)

+ Bump in the stack - BIS (RFC 2767)

Transport Level Translators

+ Transport Relay Translator TRT (RFC 3142)

Application Level Translators

+ Bump in the API - BIA (RFC 3338)

+ SOCKS64 (RFC 3089)

Deploying IPv6 over dedicated data links

This technique enables IPv6 domains to communicate by using the same layer 2 infrastructure used for IPv4 but with IPv6 using separate frame relay or ATM PVCs, separate optical links or lambdas in DWDM.

Deploying IPv6 over MPLS backbones

This technique allows IPv6 domains to communicate with each other, but over an IPv4 MPLS backbone without modifying the core infrastructure.

+ IPv6 tunnels on CE routers

+ Layer 2 circuit transport over MPLS

+ IPv6 on PE routers (6PE)

+ Adding IPv6 MPLS VPNs to 6PE (6VPE)

+ Native IPv6 MPLS based backbone