Re: Source address selection in IPv6 multihomed multi-addressed sites

[Erik Nordmark <Erik.Nordmark@sun.com>]

> So it is assumed that ISPs will filter their customer's traffic and 
> only let packets with valid source addresses through. This gives us a 
> range of options:
> 
> 1. do nothing (what we do today) -> traffic will regularly not make it 
> through -> a lot of unhappiness
> 2. ask ISP to let traffic through -> ISP may say no -> much unhappiness 
> or upstream ISP filters -> also unhappiness
> 3. figure out the right source address (sort of happens today 
> automatically sometimes) -> traffic will get through, but if the 
> destination is rerouted over the other link the session breaks -> still 
> considerable unhappiness
> 4. do source address dependent routing -> easy when only one box does 
> this, harder in sites where there is internal routing, still problems 
> with routing changes

And 5: have the site border router rewrite the source locator.
This assumes that id/locators are split, that the rewriting doesn't
effect "legacy packets" (without the id/loc split), and that the system
for securely verifying the id/locator relationship can handle
such rewriting.

Thus understanding the tradeoff between source locator rewriting and other
parts of the system is important.

  Erik