Owen DeLong wrote:
The number of routing table entries is growing exponentially, not because of increase of the number of ISPs, but because of multihoming.
Again, wrong. The number is growing exponentially primarily because of the fragmentation that comes from recycling addresses.
Such fragmentation only occurs when address ranges are rent to others for multihoming but later recycled for internal use, which means it is caused by multihoming. Anyway, such cases are quite unlikely and negligible.
There are actually ways to do IPv6 multihoming that don’t require using the same prefix with both providers.
That's what I proposed 20 years ago both with IPv4 and IPv6 in: https://tools.ietf.org/id/draft-ohta-e2e-multihoming-02.txt
Yes, there are tradeoffs, but these mechanisms aren't even practical in IPv4,
Wrong. As is specified by rfc2821: When the lookup succeeds, the mapping can result in a list of alternative delivery addresses rather than a single address, because of multiple MX records, multihoming, or both. To provide reliable mail transmission, the SMTP client MUST be able to try (and retry) each of the relevant addresses in this list in order, until a delivery attempt succeeds. However, there MAY also be a configurable the idea of end to end multihoming is widely deployed by SMTP at the application layer, though wider deployment require TCP modification as I wrote in my draft. Similar specification is also found in section 7.2 of rfc1035.
but have been sufficiently widely implemented in IPv6 to say that they are viable in some cases.
You are just wrong. IP layer has very little to do with it. Masataka Ohta PS LISP is garbage.