Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Cyril Margaria]

Hi,

I think the text from Stephane solve well the no-path case, if a PCE would
like to force a tear-down of the LSP, the admin-status bit seems
appropriate.
In the case you mention, a PCE may sets a loose hop towards egress, but its
up to the PCC to expand or not the ERO.

BR
Cyril


On 11 October 2016 at 19:16, Sudhir Cheruathur <scheruat...@juniper.net>
wrote:

> Stephane/Dhruv/Xian,
>
>
>
> I am concerned with the need to revoke the delegation when there is no
> path. Today, we can change three attributes of a delegated LSP - Path
> (ERO), Bandwidth and Metric.
>
>
>
> Are we suggesting that when BW and/or Metric is changed it must always be
> accompanied with a path? How would you handle cases where only BW and/or
> Metric is changed for a delegated LSPs from controller that has no
> computation engine or would prefer the PCC to do the computation?  Yes,
> keep the existing path could be an option but since it is not always
> guaranteed we will need appropriate error handling.
>
>
>
> Thanks
>
> Regds
> Sudhir C
>
>
>
>
>
> *From: *Pce <pce-boun...@ietf.org> on behalf of "
> stephane.litkow...@orange.com" <stephane.litkow...@orange.com>
> *Date: *Tuesday, October 11, 2016 at 4:14 AM
> *To: *Dhruv Dhody <dhruv.i...@gmail.com>, "Zhangxian (Xian)" <
> zhang.x...@huawei.com>
> *Cc: *"pce@ietf.org" <pce@ietf.org>
> *Subject: *Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE
> advising PCC about no path
>
>
>
> Hi,
>
>
>
> I would rather prefer to have a more generic statement for the PCC local
> policy :
>
>
>
> The ERO may be empty if the PCE cannot find a valid path for a delegated
> LSP. One typical situation resulting in this empty ERO carried in the PCUpd
> message is that a PCE can no longer find a strict SRLG-disjoint path for a
> delegated LSP after a link failure.  The PCC SHOULD implement a local
> policy to decide the appropriate action to be taken: tear down LSP, revoke
> delegation and use a locally computed path, keep existing LSP state …
>
>
>
> Brgds,
>
>
>
>
>
> *From:* dhruvdh...@gmail.com [mailto:dhruvdh...@gmail.com] *On Behalf Of 
> *Dhruv
> Dhody
> *Sent:* Monday, October 10, 2016 06:45
> *To:* Zhangxian (Xian)
> *Cc:* LITKOWSKI Stephane OBS/OINIS; DUGEON Olivier IMT/OLN; Aissaoui,
> Mustapha (Nokia - CA); MEURIC Julien IMT/OLN; pce@ietf.org
> *Subject:* Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE
> advising PCC about no path
>
>
>
> Hi Xian,
>
>
>
> I would avoid saying set of *paths* for delegated LSP, instead I would
> modify your text slightly as -
>
>
>
> The ERO may be empty if the PCE cannot find a valid path for a delegated
> LSP. One typical situation resulting in this empty ERO carried in the PCUpd
> message is that a PCE can no longer find a strict SRLG-disjoint path for a
> delegated LSP after a link failure.  If the PCC's local policy allows it,
> it SHOULD signal the tear down of the LSP. Alternatively, PCC MAY revoke
> delegation and use a locally computed path instead.
>
>
>
> Regards,
>
> Dhruv
>
>
>
> On Mon, Oct 10, 2016 at 8:15 AM, Zhangxian (Xian) <zhang.x...@huawei.com>
> wrote:
>
> Hi, Stephane,  Olivier, All,
>
>
>
>   I support the option 1 Dhruv proposed (see below), which has least
> impact on existing implementations.
>
>
>
> >(1) Allow Empty ERO to mean no path.
>
> >Let it be valid in all messages to mean that no intended path exists for
> this LSP.
>
> >As per -16,
>
> >- empty ERO is added in the end of synchronization marker (PCRpt).
>
> >- The ERO may be empty if the PCE does not have a path for a delegated
> LSP.
>
>
>
> >We can add text in section 6.2 to say something like –
>
>
>
> >The ERO may be empty if the PCE does not have an intended path for the
> delegated LSP.
>
> >If the local policy allows it, the PCC SHOULD signal the tear down of
> the LSP. At
>
> >this time, PCC MAY also revoke delegation and use a locally computed
> path instead.
>
>
>
> >To me this is more logical and in spirit with the rest of the document,
> also would require least amount of changes in existing implementations.
>
>
>
> If we have rough consensus, we should start to work on the changes  needed
> in draft-ietf-pce-stateful-pce-16 to clarify, I would propose to add the
> following sentences in somewhere in Section 6.2 (edited on top of what
> Dhruv has suggested above):
>
>
>
> The ERO may be empty if the PCE cannot find one or a set of valid paths
> for a delegated LSP.  One t

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Sudhir Cheruathur]

Stephane/Dhruv/Xian,

I am concerned with the need to revoke the delegation when there is no path. 
Today, we can change three attributes of a delegated LSP - Path (ERO), 
Bandwidth and Metric.

Are we suggesting that when BW and/or Metric is changed it must always be 
accompanied with a path? How would you handle cases where only BW and/or Metric 
is changed for a delegated LSPs from controller that has no computation engine 
or would prefer the PCC to do the computation?  Yes, keep the existing path 
could be an option but since it is not always guaranteed we will need 
appropriate error handling.

