Re: Multihoming by IP Layer Address Rewriting (MILAR)

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

On Tue, 18 Sep 2001, Mattias Pettersson wrote:

> > Having a connection setup attempt fail so it has to be retried at the
> > application level is not good enough.

> I agree that the user can't accept that. But what do other proposals do
> (we are talking about connection setup)?

> Send TCP SYN to multiple peer addresses? The peer would ignore multiple
> attempts. I think that was mentioned before.

> We need mechanisms that will provide the first address of the peer that
> has a high probability of being reachable.

Since replicating this information regardless of whether it will be used
or not (such as is current practice with BGP) does not scale, the only
solution to this is to have the host try. Optionally, the information
gathered this way could be stored/shared for further use.

> I don't know if DNS can reflect that fast enough.
> The draft mentions SIP, and such mechanisms
> that are based on registering are good if the peer knows which of its
> addresses are reachable and which are not.

Which is certainly not something we can rely on...

So this means either pinging the host to find a working address before the
TCP setup, or just trying the TCP setup and retry it transparently if it
fails or takes too long.

> The draft assumes that we can't read too much stability into the IP
> addresses of a node. Addresses come and go. As long as you have a
> session established between two nodes then they can inform each other of
> address changes.

But I'm not sure if mobile IP does in a way that is robust enough for our
purposes.

Iljitsch van Beijnum