Subject: Re: [mpls] MPLS-RT review of draft-kompella-mpls-special-purpose-labels-02.txt

From: Vishwas Manral <[email-masked]>
Date: Mon, 1 Apr 2013 16:20:39 -0700

Hi Authors,

Here is my review based on guidance from Loa. I have not been following
MPLS work very closely lately, so feel free to point me to any relevant
references I may have missed:

Having worked on a draft in the past trying to allocate one of the reserved
labels, I do think the problem is present and reserved labels should have a
bigger range and that should help allocation policies to be more liberal
than in the past. The document is certainly useful.

The draft is well written, clear in its intent and is fairly cohesive. The
document does a fairly good job technically trying to cover all technical
issues that may arise. I think the document is ready to be considered for
adoption by the Working Group.

I had a few comments regarding some clarifications on the text of the
document:

1. The whole difference/ name change between "Reserved" and "Special
Purpose" labels which seems at the heart of the document is not clarified
anywhere. Though I know answers 1.A and 1.B.probably talk about it - it
should be explicitly specified.

2. Though I understand the idea of having consecutive Extension labels,
that can create issues with ASIC hardware, just as TLV's create by moving
the location of the following headers. We have talked of this in security
considerations, I see that allowing an arbitrary depth stack may force
implementations to send packets to the software path for processing, after
some depth of labels, which can cause software path overloads.

3. With "Extended Special Purpose MPLS Label Values", I think we have
created an Experimental range. The purpose of which is not clear nor is the
idea of how it is used. I also have questions on any implementation
currently using labels in the Experimental range, and how this change would
affect those implementations.

Thanks,

Vishwas

-----Original Message-----
From: Loa Andersson [mailto:[email-masked]]
Sent: Friday, March 15, 2013 4:01 PM
To: Markus Jork; Manral, Vishwas; Jia He; Thomas Morin;
[email-masked];
[email-masked]; Martin Vigoureux
Subject: MPLS-RT review of draft-kompella-mpls-special-purpose-labels-02.txt

Markus, Vishwas, Jia and Thomas,

You have been selected as an MPLS Review team reviewers for

draft-kompella-mpls-special-purpose-labels-02.

Note to authors: You have been CC'd on this email so that you can know

that this review is going on. However, please do not review your own

document.

Reviews should comment on whether the document is coherent, is it

useful (ie, is it likely to be actually useful in operational

networks), and is the document technically sound?  We are interested

in knowing whether the document is ready to be considered for WG

adoption (ie, it doesn't have to be perfect at this point, but should be

a good start).

Reviews should be sent to the document authors, WG co-chairs and

WG secretary, and CC'd to the MPLS WG email list. If necessary, comments

may be sent privately to only the WG chairs.

Are you able to review this draft by April 3, 2013?

Thanks, Loa

(as MPLS WG chair)

/Loa

-- 

Loa Andersson                        email: [email-masked]

Senior MPLS Expert                          [email-masked]

Huawei Technologies (consultant)     phone: +46 739 81 21 64 <#>

---

From: "Hejia (Jia)" <[email-masked]>
Date: Wed, 3 Apr 2013 13:18:11 +0000

Dear authors,

I have finished reviewing draft-kompella-mpls-special-purpose-labels-02.txt as the member of MPLS Review team and have the following comments:

* Is the document coherent?

Yes. The document describes a problem statement followed by solution proposals, which is easy to understand. 

* Is it useful (i.e., is it likely to be actually useful in operational networks), and is the document technically sound?
 
I believe this document is useful in general. It is good to revisit the usage policy of "reserved labels" and provide a place for discussion. There is no doubt about the scarcity of reserved labels. But the solutions (including those proposed on the mailing list) may need more time for discussion.

* Is the document ready to be considered for WG adoption?

I think the document is ready to be considered for WG adoption. But more discussion and input from the group is appreciated, especially for solutions.

Thanks!

B.R.
Jia