Thanks
Regds
Sudhir C


From: Pce <pce-boun...@ietf.org> on behalf of "stephane.litkow...@orange.com" 
<stephane.litkow...@orange.com>
Date: Tuesday, October 11, 2016 at 4:14 AM
To: Dhruv Dhody <dhruv.i...@gmail.com>, "Zhangxian (Xian)" 
<zhang.x...@huawei.com>
Cc: "pce@ietf.org" <pce@ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi,

I would rather prefer to have a more generic statement for the PCC local policy 
:

The ERO may be empty if the PCE cannot find a valid path for a delegated LSP. 
One typical situation resulting in this empty ERO carried in the PCUpd message 
is that a PCE can no longer find a strict SRLG-disjoint path for a delegated 
LSP after a link failure.  The PCC SHOULD implement a local policy to decide 
the appropriate action to be taken: tear down LSP, revoke delegation and use a 
locally computed path, keep existing LSP state …

Brgds,


From: dhruvdh...@gmail.com [mailto:dhruvdh...@gmail.com] On Behalf Of Dhruv 
Dhody
Sent: Monday, October 10, 2016 06:45
To: Zhangxian (Xian)
Cc: LITKOWSKI Stephane OBS/OINIS; DUGEON Olivier IMT/OLN; Aissaoui, Mustapha 
(Nokia - CA); MEURIC Julien IMT/OLN; pce@ietf.org
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Xian,

I would avoid saying set of *paths* for delegated LSP, instead I would modify 
your text slightly as -

The ERO may be empty if the PCE cannot find a valid path for a delegated LSP. 
One typical situation resulting in this empty ERO carried in the PCUpd message 
is that a PCE can no longer find a strict SRLG-disjoint path for a delegated 
LSP after a link failure.  If the PCC's local policy allows it, it SHOULD 
signal the tear down of the LSP. Alternatively, PCC MAY revoke delegation and 
use a locally computed path instead.

Regards,
Dhruv

On Mon, Oct 10, 2016 at 8:15 AM, Zhangxian (Xian) 
<zhang.x...@huawei.com<mailto:zhang.x...@huawei.com>> wrote:
Hi, Stephane,  Olivier, All,

  I support the option 1 Dhruv proposed (see below), which has least impact 
on existing implementations.

>(1) Allow Empty ERO to mean no path.
>Let it be valid in all messages to mean that no intended path exists for this 
>LSP.
>As per -16,
>- empty ERO is added in the end of synchronization marker (PCRpt).
>- The ERO may be empty if the PCE does not have a path for a delegated LSP.

>We can add text in section 6.2 to say something like –

>The ERO may be empty if the PCE does not have an intended path for the 
>delegated LSP.
>If the local policy allows it, the PCC SHOULD signal the tear down of the LSP. 
>At
>this time, PCC MAY also revoke delegation and use a locally computed path 
>instead.

>To me this is more logical and in spirit with the rest of the document, also 
>would require least amount of changes in existing implementations.

If we have rough consensus, we should start to work on the changes  needed in 
draft-ietf-pce-stateful-pce-16 to clarify, I would propose to add the following 
sentences in somewhere in Section 6.2 (edited on top of what Dhruv has 
suggested above):

The ERO may be empty if the PCE cannot find one or a set of valid paths for a 
delegated LSP.  One typical situation resulting in this empty ERO carried in 
the PCUpd message is that PCE can no longer find two strictly SRLG-disjoint 
paths for a delegation LSP after link failure.  If its local policy allows it, 
the PCC SHOULD signal the tear down of the LSP. Alternatively, PCC MAY revoke 
delegation and use a locally computed path instead.

Does the text look good to address the ambiguity issue you raised?

Regards,
Xian

发件人: Pce [mailto:pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>] 代表 
stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>
发送时间: 2016年10月6日 15:19
收件人: DUGEON Olivier IMT/OLN; Aissaoui, Mustapha (Nokia - CA); MEURIC Julien 
IMT/OLN; pce@ietf.org<mailto:pce@ietf.org>
主题: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC 
about no path

Hi Olivier,

I think we almost have a consensus on using the current ERO object with the 
semantic “I have no intended path”, so adding a new sibling object is not 
necessary.
It would then be up to the PCC to have a local p

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Dhruv Dhody]

Hi Xian,

I would avoid saying set of *paths* for delegated LSP, instead I would
modify your text slightly as -

The ERO may be empty if the PCE cannot find a valid path for a delegated
LSP. One typical situation resulting in this empty ERO carried in the PCUpd
message is that a PCE can no longer find a strict SRLG-disjoint path for a
delegated LSP after a link failure.  If the PCC's local policy allows it,
it SHOULD signal the tear down of the LSP. Alternatively, PCC MAY revoke
delegation and use a locally computed path instead.


