Re: TOS field in IP packet

Bill Barns (
Tue, 6 Sep 88 14:49:04 EDT

I don't recall seeing any response to this, and the subject is of current
interest to me. I am working up an analysis of options for dealing with
certain kinds of potential "requirements" for network usage accounting
and one of the approaches to be considered for internetwork reverse
charging might involve using one of the two reserved bits to which you
refer. I believe they are still officially reserved and supposed to be
0. I have contributed to appropriate people the thought that it would
be a good thing for a TCP/IP implementor to make provision for setting
and reading the two reserved bits even before any meaning is defined for
them. It's just as important to have it be settable at TCP/application
interface level as at IP/transport interface. One should also consider
the possibility that the reserved TOS bits may require a negotiation
analogous to precedence.

If anyone out there is working in the same problem domain I am, or can
point me to such people, please drop me a note. I am especially
interested in finding out about anything in the OSI arena subsequent to
the Accounting Management Service Definition, TC97/SC21 N981 (alias
TC97/SC21/WG4 N117). I've already queried the ISO mailing list but no
news so far...

Bill Barns / MITRE / / (703) 883-6832

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