DOCUMENT:Q103026  08-AUG-2001  [winnt]
TITLE   :RAS Frame Format Diagram
PRODUCT :Microsoft Windows NT
PROD/VER:3.1
OPER/SYS:
KEYWORDS:kbnetwork

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Windows NT Server version 3.1 
 - Microsoft Windows NT Workstation version 3.1 
 - Microsoft Windows NT Advanced Server, version 3.1 
-------------------------------------------------------------------------------

Below is a diagram indicating the format of Remote Access Service
(RAS) frames:

                  +---+---+---+---+------  --------+---+---+---+

   RAS 1.0 frame  |SYN|SOH| LENGTH| <--> Data <--> |03h|  CRC  |
   asybeui frame  +---+---+---+---+------  --------+---+---+---+

                       ^
                       |--SOH_BCAST or SOH_DEST

                  +---+---+---+---+---+------  --------+---+---+---+

   RAS 2.0 frame  |SYN|SOH| LENGTH|COH| <--> Data <--> |ETX|  CRC  |
   asybeui frame  +---+---+---+---+---+------  --------+---+---+---+
   with compress       ^

                       |--(SOH_BCAST|SOH_COMPRESS)
                          or (SOH_DEST|SOH_COMPRESS)

                  +---+---+---+---+---+------  --------+---+---+---+

   RAS 2.0 frame  |SYN|SOH| LENGTH|COH| <--> Data <--> |ETX|  CRC  |
   asybeui frame  +---+---+---+---+---+------  --------+---+---+---+
   with compress   ^   ^
   with XON/XOFF   |   |--(SOH_BCAST|SOH_COMPRESS)

                   |      or (SOH_DEST|SOH_COMPRESS)
                   |
                   +-------(SYN | SYN_XONXOFF)

                  +---+---+---+---+---+---+-----  -------+---+--+--+

   RAS 2.0 frame  |SYN|SOH| LENGTH| E-TYPE|<--> Data <-->|ETX| CRC |
   with TCP/IP    +---+---+---+---+---+---+-----  -------+---+--+--+
   no compress         ^

                       |--(SOH_BCAST|SOH_TYPE) or (SOH_DEST|SOH_TYPE)

                  +---+---+---+---+---+---+---+----  ------+---+--+--+

   RAS 2.0 frame  |SYN|SOH| LENGTH| E-TYPE|COH|<-> Data <->|ETX| CRC |
   with TCP/IP    +---+---+---+---+---+---+---+----  ------+---+--+--+
   and compress        ^

                       |--(SOH_BCAST|SOH_TYPE|SOH_COMPRESS)
                          or (SOH_DEST|SOH_TYPE|SOH_COMPRESS)

   NOTE: Compression is performed after COH and before ETX. This does
   mean that E-TYPE is not compressed. Also, when CRC is performed,
   SOH through ETX (inclusive) is checked. ETX is included because RAS
   1.0 also checked ETX.

   SYN          = 0x16
   SOH_BCAST    = 0x01
   SOH_DEST     = 0x02
   SOH_TYPE     = 0x80
   SOH_COMPRESS = 0x40
   SYN_XONXOF   = 0x20
   CRC          = 16 bit CRC polynomial (Big-Endian format)
   LENGTH       = length of Data part of frame (two-byte Big-Endian)

======================================================================
Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW310 kbWinNTSsearch kbWinNTS310 kbWinNTAdvSerSearch kbWinNTAdvServ310 kbWinNTS310search kbWinNT310Search kbWinNTW310Search
Version           : 3.1

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.