Identifier/locator recap

[Iljitsch van Beijnum <iljitsch@muada.com>]

On Sun, 16 Mar 2003, Bound, Jim wrote:

> Could you write up your technical idea without a lot of man hours to
> describe and why it solves the multihome problem.

I'm not Tony, but:

Traditional multihoming as is done in IPv4 will not scale.

An alternative is to give each host in a multihomed site an address for
each ISP the site is connected to. When (the link to) one ISP fails, the
communciation is diverted over the other ISP. However, current transport
protocols are unable to jump to new addresses in mid-session. Solution:
separate the identifier and locator functions of the IP address.
Transport protocols then use the identifier, which doesn't change during
the lifetime of the session, while IP uses the locator, which may be
changed at any time in order to route around broken parts of the
network.

A few things that need to be addressed to make this happen:

- Locators must always be present in each packet. But what about the
  identifiers? Do we include them in each packet (= tunneling) or are
  they implied?

- How do we discover identifiers and/or locators?

- How to we authenticate the relationship between locators and
  identifiers?

There is also the question of what makes good identifiers. HIP uses the
fingerprint of a cryptographic key. MHAP uses provider-independent IPv6
addresses that aren't visible in the global routing table. I myself have
suggested to use FQDNs as the first choice.

Note that there seems consensus here that we shouldn't try to revive GSE
or 8+8: some kind of "16+16" would be much easier to deploy.

Iljitsch