Re: ISCSI: Detail on counting offset for fixed markers

[julian_satran@il.ibm.com]

Barry,

In 06 it will read:

   The Marker indicates the offset to the next iSCSI PDU header.  The
   Marker is eight bytes in length, and contains two 32-bit offset fields
   that indicate how many bytes to skip in the TCP stream in order to find
   the next iSCSI PDU header.  The offset is counted from the marker end to
   the beginning of the next header.  The marker uses two copies of the
   pointer so that a marker spanning a TCP packet boundary should leave at
   least one valid copy in one of the packets.


   Thanks,
   Julo

"Barry Reinhold" <bbrtrebia@mediaone.net> on 04/04/2001 17:29:59

Please respond to "Barry Reinhold" <bbrtrebia@mediaone.net>

To:   Julian Satran/Haifa/IBM@IBMIL
cc:   "ISCSI" <ips@ece.cmu.edu>
Subject:  ISCSI: Detail on counting offset for fixed markers




Julian,
     A mundane clearification that need to go into the specification
relative to
appendix C (Fixed Markers). It currently reads:

"The Marker indicates the offset to the next iSCSI message header.
   The Marker is eight bytes in length, and contains two 32-bit offset
   fields that indicate how many bytes to skip in the TCP stream in
   order to find the next iSCSI message header.  The marker uses two
   copies of the pointer so that a marker spanning a TCP packet boundary
   will leave at least one valid copy in one of the packets."

Since we are counting bytes, does the offset start after the 4 bytes that
make up this copy of the pointer (exculdes pointer)or does it start with
the
first byte of the pointer (includes pointer)?

A third option is that it starts after both copies of the pointers so that
the two values are the same....




Barry Reinhold
Principal Architect
Trebia Networks
barry.reinhold@trebia.com
603-868-5144/603-659-0885/978-929-0830 x138