Joel jaeggli wrote:
That's a fairly simplistic version of why shim6 failed. A better reason (appart from the fact the building an upper layer overlay of the whole internet on an ip protocol that's largely unedeployed was hard) is that
Shim6 failed mostly because of its complexity. It is complex mostly because its architecture is broken, trying to hide existence of shim6 from applications (the end systems within end hosts), which is against the end to end principle and impossible, only to make application modifications even more complicated. Other added features makes shim6 even worse.
it leaves the destination unable to perform traffic engineering. That fundementaly is the business we're in when advertising prefixes to more than one provider, ingress path selection.
That's not a inherent problem of architectures with multiple addresses. Destination hosts can listen to advertisements of destination network administrators and suggest source hosts which prefixes are preferred by the administrators. That is the end to end way of destination traffic engineering without bloating routing table entries. Masataka Ohta