Re: [RRG] Six/One: A (Different) Solution for Routing and Addressing in IPv6

[Christian Vogt <christian.vogt@nomadiclab.com>]

> Seems to me you need to decide: either the user/host gets to decide,
> or the middle box does.  You can't have it both ways.  Which is it?

Tony,

please let me know if the explanation below makes things clear.  This is
an important aspect of Six/One.

By sending a packet with an IP source address with provider P1's routing
prefix, a host tells the edge network:  "P1 is the provider I would like
to have my packets go through."

Then it is up to the edge network's policy:

- If network resources and traffic engineering strategies permit, the
edge network can decide:  "OK, we will route the packet to provider P1
as suggested by the host."

- Otherwise, the edge network will say:  "No, we will route the packet
through a different provider P2.  So let's rewrite the routing prefix in
the packet's IP source address so that it matches provider P2."

In other words, hosts can /suggest/ a particular provider, but the edge
network finally decides and /selects/ the provider.

Since hosts adopt a new IP address after a rewrite, network-enforced
provider changes (i.e., path changes) are visible to both hosts of a
connection.  Hosts can then do whatever is necessary to adapt to the
path change efficiently (e.g., by resetting TCP RTT estimations and
triggering Slow Start mode).

Ciao,
- Christian




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