Default Address Selection for Internet Protocol version 6 (IPv6)

Abstract

This document describes two algorithms, for source address selection and for destination address selection. The algorithms specify default behavior for all Internet Protocol version 6 (IPv6) implementations. They do not override choices made by applications or upper-layer protocols, nor do they preclude the development of more advanced mechanisms for address selection. The two algorithms share a common context, including an optional mechanism for allowing administrators to provide policy that can override the default behavior. In dual stack implementations, the destination address selection algorithm can consider both IPv4 and IPv6 addressesdepending on the available source addresses, the algorithm might prefer IPv6 addresses over IPv4 addresses, or vice-versa.

An Empirical Evaluation of a Shim6 Implementation

“…At present, the default IPv6 address selection algorithm [10] defines how the address pair for a communication session is selected, this address pair does not change for the duration of the session. Shim6 offers the ability to change the address pair used (and thus the path) during the session, transparent to the application.…”

An incremental approach to IPv6 multihoming

“…If the failure arises in one of the providers or links close to Host2 (for example in ProviderK), and Host1 starts the communication, it can happen the following: Host1 accesses DNS to obtain the addresses of Host2. With the received addresses, the Address Selection procedure [7] selects a hsource address, destination addressi pair. Suppose that the destination address belongs to the address range delegated to the network of Host2 by ProviderK.…”

“…It becomes relevant then to understand how the address selection is performed. Current default address selection algorithms are defined in RFC 3484 [7] and they define a set of rules and data structures that allow the host to select among the multiple addresses available. In particular, hosts have a policy table that provides the means to express policy considerations when selecting among multiple addresses.…”

“…The parameters included in a NAROS request are at least the destination address of the correspondent and the source addresses currently allocated to the client. The NAROS server should only be contacted when the default source address selection procedure [7] cannot select the source address.…”

“…The regular address selection process for IPv6 specified by RFC 3484 [7] is used by HostX to select one of the addresses of HostY (PYJ:IYJ) as destination address for the outgoing packets, and one of its own address (PXK:IXK) as source address. These addresses selected at the beginning of the communication will also be used as endpoint identifiers for transport and application layers when required.…”