Regards,
Dhruv

On Mon, Oct 10, 2016 at 8:15 AM, Zhangxian (Xian) <zhang.x...@huawei.com>
wrote:

> Hi, Stephane,  Olivier, All,
>
>
>
>   I support the option 1 Dhruv proposed (see below), which has least
> impact on existing implementations.
>
>
>
> >(1) Allow Empty ERO to mean no path.
>
> >Let it be valid in all messages to mean that no intended path exists for
> this LSP.
>
> >As per -16,
>
> >- empty ERO is added in the end of synchronization marker (PCRpt).
>
> >- The ERO may be empty if the PCE does not have a path for a delegated
> LSP.
>
>
>
> >We can add text in section 6.2 to say something like –
>
>
>
> >The ERO may be empty if the PCE does not have an intended path for the
> delegated LSP.
>
> >If the local policy allows it, the PCC SHOULD signal the tear down of
> the LSP. At
>
> >this time, PCC MAY also revoke delegation and use a locally computed
> path instead.
>
>
>
> >To me this is more logical and in spirit with the rest of the document,
> also would require least amount of changes in existing implementations.
>
>
>
> If we have rough consensus, we should start to work on the changes  needed
> in draft-ietf-pce-stateful-pce-16 to clarify, I would propose to add the
> following sentences in somewhere in Section 6.2 (edited on top of what
> Dhruv has suggested above):
>
>
>
> The ERO may be empty if the PCE cannot find one or a set of valid paths
> for a delegated LSP.  One typical situation resulting in this empty ERO
> carried in the PCUpd message is that PCE can no longer find two strictly
> SRLG-disjoint paths for a delegation LSP after link failure.  If its local
> policy allows it, the PCC SHOULD signal the tear down of the LSP.
> Alternatively, PCC MAY revoke delegation and use a locally computed path
> instead.
>
>
>
> Does the text look good to address the ambiguity issue you raised?
>
>
>
> Regards,
>
> Xian
>
>
>
> *发件人:* Pce [mailto:pce-boun...@ietf.org] *代表 *
> stephane.litkow...@orange.com
> *发送时间:* 2016年10月6日 15:19
> *收件人:* DUGEON Olivier IMT/OLN; Aissaoui, Mustapha (Nokia - CA); MEURIC
> Julien IMT/OLN; pce@ietf.org
> *主题:* Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE
> advising PCC about no path
>
>
>
> Hi Olivier,
>
>
>
> I think we almost have a consensus on using the current ERO object with
> the semantic “I have no intended path”, so adding a new sibling object is
> not necessary.
>
> It would then be up to the PCC to have a local policy to control the
> associated behavior => tear down, revoking delegation, keep existing path
> or whatever…
>
>
>
> Optionally, we still need to agree if we consider NO-PATH object as a
> complement and optional object.
>
>
>
> Brgds,
>
>
>
>
>
> *From:* Pce [mailto:pce-boun...@ietf.org <pce-boun...@ietf.org>] *On
> Behalf Of *Olivier Dugeon
> *Sent:* Wednesday, October 05, 2016 18:11
> *To:* Aissaoui, Mustapha (Nokia - CA); MEURIC Julien IMT/OLN; pce@ietf.org
> *Subject:* Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE
> advising PCC about no path
>
>
>
> Hello all,
>
> If I try to summarize, in one hand we have some implementations that use
> an empty ERO which lead in interoperability issues due to ambiguous
> interpretation, and in the other hand a clear non-ambiguous object i.e.
> NO-PATH which break implementation or at least impose strong modifications
> in existing code.
>
> So, in order to advance on the subject, I would propose to add new code
> points to explicitly mention that the ERO is empty, and why is empty:  This
> solves the ambiguity while imposing smooth modification in today
> implementations as they just have to check a particular ERO code point (in
> replacement to check that the ERO is empty) instead processing a new object
> (i.e. NO-PATH).
>
> There is two options for this new ERO code points:
>
> a) At the ERO registry level. ERO is Class Type 20 and Class Num 1. The
> idea is to add a new Class Num = 2 i.e. Empty ERO with possibility to add
> different values to specify why it is empty e.g. 1 = NO-PATH, 2 =

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Zhangxian (Xian)]

Hi, Stephane,  Olivier, All,

  I support the option 1 Dhruv proposed (see below), which has least impact 
on existing implementations.

>(1) Allow Empty ERO to mean no path.
>Let it be valid in all messages to mean that no intended path exists for this 
>LSP.
>As per -16,
>- empty ERO is added in the end of synchronization marker (PCRpt).
>- The ERO may be empty if the PCE does not have a path for a delegated LSP.

>We can add text in section 6.2 to say something like –

>The ERO may be empty if the PCE does not have an intended path for the 
>delegated LSP.
>If the local policy allows it, the PCC SHOULD signal the tear down of the LSP. 
>At
>this time, PCC MAY also revoke delegation and use a locally computed path 
>instead.

>To me this is more logical and in spirit with the rest of the document, also 
>would require least amount of changes in existing implementations.

If we have rough consensus, we should start to work on the changes  needed in 
draft-ietf-pce-stateful-pce-16 to clarify, I would propose to add the following 
sentences in somewhere in Section 6.2 (edited on top of what Dhruv has 
suggested above):

The ERO may be empty if the PCE cannot find one or a set of valid paths for a 
delegated LSP.  One typical situation resulting in this empty ERO carried in 
the PCUpd message is that PCE can no longer find two strictly SRLG-disjoint 
paths for a delegation LSP after link failure.  If its local policy allows it, 
the PCC SHOULD signal the tear down of the LSP. Alternatively, PCC MAY revoke 
delegation and use a locally computed path instead.

