Article ID: 103026
Article Last Modified on 11/1/2006
APPLIES TO
- Microsoft Windows NT Advanced Server 3.1
- Microsoft Windows NT Workstation 3.1
- Microsoft Windows NT Advanced Server 3.1
This article was previously published under Q103026
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 KB103026