RE: FCIP: draft-weber-fcip-encaps-00.txt

["Douglas Otis" <dotis@sanlight.net>]

Ralph,

As an alternative to byte stuffing, creating a pseudo-frame within TCP would
be an alternative.  Here is an example of using SCTP within TCP using a
fixed interval alignment of a pseudo-frame allowing frame recovery where
padding is inserted should the pseudo-frame be smaller than the predefined
interval.  This interval could be negotiated at 4096 or 8192 as example.  If
used within SCTP, the real Ethernet frame becomes the interval.  The SCTP
Data Chunk would contain the FCIP Header and FC frame.  Digest error
handling and acknowledgement would be done at the pseudo-frame using the
SCTP SACK chunk.  Encapsulating FCIP within SCTP within TCP has advantages
with the addition of all the interesting features of SCTP such as
multi-homing, session recovery, anti-spoofing, defined negotiations, and
years of effort creating a well defined transport.  By using Adler-32 over
the entire frame, much of the repeated values can be removed from your
specifications as well.

Constructing the pseudo-frame should represent little additional overhead
than that required to process byte stuffing.  You could require all FC
frames to be contained within a single pseudo-frame, but if SCTP is actually
used, constructing the FC frame should be an additional step.   Once SCTP is
used directly, the additional secondary overhead to process digest errors is
removed and FC related data becomes aligned with the Ethernet frame.
Something you should consider in any transport, is the handshake to allow
error recovery.  SCTP covers those questions as well as adds many
interesting advantages.  FCIP is but one of the many possible encapsulation
possible with SCTP.  SCTP can be placed on TCP (less flow control), UDP, and
of course as SCTP itself.  The general purpose structure of SCTP allows
interesting opportunities for encapsulation including the encapsulation of
the entire network connection between machines as example.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +---------------+---------------+---------------+---------------+
  0|    Rev        |   Reserved    |    Pseudo-Frame Word Length   |
   +---------------+---------------+---------------+---------------+
  4|                         Validation Tag                        |
   +---------------+---------------+---------------+---------------+
  8|                       Checksum (Adler32)                      |
   +---------------+---------------+---------------+---------------+

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 12|   Type = 0    | Reserved|U|B|E|       Chunk Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 16|                              TSN                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 20|      Stream Identifier S      |   Stream Sequence Number n    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 24|             Payload Protocol Identifier (IANA FCIP Op)        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 28|  VER. |HDR Len|                    Reserved                   |
   +-------+-------+---------------------------+-------------------+
 32|                         Time Integer                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 36|                         Time Fraction                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 40\                                                               \
   /                 FC encapsulation (seq n of Stream S)          /
   \                                                               \

Doug


> -----Original Message-----
> From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
> Ralph Weber
> Sent: Thursday, February 15, 2001 5:49 AM
> To: IPS Reflector
> Subject: FCIP: draft-weber-fcip-encaps-00.txt
>
>
> An internet draft titled " FCIP Frame Encapsulation Enhancement
> Proposals" is available at:
>
> http://www.ietf.org/internet-drafts/draft-weber-fcip-encaps-00.txt
>
> The abstract is as follows:
>
>    This draft is for consideration by the FCIP team in the IPS working
>    group.  Improvements to Fibre Channel Over TCP/IP (FCIP) [2] frame
>    encapsulation mechanisms are proposed.  The objectives of the
>    improvements are two fold: increasing the reliability of Fibre
>    Channel frame detection, and assisting with the handling of Fibre
>    Channel E_D_TOV and R_A_TOV time-out processing.
>
> Since the ID was submitted a technical error was discovered in
> section 3.2, Time Stamp, it says that the integer word in the
> time stamp is "the time in seconds relative to the epoch,
> 00:00:00 January 1,1990."  This is a transcription from the
> T11 proposal on which the usage of this time format is based
> (01-052v0).
>
> However, 01-052v0 is based on SNTP (RFC 2030) and RFC 2030 says
> that the base epoch is "00:00:00 January 1,1900", that is 1900
> not 1990.
>
> I have been informed that 01-052v0 did not intend to revise
> RFC 2030 and that the encapsulation proposal should use 1900
> not 1990.
>
> FYI
>
> Ralph Weber
> representing
> Brocade Communications
>
>
>