Does the text look good to address the ambiguity issue you raised?

Regards,
Xian

发件人: Pce [mailto:pce-boun...@ietf.org] 代表 stephane.litkow...@orange.com
发送时间: 2016年10月6日 15:19
收件人: DUGEON Olivier IMT/OLN; Aissaoui, Mustapha (Nokia - CA); MEURIC Julien 
IMT/OLN; pce@ietf.org
主题: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC 
about no path

Hi Olivier,

I think we almost have a consensus on using the current ERO object with the 
semantic “I have no intended path”, so adding a new sibling object is not 
necessary.
It would then be up to the PCC to have a local policy to control the associated 
behavior => tear down, revoking delegation, keep existing path or whatever…

Optionally, we still need to agree if we consider NO-PATH object as a 
complement and optional object.

Brgds,


From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of Olivier Dugeon
Sent: Wednesday, October 05, 2016 18:11
To: Aissaoui, Mustapha (Nokia - CA); MEURIC Julien IMT/OLN; 
pce@ietf.org<mailto:pce@ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path


Hello all,

If I try to summarize, in one hand we have some implementations that use an 
empty ERO which lead in interoperability issues due to ambiguous 
interpretation, and in the other hand a clear non-ambiguous object i.e. NO-PATH 
which break implementation or at least impose strong modifications in existing 
code.

So, in order to advance on the subject, I would propose to add new code points 
to explicitly mention that the ERO is empty, and why is empty:  This solves the 
ambiguity while imposing smooth modification in today implementations as they 
just have to check a particular ERO code point (in replacement to check that 
the ERO is empty) instead processing a new object (i.e. NO-PATH).

There is two options for this new ERO code points:

a) At the ERO registry level. ERO is Class Type 20 and Class Num 1. The idea is 
to add a new Class Num = 2 i.e. Empty ERO with possibility to add different 
values to specify why it is empty e.g. 1 = NO-PATH, 2 = LOOSE-PATH ...

b) At the sub-object level. Within ERO Class Type 20 and Class Num 1, add new 
code points. eg. 38 = Empty-ERO NO-PATH, 39 = Empty-ERO Loose-Path ...

Option a) require to request a new registry and code points while option b) 
just require new code points in existing registry to IANA. Option a) allows to 
add a dedicated registry for Empty ERO with possibility to precisely describe 
why it is empty, while option b) mix the notion of Empty ERO and the reason why 
it is empty. Looking to implementation, option a) impose to look at Class Num 
when processing the ERO while option b) just need to look at sub-object.

Draft stateful could introduce this new ERO code points (whatever option a or 
b) and other drafts (initiated, synchronisation ...) could add there own needs 
regarding this empty ERO.

Comments are welcome.

Regards

Olivier
Le 05/10/2016 à 16:01, Aissaoui, Mustapha (Nokia - CA) a écrit :
I am of the same opinion too. Let us keep empty ERO in both the PCUpd and PCRpt 
messages to mean there is no valid path for the LSP. A PCC implementation 
receiving a PCUpd with an empty ERO for a non-zero PLSP-ID can decide if the 
outcome of this means to tear down the path or keep the existing working path. 
If the

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[stephane.litkowski]

Hi Olivier,

I think we almost have a consensus on using the current ERO object with the 
semantic “I have no intended path”, so adding a new sibling object is not 
necessary.
It would then be up to the PCC to have a local policy to control the associated 
behavior => tear down, revoking delegation, keep existing path or whatever…

Optionally, we still need to agree if we consider NO-PATH object as a 
complement and optional object.

Brgds,


From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of Olivier Dugeon
Sent: Wednesday, October 05, 2016 18:11
To: Aissaoui, Mustapha (Nokia - CA); MEURIC Julien IMT/OLN; pce@ietf.org
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path


Hello all,

If I try to summarize, in one hand we have some implementations that use an 
empty ERO which lead in interoperability issues due to ambiguous 
interpretation, and in the other hand a clear non-ambiguous object i.e. NO-PATH 
which break implementation or at least impose strong modifications in existing 
code.

So, in order to advance on the subject, I would propose to add new code points 
to explicitly mention that the ERO is empty, and why is empty:  This solves the 
ambiguity while imposing smooth modification in today implementations as they 
just have to check a particular ERO code point (in replacement to check that 
the ERO is empty) instead processing a new object (i.e. NO-PATH).

There is two options for this new ERO code points:

a) At the ERO registry level. ERO is Class Type 20 and Class Num 1. The idea is 
to add a new Class Num = 2 i.e. Empty ERO with possibility to add different 
values to specify why it is empty e.g. 1 = NO-PATH, 2 = LOOSE-PATH ...

b) At the sub-object level. Within ERO Class Type 20 and Class Num 1, add new 
code points. eg. 38 = Empty-ERO NO-PATH, 39 = Empty-ERO Loose-Path ...

Option a) require to request a new registry and code points while option b) 
just require new code points in existing registry to IANA. Option a) allows to 
add a dedicated registry for Empty ERO with possibility to precisely describe 
why it is empty, while option b) mix the notion of Empty ERO and the reason why 
it is empty. Looking to implementation, option a) impose to look at Class Num 
when processing the ERO while option b) just need to look at sub-object.

Draft stateful could introduce this new ERO code points (whatever option a or 
b) and other drafts (initiated, synchronisation ...) could add there own needs 
regarding this empty ERO.

