RE: Running code (Was: I-D Action: draft-ietf-6man-ipv6only-flag-03.txt)

["Manfredi (US), Albert E" <[e-mail]>]

-----Original Message-----
From: Brian E Carpenter <[e-mail]> 

> It adds the *intention* of the network manager that there should be no
IPv4 traffic on the link. Of course, a host can decide to ignore that
intention, and protocol police in the form of layer 2 filters may enforce
the intention.

But Brian, the network manager (usually, often) has no business making such decisions, other than for the services net admin provides. *Especially* if the protocol police filters at layer 2, the network user should be legally and ethically able to bring his own IPv4 peripherals, and switch and/or IPv4 router, and have them work. With no negative impact to anyone else.

We already know that the flag is set individually, at each router. You may have three routers that have the flag set, and one that does not. So this says quite clearly, do not bother trying to route IPv4 packets through the routers with flag set. It does not say that the net manager doesn’t want IPv4 traffic in the link. Push comes to shove, the flag means only, this router won’t transfer IPv4 packets.

If there's any intention for this flag to be misconstrued by some equipment vendors, creating a clever puzzle to be solved by perfectly legitimate users, every time they need to add equipment, then I'd say, let's avoid that. No?

> Personally, if I was in a position to write the heuristic that a host
uses, I would use this flag as a heavily weighted input that would
either prevent any IPv4 activity whatever, or increase the backoff
timers to a very large value, since it's a clear signal that, for example,
mDNS over IPv4 is simply not available.

Maybe so. Or maybe, after spending time writing the new logic, the equipment designer writing the heuristics will determine they can mostly ignore the flag? That's always been my question, in this thread.

Bert