Subject: [rbridge] I-D Action: draft-ietf-trill-rbridge-extension-01.txt

From: [email-masked]
Date: Thu, 22 Dec 2011 09:08:04 -0800

A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Transparent Interconnection of Lots of Links Working Group of the IETF.

	Title           : TRILL: Header Extension
	Author(s)       : Donald Eastlake
                          Anoop Ghanwani
                          Vishwas Manral
                          Caitlin Bestler
	Filename        : draft-ietf-trill-rbridge-extension-01.txt
	Pages           : 16
	Date            : 2011-12-22

   The TRILL base protocol standard specifies minimal hooks to safely
   support TRILL Header extensions. This document specifies an initial
   extension providing additional flag bits and specifies one of those
   bits.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-trill-rbridge-extension-01.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

This Internet-Draft can be retrieved at:
ftp://ftp.ietf.org/internet-drafts/draft-ietf-trill-rbridge-extension-01.txt

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From: Donald Eastlake <[email-masked]>
Date: Thu, 22 Dec 2011 12:17:38 -0500

This revision just has editorial changes and author information update.

Thanks,
Donald
=============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 155 Beaver Street, Milford, MA 01757 USA
 [email-masked]

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From: Yizhou Li <[email-masked]>
Date: Mon, 26 Dec 2011 20:26:21 +0800

Hi Donald,

Some comments and thoughts when I read the draft,

1. pg4, right below bullets
   "Any RBridge receiving a frame with a critical hop-by-hop extension
   that it does not implement MUST discard the frame because it is
   unsafe to process the frame without understanding such a critical
   extension. Any egress RBridge receiving a frame with a critical
   ingress-to-egress or hop-by-hop extension it does not implement MUST
   drop the frame if it is a known unicast frame; if it is a multi-
   destination TRILL Data frame, then it MUST NOT be egressed at that
   RBridge but it is still forwarded on the distribution tree. Non-
   critical extensions can be safely ignored."

It is unclear to me what a RB should do if it receives a multi-destination
frame with a critical hop-by-hop extension that it does not implement?
1st sentence suggests to discard it and the end of second last sentence
suggests to forward it on the tree?
Suggest to remove "or hop-by-hop" in 2nd sentence.

2. pg5, L3, "some such frames them to be" -> some of them to be

3. pg7, section 2.3.1, 
Can we call "extensions after the first word in the extensions area" to be
"TLV extensions"?
Another general comment, use a table to show the whole extension area
structure which contains the Extension Header Flags as that in section 2.3
and the optional non-flag TLV extensions which is 32-bit aligned. 

4. pg4, bottom, Note section.
I think there is mixture of slow path & fast path case if future hardware
can support certain flag directly, e.g. some flag requires forwarding the
frame in data plane as normal and copy it to the control plane for further
processing at the same time. 

5. pg10, section 3. Table 1. Extended Header Flags Area
Suggest to define bit 3 for a critical hop-by-hop RBridge Channel Alert
Flag. It may be useful in assisting some channel features, like the source
routing with strict path specified.

6. pg8, section 2.4 
Better to explicitly state that the conflicts may not be resolved to achieve
the same consequence at every transit RB for a single data frame even
following the rules described. It highly depends on the capability that an
RB can support.

Thanks,
Yizhou

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Donald Eastlake
Sent: Friday, December 23, 2011 1:18 AM
To: [email-masked]
Subject: Re: [rbridge] I-D Action: draft-ietf-trill-rbridge-extension-01.txt

Thanks,
Donald

On Thu, Dec 22, 2011 at 12:08 PM,  <[email-masked]> wrote:
>
> A New Internet-Draft is available from the on-line Internet-Drafts
directories. This draft is a work item of the Transparent Interconnection of
Lots of Links Working Group of the IETF.
> A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-trill-rbridge-extension-01.tx
t