Re: [v6ops] Windows 10 doesn't honour 'M' flag in RA

[Bob Hinden <[e-mail]>]

James,

> On Dec 13, 2017, at 12:27 PM, james woodyatt <[e-mail]> wrote:
> 
> On Dec 13, 2017, at 11:34, Simon Hobson <[e-mail]> wrote:
>> Brian E Carpenter <[e-mail]> wrote:
>> 
>>> Well, the "Note:" does leave an open question. How does the person (or
>>> automaton) configuring the router that sends the RA know that no
>>> information is available via DHCPv6? It is entirely possible that
>>> DHCPv6 is available on another box, and the person configuring the
>>> the router doesn't know it. So these flags are intrinsically unreliable
>>> and can only be hints; it's *necessary* that hosts are allowed to
>>> ignore them and look for DHCPv6 anyway.
>> 
>> I keep hearing this argument time and time again, but cannot reconcile it with any professionally managed network. Are there really professionally managed networks where the guys responsible for the routers (intrinsically tied in with the network config) don't talk to the guys running DHCP servers (intrinsically tied in with the network config) ?
>> Put another way, are there really networks where two different groups "do their own thing" without agreeing between themselves how the network is supposed to work ?
> 
> Put another way, "are there really professionally managed networks?”
> 
> Worth noting: the point is that the “Note:” in RFC 4861 cited previously in the thread asserts that M=0&O=0 is a signal to all hosts on the link that “no information is available via DHCPv6,” which is really only true while *all* the routers on the link are consistently sending that signal. It stops being true as soon as one or more of the routers on the link contradict the signal, and it continues to not be true until all the contradicting routers expire their valid lifetimes. On a “professionally managed network,” there might never be any contradicting routers on the link at any time, and in that case the Note correctly describes how the protocol works. In other cases, however, it remains a little less than clear.
> 
> So, I ask again: are there really professionally managed networks?

Yes.  The common definition of professional is that you get paid to do a job.  How well you do it is another matter :-)

To you point, I think there are networks where all of the routers are configured correctly.

Bob