RE: TCP limitations (was Re: ISCSI: Urgent Flag requirement violates TCP.)

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

Matt,

This draft
http://www.ietf.org/internet-drafts/draft-dicecco-vitcp-01.txt
uses two methods to discover data, one is an alignment of VI and TCP
segments as the recommended  implementation, and the other is a repeat of
the urgent pointer method.  Either way, a proposal that alters TCP.  Not a
simple shim, otherwise it also does not allow out of sequence processing for
direct and immediate placement of data, the goal.

Doug

> csapuntz@cisco.com wrote:
>
> > Given that shim protocol requires no changes to the TCP in the sender,
> > it is currently my favorite way of doing RDMA.
> >
> > -Costa
>
> Please see Jeff's message on 10/26.  If you don't have framing,
> when you lose
> a segment, you need to buffer generic TCP segments on the NIC
> before you can
> "RDMA" them somewhere, because you don't know where the "RDMA"
> information is
> in the "byte stream".
>
> -Matt
>