Required addition to FC-FS to protect legacy usage of reserved codes for FCP-2

Robert Snively rsnively at
Fri Nov 9 16:04:48 PST 2001

* From the T10 Reflector (t10 at, posted by:
* Robert Snively <rsnively at>
It has come to my attention that some early implementations of
FCP-2 implemented the REC FCP-2 Link Service Requests as
Extended Link Services instead of FC-4 Link Services.
This was based on early drafts of the FCP-2 and FC-TAPE

While these implementations are non-standard, the problem 
would only become serious if the Extended Link Service 
command codes previously assigned to REC were reassigned 
for some other purpose.

I propose that the following changes be made in FC-FS to
prevent any such dangerous behavior and to allow the legacy
implementations to smoothly migrate to the standard.

In table 59, "ELS Command Codes", two new rows should be
defined, each having no abbreviation and no reference:

   hex '13'     vendor specific (see note a)

   hex '14'     vendor specific (see note a)

A footnote "a" should be provided to the table as follows:

Note a)	Some early implementations of FCP-2 may have
		used the value hex '13' for REC (Read Exchange
		Concise) and hex '14' for SRR (Sequence 
		Retransmission Request).  These codes are
		made vendor specific in this standard to avoid conflicts
		with such legacy FCP-2 usage.  See FCP-2
		for the standard implementation of REC and
		SRR as FC-4 Link Services.

Bob Snively                        e-mail:    rsnively at
Brocade Communications Systems     phone:  408 487 8135
1745 Technology Drive
San Jose, CA 95110

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