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    SubjectRe: Synchronous board drivers
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    <DIV><FONT face=Arial size=2>From: Paul Mackerras &lt;<A
    href=""></A>&gt;<BR><BR>&gt; The
    address and control bytes are really part of the medium-specific<BR>&gt;
    encapsulation.&nbsp; The data will be in a skbuff with enough headroom
    that<BR>&gt; the channel code can easily add them if it needs
    them.<BR>&gt;<BR>&gt; Of course, 2 bytes is nothing, really, and if it makes
    life easier for<BR>&gt; most types of channel I don't mind putting them
    in.&nbsp; I thought they<BR>&gt; were really only used for async serial channels
    though (and then<BR>&gt; usually compressed out anyway).&nbsp; On balance I
    thought it was cleaner<BR>&gt; and neater not to have to worry about those 2
    bytes in the generic ppp<BR>&gt; code.<BR>&gt;<BR>&gt;
    Paul.<BR><BR>Paul:<BR><BR>The generic ppp code controls the LCP, but the LCP is
    used to negotiate<BR>media specific options, such as AFCF compression, or
    numbered transfer<BR>mode (RFC1663).<BR><BR>If the generic ppp code deals with
    data starting at the ppp protocol ID<BR>field,<BR>how do you envision
    communicating the results of the LCP negotiation<BR>to the channel which would
    implement the option.<BR><BR>Or for that matter, how does the channel
    communicate<BR>which options it supports. For example, PPP over X.25 (RFC1598)
    does<BR>not permit the AFCF compression option.<BR><BR>If we wish to define a
    generic sync adapter interface which just exchanges<BR>raw frames, does this
    imply a channel layer between such an interface<BR>and the generic ppp? For
    example: one channel for synchronous unnumbered,<BR>one for sync numbered, and
    another for X.25. All of these channels have<BR>the generic sync board interface
    on the bottom and a generic ppp interface<BR>on top?<BR><BR>Just
    curious,<BR>Paul<BR><BR>Paul Fulghum <A
    Corporation <A href=""></A><BR>9501
    Capital of Texas Hwy<BR>Austin, Texas
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