Subject: Re: FWD: Last Call: Transmission of IPv6 Packets over IEEE 1394 Networks to Proposed Standard

From: Eric Anderson <[email-masked]>
Date: Thu, 22 Feb 2001 13:14:58 -0800

I wish to endorse what Peter has suggested.  The present IP1394
design does not make effective use of 1394's highest-performance
transfer modes: Physical DMA, Asynchronous Streams, and Isochronous
transfer, and consequently the performance is low and the overhead
very high.  At least for use on a local 1394 bus, among peers such
as multiple computers, we should adopt a more efficient transfer
mechanism to carry IP on 1394, perhaps falling back to the existing
scheme when talking to devices that are not designed for high
performance operation.  I would be happy to work with other
interested parties to define such a mechanism.

--------------------------------------
Eric Anderson            [email-masked]
Apple Computer, Inc.      408-974-1394
--------------------------------------

On Thu, Feb 22, 2001 11:50 AM, Peter Johansson wrote:
>At 06:47 AM 2/20/01, Thomas Narten wrote:
>
>>The IESG has received a request from the IPNG Working Group to
>>consider Transmission of IPv6 Packets over IEEE 1394 Networks
>><draft-ietf-ipngwg-1394-01.txt> as a Proposed Standard.
>
>I suggest that the forward progress of the Draft-IETF-IPNGWG-1394-01
>to Proposed Standard be delayed to permit the formation of a new
>IP1394 Working Group. In broad terms, the charter of the IP1394
>working group would be twofold: a) the revision of IP over 1394
>protocols to permit significantly increased end-to-end efficiency
>and b) the extension of IP over 1394 protocols to include IPv6. With
>respect to the second element of scope, I think the working group
>would not start afresh but would utilize all of the appropriate
>components of the valuable effort already contained within Draft-
>IETF-IPNGWG-1394-01. It is the first element of scope that is the
>driving reason for forming a new working group.
>
>I do not presume to speak for others (I hope that major operating
>systems vendors will speak for themselves), but I know from
>conversations that both Apple and Microsoft are seriously concerned
>with the relatively poor performance characteristics of IPv4 over
>IEEE 1394. The performance is relatively poor when one examines the
>practical throughput of a 100, 200 or 400 Mbps IEEE 1394 bus and
>compares it with the effective end-to-end throughput achieved by
>IP1394. When I say "practical" throughput, I do not mean a
>theoretical maximum but an empirical value observable when other
>protocols well-suited to mass data transfer (e.g., SBP-2) are
>scrutinized.  For example, the BEST end-to-end throughput on a 400
>Mbps bus observed to date is a wretched 100 Mbps. Instead of the
>25% efficiency achieved, a more efficient IP1394 protocol should
>be able to effect 85%!
>
>The source of the problem is that each IP datagram (or fragment)
>generates an interrupt at the receiving system. The resultant
>inefficiency at the receiving host hobbles the effective
>throughput. This behavior is intrinsic in RFC 2734. I suggest that
>a new working group be chartered to examine this problem and
>redesign portions of the IP1394 protocol to improve its efficiency.
>
>Because Draft-IETF-IPNGWG-1394-01 is based upon RFC 2734 and
>inherits its problems, I suggest it would be prudent to delay
>advancement of the Internet Draft to a proposed. The efforts of a
>new IP1394 working group are likely to render some of the
>provisions of the current work moot.
>
>
>Regards,
>
>Peter Johansson
>
>Congruent Software, Inc.
>98 Colorado Avenue
>Berkeley, CA  94707
>
>(510) 527-3926
>(510) 527-3856 FAX
>
>[email-masked]