Re: hotmail not dealing with ECN

Rogier Wolff
2001-01-27T10:00:36Z

H. Peter Anvin wrote:
> "David S. Miller" wrote:
> >
> > H. Peter Anvin writes:
> > > Last I communicated with them, I looked for a reference like that in the
> > > standards RFCs so I could quote chapter and verse at the Hotmail people,
> > > but I couldn't find it.
> >
> > RFC793, where is lists the unused flag bits as "reserved".
> > That is pretty clear to me. It just has to say that
> > they are reserved, and that is what it does.
> >
>
> Is the definition of "reserved" defined anywhere? In a lot of specs,
> "reserved" means MBZ.

MBZ? Must Be Zero?

Reserved means MBZ on things you generate, to guarantee you'll get
expected behaviour from the other side. But in no circumstance should
a reserved bit being non-zero confuse you. They should be
ignored. That leads to the "new" implementations knowing what the old
implementations will do.

Roger.

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