Comments are welcome.

Regards

Olivier
Le 05/10/2016 à 16:01, Aissaoui, Mustapha (Nokia - CA) a écrit :
I am of the same opinion too. Let us keep empty ERO in both the PCUpd and PCRpt 
messages to mean there is no valid path for the LSP. A PCC implementation 
receiving a PCUpd with an empty ERO for a non-zero PLSP-ID can decide if the 
outcome of this means to tear down the path or keep the existing working path. 
If the PCC wants to use the local CSPF or an IGP driven path, then it must 
first revoke the delegation as per existing procedures.

Regards,
Mustapha.

From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of Julien Meuric
Sent: Wednesday, October 05, 2016 8:04 AM
To: pce@ietf.org<mailto:pce@ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path


Hi all,

Chair hat on, I concur with the proposed plan: we need to stick to the current 
scope of the base stateful I-D and fix pending issues in there, new proposals 
like "partial delegation" do require a new document.

Thank you Dhruv and Stéphane for being proactive on that,

Julien

Oct. 05, 2016 - :
Hi Dhruv, Sudhir

I agree that what is achieved here is a partial delegation which is not inline 
with delegation in stateful pce draft which gives full control to PCE.

The use case described is interesting but I’m afraid that empty ERO was used 
for this purpose while there was no discussion at WG level to achieve consensus 
for this partial delegation solution. I would prefer that Juniper used a vendor 
specific flag for this behavior rather than using existing objects.
I would prefer to close the base stateful PCE draft before adding new features …

Partial delegation may be complex to handle as some people may want ERO to be 
controlled by PCC while constraints by PCE and some other may want the opposite 
(constraints by PCC and ERO by PCE) so this requires more discussion.

Brgds,

Stephane

From: Dhruv Dhody [mailto:dhruv.dh...@huawei.com]
Sent: Wednesday, October 05, 2016 06:09
To: Sudhir Cheruathur; LITKOWSKI Stephane OBS/OINIS; Harish Magganmane; 
Aissaoui, Mustapha (Nokia - CA); pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Cc: 'Dhruv Dhody'
Subject: RE: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Sudhir/Harish,

Thanks for explaining your motivation but 

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Olivier Dugeon]

Hello all,

If I try to summarize, in one hand we have some implementations that use an 
empty ERO which lead in interoperability issues due to ambiguous 
interpretation, and in the other hand a clear non-ambiguous object i.e. NO-PATH 
which break implementation or at least impose strong modifications in existing 
code.

So, in order to advance on the subject, I would propose to add new code points 
to explicitly mention that the ERO is empty, and why is empty:  This solves the 
ambiguity while imposing smooth modification in today implementations as they 
just have to check a particular ERO code point (in replacement to check that 
the ERO is empty) instead processing a new object (i.e. NO-PATH).

There is two options for this new ERO code points:

a) At the ERO registry level. ERO is Class Type 20 and Class Num 1. The idea is 
to add a new Class Num = 2 i.e. Empty ERO with possibility to add different 
values to specify why it is empty e.g. 1 = NO-PATH, 2 = LOOSE-PATH ...

b) At the sub-object level. Within ERO Class Type 20 and Class Num 1, add new 
code points. eg. 38 = Empty-ERO NO-PATH, 39 = Empty-ERO Loose-Path ...

Option a) require to request a new registry and code points while option b) 
just require new code points in existing registry to IANA. Option a) allows to 
add a dedicated registry for Empty ERO with possibility to precisely describe 
why it is empty, while option b) mix the notion of Empty ERO and the reason why 
it is empty. Looking to implementation, option a) impose to look at Class Num 
when processing the ERO while option b) just need to look at sub-object.

Draft stateful could introduce this new ERO code points (whatever option a or 
b) and other drafts (initiated, synchronisation ...) could add there own needs 
regarding this empty ERO.

Comments are welcome.

