Messages in this thread | | | From | "Paul Fulghum" <> | Subject | Re: Synchronous board drivers | Date | Wed, 7 Jul 1999 16:05:43 -0500 |
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content="text/html; charset=iso-8859-1" http-equiv=Content-Type> <META content="MSHTML 5.00.2014.210" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face=Arial size=2>From: Paul Mackerras <<A href="mailto:paulus@cs.anu.edu.au">paulus@cs.anu.edu.au</A>><BR><BR>> The address and control bytes are really part of the medium-specific<BR>> encapsulation. The data will be in a skbuff with enough headroom that<BR>> the channel code can easily add them if it needs them.<BR>><BR>> Of course, 2 bytes is nothing, really, and if it makes life easier for<BR>> most types of channel I don't mind putting them in. I thought they<BR>> were really only used for async serial channels though (and then<BR>> usually compressed out anyway). On balance I thought it was cleaner<BR>> and neater not to have to worry about those 2 bytes in the generic ppp<BR>> code.<BR>><BR>> 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 href="mailto:paulkf@microgate.com">paulkf@microgate.com</A><BR>Microgate Corporation <A href="http://www.microgate.com">www.microgate.com</A><BR>9501 Capital of Texas Hwy<BR>Austin, Texas 78759<BR>(512)-345-7791<BR></FONT></DIV></BODY></HTML>
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