Site Multihoming by IPv6 Intermediation
The SHIM6 protocol is an Internet Layer shim defined in RFC 5533.
Architecture
The SHIM6 architecture defines SHIM6 Failure Detection and Locator Pair Exploration functions. The first is used to detect outages through the path defined by the current locator pair for a communication. To achieve this, hints provided by upper protocols such as TCP are used, or specific SHIM6 packet probes. The second function is used to determine valid locator pairs that could be used when an outage is detected.
The ability to change locators while a communication is being held introduces security problems, so mechanisms based on applying cryptography to the address generation process (Cryptographically Generated Addresses, CGA), or on bounding the addresses to the prefixes assigned to a host through a hash (Hash-based addresses, HBA) have been defined. These approaches are not feasible for IPv4 because of the short address length (32 bits).
An implementation of shim6 in the Linux kernel called LinShim6 is now available.
See also
References
- C. de Launois and M. Bagnulo. The Paths towards IPv6 Multihoming. IEEE Communications Surveys and Tutorials, 8(2), 2006