Regards

Olivier

Le 05/10/2016 à 16:01, Aissaoui, Mustapha (Nokia - CA) a écrit :
>
> I am of the same opinion too. Let us keep empty ERO in both the PCUpd and 
> PCRpt messages to mean there is no valid path for the LSP. A PCC 
> implementation receiving a PCUpd with an empty ERO for a non-zero PLSP-ID can 
> decide if the outcome of this means to tear down the path or keep the 
> existing working path. If the PCC wants to use the local CSPF or an IGP 
> driven path, then it must first revoke the delegation as per existing 
> procedures.
>
>  
>
> Regards,
>
> Mustapha.
>
>  
>
> *From:*Pce [mailto:pce-boun...@ietf.org] *On Behalf Of *Julien Meuric
> *Sent:* Wednesday, October 05, 2016 8:04 AM
> *To:* pce@ietf.org
> *Subject:* Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE 
> advising PCC about no path
>
>  
>
> Hi all,
>
> Chair hat on, I concur with the proposed plan: we need to stick to the 
> current scope of the base stateful I-D and fix pending issues in there, new 
> proposals like "partial delegation" do require a new document.
>
> Thank you Dhruv and Stéphane for being proactive on that,
>
> Julien
>
>  
>
> Oct. 05, 2016 - :
>
> Hi Dhruv, Sudhir
>
>  
>
> I agree that what is achieved here is a partial delegation which is not 
> inline with delegation in stateful pce draft which gives full control to PCE.
>
>  
>
> The use case described is interesting but I’m afraid that empty ERO was 
> used for this purpose while there was no discussion at WG level to achieve 
> consensus for this partial delegation solution. I would prefer that Juniper 
> used a vendor specific flag for this behavior rather than using existing 
> objects.
>
> I would prefer to close the base stateful PCE draft before adding new 
> features …
>
>  
>
> Partial delegation may be complex to handle as some people may want ERO 
> to be controlled by PCC while constraints by PCE and some other may want the 
> opposite (constraints by PCC and ERO by PCE) so this requires more discussion.
>
>  
>
> Brgds,
>
>  
>
> Stephane
>
>  
>
> *From:*Dhruv Dhody [mailto:dhruv.dh...@huawei.com]
> *Sent:* Wednesday, October 05, 2016 06:09
> *To:* Sudhir Cheruathur; LITKOWSKI Stephane OBS/OINIS; Harish Magganmane; 
> Aissaoui, Mustapha (Nokia - CA); pce@ietf.org <mailto:pce@ietf.org>; 
> draft-ietf-pce-stateful-...@tools.ietf.org 
> <mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
> *Cc:* 'Dhruv Dhody'
> *Subject:* RE: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE 
> advising PCC about no path
>
>  
>
> Hi Sudhir/Harish,
>
>  
>
> Thanks for explaining your motivation but it is not as per the definition 
> of “delegation”.
>
> What you are suggesting is a new feature lets call it “partial 
> delegation”. I hope we can discuss the merit and t

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Aissaoui, Mustapha (Nokia - CA)]

I am of the same opinion too. Let us keep empty ERO in both the PCUpd and PCRpt 
messages to mean there is no valid path for the LSP. A PCC implementation 
receiving a PCUpd with an empty ERO for a non-zero PLSP-ID can decide if the 
outcome of this means to tear down the path or keep the existing working path. 
If the PCC wants to use the local CSPF or an IGP driven path, then it must 
first revoke the delegation as per existing procedures.

Regards,
Mustapha.

From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of Julien Meuric
Sent: Wednesday, October 05, 2016 8:04 AM
To: pce@ietf.org
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path


Hi all,

Chair hat on, I concur with the proposed plan: we need to stick to the current 
scope of the base stateful I-D and fix pending issues in there, new proposals 
like "partial delegation" do require a new document.

Thank you Dhruv and Stéphane for being proactive on that,

Julien

Oct. 05, 2016 - :
Hi Dhruv, Sudhir

I agree that what is achieved here is a partial delegation which is not inline 
with delegation in stateful pce draft which gives full control to PCE.

The use case described is interesting but I'm afraid that empty ERO was used 
for this purpose while there was no discussion at WG level to achieve consensus 
for this partial delegation solution. I would prefer that Juniper used a vendor 
specific flag for this behavior rather than using existing objects.
I would prefer to close the base stateful PCE draft before adding new features 
...

Partial delegation may be complex to handle as some people may want ERO to be 
controlled by PCC while constraints by PCE and some other may want the opposite 
(constraints by PCC and ERO by PCE) so this requires more discussion.

Brgds,

Stephane

From: Dhruv Dhody [mailto:dhruv.dh...@huawei.com]
Sent: Wednesday, October 05, 2016 06:09
To: Sudhir Cheruathur; LITKOWSKI Stephane OBS/OINIS; Harish Magganmane; 
Aissaoui, Mustapha (Nokia - CA); pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Cc: 'Dhruv Dhody'
Subject: RE: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Sudhir/Harish,

Thanks for explaining your motivation but it is not as per the definition of 
"delegation".
What you are suggesting is a new feature lets call it "partial delegation". I 
hope we can discuss the merit and the procedures of this in a small separate 
document away from this base document. IMHO this document should explain why 
partial delegation is needed and especially why PCE would still like to control 
how the path is computed at PCC?

How do you/WG feel about taking this approach?

Regards,
Dhruv


From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of Sudhir Cheruathur
Sent: 04 October 2016 23:16
To: stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>; Harish 
Magganmane <hmagganm...@juniper.net<mailto:hmagganm...@juniper.net>>; Aissaoui, 
Mustapha (Nokia - CA) 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>; 
pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Stephane/Dhruv/Mustapha,

>>I'm trying to understand what you really want to achieve here. Or do you want 
>>to have PCE updating LSP parameters/constraints but let the PCC compute path ?

We want to allow changing of other attributes of an LSP (such as BW/metric), 
but leave the path computation to the PCC. With this a PCC now has a choice to 
do a local CSPF or use IGP hop-by-hop. This choice can be enforced on the PCC 
with an empty ERO and local policy. When we want to drive this same behavior 
from the PCE then we could you use a NO-PATH object.

We could define flags in the NO-PATH object to tell the PCC what to do when a 
path is not available. The Nature of Issue is set to 0 (No path) and flags can 
be defined to specify the following

a)  Bring down the LSP

b)  Use local CSPF

c)   Use IGP based hop-by-hop.

