This post is a work in progress and general reference guide to refresh my poor memory when needed …
SHIM6 (RFC5533)
The purpose of the SHIM6 protocol is to provide a failover mechanism for hosts where they are connected to the Internet with multiple provider provided IPv6 address ranges in a multihomed configuration. It does this by inserting a unique identifier between the IP address and the upper layer protocols. The upperlayer protocols therefore do not use the assigned IP address for communication, rather the unique identifier. The host is therefore able to switch IP addresses (in the event of a failover) and the upper layer protocols should be none the wiser. To accomplish failover, the REAP protocol (RFC5534) is used to identify if the link is down and what the available IP address of the remote peer is.
Mobile IPv6 (RFC6275)
Titled “Mobility Support in IPv6”, this RFC defines the mechanism through which a host can move from one network to another without losing the session with a remote peer. It does this through the concept of a home network where a home router will forward the packets from the peer to the newly assigned IP address of the host on the new network. Various mechanisms exist for optimizing the handover and traffic flows so that tromboning and other such issues do not occur.