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Re: Gen-ART review of draft-ietf-mpls-tp-ethernet-addressing-05

2013-04-02 09:27:33
Thanks for following up, and for the re-send.  Just to be clear, I do not
mean these as blocking points.

On the former point, I might just suggest a minor edit to the introduction:
OLD: "This document specifies the options for determination and selection
of next-hop Ethernet MAC addressing under these circumstances."
NEW: "This document specifies the options for determination and selection
of next-hop Ethernet MAC addressing when MPLS-TP is used in a "pure
Ethernet" manner, without any IP forwarding capability."

On the latter point, I can understand the desire to make the simple case
simple, and the text at the end of Section 2 sends a clear warning. It does
seems like GAP would also allow autoconfiguration without further NMS
interaction.  (Unless the NMS is configuring per-Ethernet-address policies,
e.g., "forward packets with this label to 00:11:22:33:44:55". Is that the
case?)




On Tue, Apr 2, 2013 at 9:10 AM, Stewart Bryant <stbryant(_at_)cisco(_dot_)com> 
wrote:

 Resending due to Richards change of address.

Stewart


On 11/02/2013 23:45, Richard Barnes wrote:

I have been selected as the General Area Review Team (Gen-ART) reviewer for 
this draft (for background on Gen-ART, 
pleaseseehttp://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html).

Please wait for direction from your document shepherd or AD before posting a 
new version of the draft.

Document: draft-ietf-mpls-tp-ethernet-
addressing-05
Reviewer: Richard Barnes
Review Date: 2013-02-11
IETF LC End Date: 2013-02-18
IESG Telechat date: TBD

Summary:  Ready, with a couple of minor questions / clarifications.

Comment:

The document is mostly very clearly written.  (Thanks!)  It would have helped 
me understand if it could have been clarified up front that the mechanism in 
this document is intended for "pure Ethernet" MPLS-TP (without assumptions 
about layer 3+).  The current introduction says as much, but in a negative 
way, in terms of ARP or ND not being available.

I have some minor unease about the distinction that this document makes 
between point-to-point and multipoint links.  The document correctly notes 
that a point-to-point link might become multipoint without either end being 
aware.  I would have thought this would argue for using GAP in all cases, but 
instead the document carries on with addressing the point-to-point case 
separately..


 Richard

It is always difficult when writing a simple draft dealing with a small
component of a larger technology to know how much tutorial to include,
but I believe the point about operation in the absence IP would be well
known
to anyone implementing this. In particular we assume that anyone
implementing the draft would have read the required references called
up in the first paragraph of the Introduction:


" The MPLS Transport Profile (MPLS-TP) [RFC5921] is the set of protocol
functions that meet the requirements [RFC5654] for the application of
MPLS to the construction and operation of packet-switched transport
networks. The MPLS-TP data plane consists of those MPLS-TP functions
concerned with the encapsulation and forwarding of MPLS-TP packets
and is described in [RFC5960]."

RFC5654 says:

"   36  It MUST be possible to operate and configure the MPLS-TP data
       plane without any IP forwarding capability in the MPLS-TP data
       plane.  That is, the data plane only operates on the MPLS label."
Thus I think that the text is complete as it stands and requires no
further clarification for anyone that needs to consider the technology
it describes.


With regard to your second point, the issue that we are have, is that
there are a number of deployment scenarios where the operator knows
that the link is Pt-Pt, and there is a reluctance by that community to
use anything other than NMS configuration. That has lead them
to use Ethernet broadcast addressing which allows the crafts to
change h/w without the need for reconfiguration by the NMS.
Against that background moving them onto the use of a Ethernet m/c
address is a step forward. To require using the GAP to that
community would illustrate that the IETF is out of touch with
their needs and methods of network operation.

Hopefully this additional background, which I believe is well
known to the MPLS-TP community to which this draft is directed,
satisfies your concern on the latter point.

- Stewart



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