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From: DCP@QUABBIN.SCRC.Symbolics.COM (David C. Plummer)
Newsgroups: mod.protocols.tcp-ip
Subject: Re: IEEE and Ethernet
Message-ID: <860624225230.7.DCP@FIREBIRD.SCRC.Symbolics.COM>
Date: Tue, 24-Jun-86 22:52:00 EDT
Article-I.D.: FIREBIRD.860624225230.7.DCP
Posted: Tue Jun 24 22:52:00 1986
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    Date: Tue, 24 Jun 86 13:34:05 PDT
    From: Murray.pa@Xerox.COM

    "I assume this applies to the protocol field as well?"

    The IEEE doesn't think anybody needs a protocol field. They use that
    word for the packet length.  Thus I doubt very much if they are
    interested in assigning values. I don't know for sure though.

    Most of the existing protocol values were "grandfathered" in because
    they are invalid lengths. The official 802 position is that they don't
    care what consenting adults do with packets having invalid lengths.
    (There is probably a footnote along that line in the specs.) 

    The only protocol field values that weren't big/lucky enough to get
    grandfathered this way are used for Pup. A pair of alternates have been
    assigned. The switchover is painful. Most places have ignored it. I
    think the Ethernet driver for the latest VMS now rejects old Pups. That
    doesn't make the switchover any easier, but it might make it happen
    sooner.

OK, my ignorance is showing.  Given that what used to be the protocol
field is now the length, how does one determine what layer (protocol)
the packet is really for?  I assume there is still a 16 bit field
SOMEPLACE.  Who assigns those numbers?