Thanks
Redgs
Sudhir C



From: Pce <pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>> on behalf of 
"stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>" 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>
Date: Monday, October 3, 2016 at 1:27 AM
To: Harish Magganmane 
<hmagganm...@juniper.net<mailto:hmagganm...@juniper.net>>, "Aissaoui, Mustapha 
(Nokia - CA)" 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>, 
"pce@ietf.org<mailto:pce@ietf.org>" <pce@ietf.org<mailto:pce@ietf.org>>, 
"draft-ietf-pce-stateful-...@tools.ietf.or

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Julien Meuric]

  
  
Hi all,
  
  Chair hat on, I concur with the proposed plan: we need to stick to
  the current scope of the base stateful I-D and fix pending issues
  in there, new proposals like "partial delegation" do require a new
  document.
  
  Thank you Dhruv and Stéphane for being proactive on that,
  
  Julien


Oct. 05, 2016 - :


  
  
  
  
  
Hi Dhruv,
Sudhir
 
I agree that
what is achieved here is a partial delegation which is not
inline with delegation in stateful pce draft which gives
full control to PCE.
 
The use case
described is interesting but I’m afraid that empty ERO was
used for this purpose while there was no discussion at WG
level to achieve consensus for this partial delegation
solution. I would prefer that Juniper used a vendor specific
flag for this behavior rather than using existing objects.
I would prefer
to close the base stateful PCE draft before adding new
features …
 
Partial
delegation may be complex to handle as some people may want
ERO to be controlled by PCC while constraints by PCE and
some other may want the opposite (constraints by PCC and ERO
by PCE) so this requires more discussion.
 
Brgds,
 
Stephane
 

  
From:
Dhruv Dhody [mailto:dhruv.dh...@huawei.com]

Sent: Wednesday, October 05, 2016 06:09
To: Sudhir Cheruathur; LITKOWSKI Stephane
OBS/OINIS; Harish Magganmane; Aissaoui, Mustapha (Nokia
- CA); pce@ietf.org;
draft-ietf-pce-stateful-...@tools.ietf.org
Cc: 'Dhruv Dhody'
    Subject: RE: [Pce] Urgent issue with
    draft-ietf-pce-stateful-pce : PCE advising PCC about no
    path
  

 
Hi
Sudhir/Harish,

 
Thanks
for explaining your motivation but it is not as per the
definition of “delegation”.

What
you are suggesting is a new feature lets call it “partial
delegation”. I hope we can discuss the merit and the
procedures of this in a small separate document away from
this base document. IMHO this document should explain why
partial delegation is needed and especially why PCE would
still like to control how the path is computed at PCC?

 
How
do you/WG feel about taking this approach?

 
Regards,
Dhruv
 
 

  
From: Pce [mailto:pce-boun...@ietf.org]
On Behalf Of Sudhir Cheruathur
Sent: 04 October 2016 23:16
To: stephane.litkow...@orange.com;
Harish Magganmane <hmagganm...@juniper.net>;
Aissaoui, Mustapha (Nokia - CA) <mustapha.aissa...@nokia.com>;
pce@ietf.org;

  draft-ietf-pce-stateful-...@tools.ietf.org
                Subject: Re: [Pce] Urgent issue with
        draft-ietf-pce-stateful-pce : PCE advising PCC about no
path
  

 
Stephane/Dhruv/Mustapha,
 
>>I’m
trying to understand what you really want to achieve here.
Or do you want to have PCE updating LSP
parameters/constraints but let the PCC compute path ?
 
We want to
allow changing of other attributes of an LSP (such as
BW/metric), but leave the path computation to the PCC. With
this a PCC now has a choice to do a local CSPF or use IGP
hop-by-hop. This choice can be enforced on the PCC with an
empty ERO and local policy. When we want to drive this same
behavior from the PCE then we could you use a NO-PATH
object.
 
We could
define flags in the NO-PATH object to tell the PCC what to
do when a path is not available. The Nature of Issue is set
to 0 (No path) and flags can be defined to specify the
following 
a) 
  Bring
down the LSP
b) 
  Use
local CSPF
c)  
  Use
IGP based hop-by-hop.
 
Thanks
Redgs
Sudhir C
 
 
 

  From:
  Pce <pce-boun...@ietf.org> on behalf of "stephane.litkow...@orange.com" <stephane.litkow...@orange.com>
  

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Robert Varga]

On 10/03/2016 04:30 PM, Dhruv Dhody wrote:
> (1) Allow Empty ERO to mean no path.
> 
> Let it be valid in all messages to mean that no intended path exists for
> this LSP.
> 
> As per -16,
> 
> - empty ERO is added in the end of synchronization marker (PCRpt). 
> 
> - The ERO may be empty if the PCE does not have a path for a delegated LSP.
> 
>  
> 
> We can add text in section 6.2 to say something like –
> 
>  
> 
> The ERO may be empty if the PCE does not have an intended path for the
> delegated LSP. 
> 
> If the local policy allows it, the PCC SHOULD signal the tear down of
> the LSP. At 
> 
> this time, PCC MAY also revoke delegation and use a locally computed
> path instead. 
> 
>  
> 
> To me this is more logical and in spirit with the rest of the document,
> also would require least amount of changes in existing implementations.

+1

Thanks,
Robert



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Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[stephane.litkowski]

Hi Dhruv, Sudhir

I agree that what is achieved here is a partial delegation which is not inline 
with delegation in stateful pce draft which gives full control to PCE.

