RE: iSCSI Framing Formats

["Nate Lawson" <nate@decru.com>]

FYI, I don't know which approach has been decided either.

> -----Original Message-----
> From: owner-ips@ece.cmu.edu On Behalf Of Trang Nguyen
> I've read your discussion about how to find iSCSI PDU header from the TCP
> stream at the receiving end.  There are 2 different approaches
> with various ways:
>
> 1.  TCP unaware approach suggests: periodic marker, fixed length messages,
> byte stuffing, chunks.

I recommend these, and in particular, TLV headers (Type, Length, Value).
TLV headers are used for IP options, for instance.  Fixed length usually
implies overhead for short messages, periodic marker implies the need to
escape inband data, etc.  Finally, these other approaches aren't expandable
for future standards.

> 2.  TCP aware approach suggests: Urgent pointer, and PSH bit.
> I found that there are some objections about using Urgent point
> and PSH bit because the TCP has to be modified.

Terrible.  There is no agreement on the meaning of the UP and all stacks
that I know of ignore PSH as well as there being no user-level way of
setting it on any OS I've used.

I'm curious too.  What approach(es) are supported?

-Nate