Subject: [imss] Re: IMSS WG last call on Transmission of IPv6, IPv4 and ARP Packets over Fibre Channel

From: Claudio DeSanti <[email-masked]>
Date: Wed, 23 Feb 2005 09:54:10 -0800

Elizabeth,

just a couple of notes to help people reviewing this document.

As agreed at the last WG meeting, this document incorporates and clarifies 
RFC 3831. The differential document 
http://www.t11.org/ftp/t11/pub/fc/ipv4fc/05-093v0.pdf lists the differences 
with RFC 3831.

draft-ietf-imss-ip-over-fibre-channel-00.txt introduces also a small 
technical change to RFC 3831, a change regarding the position of the 
padding in the Neighbor Discovery Link-layer Address option. RFC 3831 (in 
figure 20) prepended two bytes of padding to the Link-layer Address, in 
order to have a better aligned option. Early implementors of RFC 3831 found 
difficult to implement this prepended padding, because it has been 
discovered that current implementations of Neighbor Discovery assume that 
the padding is always appended to the Link-layer Address.

Given that Fibre Channel developers often develops only a driver for the 
Fibre Channel interface and do not have access to the operating system code 
that handles Neighbor Discovery, the only way to implement RFC 3831 would 
have been then to trap each received Link-layer Address option, reformat it 
by putting the padding after the Link-layer Address, and then pass the 
reformatted option to the O.S. The opposite process would have to be 
performed when the O.S. generates a Link-layer address option. This 
completely overcomes the intent of the better alignment of the option, 
which was to make implementations more efficient. For this reason, 
draft-ietf-imss-ip-over-fibre-channel-00.txt put instead the padding after 
the Link-layer Address (see figure 23).

Gien that there are not yet implementations of RFC 3831 in the field, this 
change does not introduce any backward compatibility problem and fixes the 
only implementation issue found in RFC 3831.

Fibre Channel is not the only technology that has to deal with padding in 
the Neighbor Discovery Link-layer Address option. As an example, also the 
IP over Infiniband WG is dealing with a similar issue about prepending or 
appending the padding.

Best regards,

                             Claudio.

At 04:58 PM 2/22/2005 -0800, [email-masked] wrote:

>Hello all,
>
>I would like to announce IMSS working group last call on the Transmission of
>IPv6, IPv4 and ARP Packets over Fibre Channel working group draft.
>
>Details:
>Name: Transmission of IPv6, IPv4 and ARP Packets over Fibre Channel
>URL:
>http://www.ietf.org/internet-drafts/draft-ietf-imss-ip-over-fibre-channel-00
>.txt
>Editor/Authors: Claudio DeSanti ([email-masked]), Craig Carlson
>([email-masked]) and Bob Nixon ([email-masked])
>Last Call period: Three weeks, ending March 17 at 11:59pm EST.
>
>Technical comments on the MIB should be discussed on the IMSS reflector at
>[email-masked].  Editorial comments may be discussed on the reflector or be
>submitted to the editor/authors directly at the above addresses, with a copy
>to Elizabeth Rodriguez at [email-masked].
>
>Thanks,
>
>Elizabeth Rodriguez
>IMSS Chair
>
>To Unsubscribe:
>mailto:[email-masked]?subject=unsubscribe

_______________________________________________
imss mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/imss