Subject: [PWE3] RtgDir review:draft-ietf-pwe3-fat-pw-07

From: Loa Andersson <[email-masked]>
Date: Tue, 02 Aug 2011 14:32:32 -0700

Hello,

I have been selected as the Routing Directorate reviewer for
draft-ietf-pwe3-fat-pw-07.

The Routing Directorate seeks to review all routing or
routing-related drafts as they pass through IETF last call and IESG
review, and sometimes on special request. The purpose of the review
is to provide assistance to the Routing ADs. For more information
about the Routing Directorate, please see
http://www.ietf.org/iesg/directorate/routing.html

Although these comments are primarily for the use of the Routing ADs,
it would be helpful if you could consider them along with any other
IETF Last Call comments that you receive, and strive to resolve them
through discussion or by updating the draft.

Document: draft-ietf-pwe3-fat-pw-07
Reviewer: Loa Andersson
Review Date: 2 Aug 2011
IETF LC End Date: 3 Aug 2011
Intended Status: Standards Track

Summary:
I have no major concerns about this document, howver I thing it
would be good to reslove the mostly editorial comments below
(especially on the IANA section) before publication.

Comments:

Unexpanded acronyms:

OAM appears in the table of content and as header 7. It is not
expanded in the document anywhere. Should be done at first occurance.

page 6. The last paragraph of section 1 talks about TC bits
(and EXP bits). We don't have TC bits - the correct name is TC field.

First paragraph section three:
This paragraph talks in genral about "load balanced paths" while the
rest of the document is very specific about ECMP, it is the intention
that this should work for any load balancing paradigm?

Second paragraph section three:
Normally a label is assigned by the down stream node, this scheme
is doing upstream allocation. Don't see a problem under normal
operation, but if the label "by accident" becomes top of stack
this could have "interesting" effects.

Sectyion 4 second paagraph:

OLD

    The absence of a FL Sub-TLV indicates that the PE is unable to
    process flow labels.  A PE that is using PW signalling and that does
    not send a FL Sub-TLV MUST NOT include a flow label in the PW packet.
    A PE that is using PW signalling and which does not receive a FL Sub-
    TLV from its peer MUST NOT include a flow label in the PW packet.
    This preserves backwards compatibility with existing PW
    specifications.

NEW

    The absence of a FL Sub-TLV indicates that the PE is unable to
    process flow labels.  An ingress PE that is using PW signalling
    and that does not send a FL Sub-TLV MUST NOT include a flow label
    in the PW packet. An ingress PE that is using PW signalling and
    which does not receive a FL Sub-TLV from its egress peer MUST NOT
    include a flow label in the PW packet.
    This preserves backwards compatibility with existing PW
    specifications.

The IANA section:

In the IANA section we should use a TBD entry for the Flow label
indicator; and maybe add 0x17 as suggest value in the text.

The text in the IANA section needs to aligned with the rest of
the text, or maybe even better have the rest of the text align
with the IANA section; e.g. Flow Labe intdicator is not used anywhere
else but in the iana section.

To make it easier to find the references to the IANA registries
should start with "Pseudowire Name Spaces (PWE3)" point to
"Pseudowire Interface Parameters Sub-TLV type Registry" as a
sub-registry, and ask for assigment of the next free value from
the Experts review space (suggested value 0x17).

On the other hand it looks like we have an early assigment
(Flow Label shows up with the value 0x17). If this is the case
after making the text changes suggest above this should be mentioned
in the IANA section.
-- 

Loa Andersson                         email: [email-masked]
Sr Strategy and Standards Manager            [email-masked]
Ericsson Inc                          phone: +46 10 717 52 13
                                              +46 767 72 92 13

---

From: Loa Andersson <[email-masked]>
Date: Thu, 04 Aug 2011 10:46:10 -0700

All,

I have one more point on this - I should have captured it in
the previous mail but had to think and discuss a bit about it!

Doing ECMP hashing over the label stack as described is OK, but
has one thing that needs to be taken care of. Introducing a
reserved label - most prominently the GAL - into the label
stack will change the outcome of the hash. Since we are ECMP-ing
on the hash result, we will no longer to be able to guarantee
that normal traffic and OAM packets will no longer be fate
sharing - draft-ietf-pwe3-fat-pw should say explicitly that
reserved labels should be excluded from ECMP hashing.

/Loa

--

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From: "Shahram Davari" <[email-masked]>
Date: Thu, 4 Aug 2011 10:46:53 -0700

I agree with Loa.

Thx
Shahram

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Loa Andersson
Sent: Thursday, August 04, 2011 10:46 AM
To: [email-masked]
Cc: [email-masked]; [email-masked]; [email-masked]
Subject: Re: [PWE3] RtgDir review:draft-ietf-pwe3-fat-pw-07

All,

/Loa

-- 

Loa Andersson                         email: [email-masked]
Sr Strategy and Standards Manager            [email-masked]
Ericsson Inc                          phone: +46 10 717 52 13
                                              +46 767 72 92 13
_______________________________________________
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---

From: John E Drake <[email-masked]>
Date: Thu, 4 Aug 2011 10:58:47 -0700

Loa,

This statement will also be added to the next version of the entropy label I-D.

Thanks,

John

Sent from my iPhone

> From: [email-masked] [mailto:[email-masked]] On
> Behalf Of Loa Andersson
> Subject: Re: [RTG-DIR] [PWE3] RtgDir review:draft-ietf-pwe3-fat-pw-07
> 
> All,
> 
>

---

From: "Adrian Farrel" <[email-masked]>
Date: Tue, 23 Aug 2011 13:43:42 +0100

The authors are snoozing in the sun somewhere.

> expanded in the document anywhere. Should be done at first occurance.

RFC Ed note entered

> (and EXP bits). We don't have TC bits - the correct name is TC field.

RFC Ed note entered

> that this should work for any load balancing paradigm?

Authors?

> this could have "interesting" effects.

Think this is mentioned in 1.2

> END

I think this is right. No doubt the authors were thinking of bidirectional PWs,
but with current state of the art, I think Loa is right and have entered the RFC
Ed note

> indicator; and maybe add 0x17 as suggest value in the text.

I think this is wrong because early allocation was done (as you note below).
IANA has indicated they understand the action.

> else but in the iana section.

OLD
   o  FL (value 0x17) is the flow label sub-TLV identifier assigned by
      IANA (seeSection 11 ).
NEW
   o  FL (value 0x17) is the flow label indicator sub-TLV identifier 
      assigned by IANA (see Section 11).
END

> On the other hand it looks like we have an early assignment

RFC Ed note entered

Thanks,
Adrian

---

From: "Adrian Farrel" <[email-masked]>
Date: Tue, 23 Aug 2011 13:46:26 +0100

Ah, I see why there might have been no response before.
Sending again with the correct email alias.

A

> From: Adrian Farrel [mailto:[email-masked]]
> Sent: 23 August 2011 13:44
> To: 'Loa Andersson'; [email-masked]'
> Cc: [email-masked]'; [email-masked]';
[email-masked]'
> Subject: RE: [RTG-DIR] RtgDir review:draft-ietf-pwe3-fat-pw-07
> 
> I think this is right. No doubt the authors were thinking of bidirectional
PWs, but
> with current state of the art, I think Loa is right and have entered the RFC
Ed note

---

From: "Adrian Farrel" <[email-masked]>
Date: Tue, 23 Aug 2011 13:47:00 +0100

Authors,

This needs an answer please.

It seems to me that you really don't want your hash algorithm examining labels,
but also Loa is right that GAL could mess things up.

Your thoughts?

Thanks,
Adrian

> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> Loa Andersson
> Sent: 04 August 2011 18:46

---

From: Stewart Bryant <[email-masked]>
Date: Wed, 24 Aug 2011 10:51:03 +0100

>> that this should work for any load balancing paradigm?
Although we invented the FL for ECMP, there are other types
of load balance (for example channel bonding and link bundling)
that might which to take advantage of the flow identification.
This was discussed by the WG LC.

> but with current state of the art, I think Loa is right and have entered the RFC

The change is I think the addition of the term "An ingress". Surely it 
is redundant
(but harmless) as only an ingress PE can impose a FL ... or are you 
concerned
to discriminate between TPE and SPE?

-- 
For corporate legal information go to:

http://www.cisco.com/web/about/doing_business/legal/cri/index.html

---

From: "Adrian Farrel" <[email-masked]>
Date: Wed, 24 Aug 2011 14:20:41 +0100

[Fixing the tools alias]

> From: Stewart Bryant [mailto:[email-masked]]
> Sent: 24 August 2011 10:51
> To: [email-masked]
> Cc: 'Loa Andersson'; [email-masked]; [email-masked]; [email-masked];
> [email-masked]
> Subject: Re: [PWE3] [RTG-DIR] RtgDir review:draft-ietf-pwe3-fat-pw-07
> 
PWs,
> is redundant (but harmless) as only an ingress PE can impose a FL ...
>  or are you concerned to discriminate between TPE and SPE?
>
> >> The IANA section:
> >>