The use case described is interesting but I’m afraid that empty ERO was used 
for this purpose while there was no discussion at WG level to achieve consensus 
for this partial delegation solution. I would prefer that Juniper used a vendor 
specific flag for this behavior rather than using existing objects.
I would prefer to close the base stateful PCE draft before adding new features …

Partial delegation may be complex to handle as some people may want ERO to be 
controlled by PCC while constraints by PCE and some other may want the opposite 
(constraints by PCC and ERO by PCE) so this requires more discussion.

Brgds,

Stephane

From: Dhruv Dhody [mailto:dhruv.dh...@huawei.com]
Sent: Wednesday, October 05, 2016 06:09
To: Sudhir Cheruathur; LITKOWSKI Stephane OBS/OINIS; Harish Magganmane; 
Aissaoui, Mustapha (Nokia - CA); pce@ietf.org; 
draft-ietf-pce-stateful-...@tools.ietf.org
Cc: 'Dhruv Dhody'
Subject: RE: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Sudhir/Harish,

Thanks for explaining your motivation but it is not as per the definition of 
“delegation”.
What you are suggesting is a new feature lets call it “partial delegation”. I 
hope we can discuss the merit and the procedures of this in a small separate 
document away from this base document. IMHO this document should explain why 
partial delegation is needed and especially why PCE would still like to control 
how the path is computed at PCC?

How do you/WG feel about taking this approach?

Regards,
Dhruv


From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of Sudhir Cheruathur
Sent: 04 October 2016 23:16
To: stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>; Harish 
Magganmane <hmagganm...@juniper.net<mailto:hmagganm...@juniper.net>>; Aissaoui, 
Mustapha (Nokia - CA) 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>; 
pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Stephane/Dhruv/Mustapha,

>>I’m trying to understand what you really want to achieve here. Or do you want 
>>to have PCE updating LSP parameters/constraints but let the PCC compute path ?

We want to allow changing of other attributes of an LSP (such as BW/metric), 
but leave the path computation to the PCC. With this a PCC now has a choice to 
do a local CSPF or use IGP hop-by-hop. This choice can be enforced on the PCC 
with an empty ERO and local policy. When we want to drive this same behavior 
from the PCE then we could you use a NO-PATH object.

We could define flags in the NO-PATH object to tell the PCC what to do when a 
path is not available. The Nature of Issue is set to 0 (No path) and flags can 
be defined to specify the following

a)  Bring down the LSP

b)  Use local CSPF

c)   Use IGP based hop-by-hop.

Thanks
Redgs
Sudhir C



From: Pce <pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>> on behalf of 
"stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>" 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>
Date: Monday, October 3, 2016 at 1:27 AM
To: Harish Magganmane 
<hmagganm...@juniper.net<mailto:hmagganm...@juniper.net>>, "Aissaoui, Mustapha 
(Nokia - CA)" 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>, 
"pce@ietf.org<mailto:pce@ietf.org>" <pce@ietf.org<mailto:pce@ietf.org>>, 
"draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>"
 
<draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Harish,

Thanks for your feedback.
I do not really understand why you map the empty ERO to a decision to possibly 
fallback computation to local.
As you mentioned, it could be a local PCC policy decision and this local policy 
could be to tear down the LSP instead of deferring ERO selection to the local 
router as you proposed.

The important point is the semantic of this empty ERO, not really the action 
taken. I understand in your email  that you still interpret it from a semantic 
point of view has an indication of no path, so you then can decide to defer ERO 
selection to the router. Because in the case, you want to have the PCE giving 
back path computation role to PCC, the PCE must use the delegate flag for this 
purpose and can revoke the delegation at anytime. I’m trying to understand what 
you really want to achieve here. 

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Dhruv Dhody]

Hi Sudhir/Harish,

Thanks for explaining your motivation but it is not as per the definition of 
“delegation”.
What you are suggesting is a new feature lets call it “partial delegation”. I 
hope we can discuss the merit and the procedures of this in a small separate 
document away from this base document. IMHO this document should explain why 
partial delegation is needed and especially why PCE would still like to control 
how the path is computed at PCC?

How do you/WG feel about taking this approach?

Regards,
Dhruv

From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of Sudhir Cheruathur
Sent: 04 October 2016 23:16
To: stephane.litkow...@orange.com; Harish Magganmane <hmagganm...@juniper.net>; 
Aissaoui, Mustapha (Nokia - CA) <mustapha.aissa...@nokia.com>; pce@ietf.org; 
draft-ietf-pce-stateful-...@tools.ietf.org
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Stephane/Dhruv/Mustapha,

>>I’m trying to understand what you really want to achieve here. Or do you want 
>>to have PCE updating LSP parameters/constraints but let the PCC compute path ?

We want to allow changing of other attributes of an LSP (such as BW/metric), 
but leave the path computation to the PCC. With this a PCC now has a choice to 
do a local CSPF or use IGP hop-by-hop. This choice can be enforced on the PCC 
with an empty ERO and local policy. When we want to drive this same behavior 
from the PCE then we could you use a NO-PATH object.

We could define flags in the NO-PATH object to tell the PCC what to do when a 
path is not available. The Nature of Issue is set to 0 (No path) and flags can 
be defined to specify the following

a)  Bring down the LSP

b)  Use local CSPF

c)   Use IGP based hop-by-hop.

Thanks
Redgs
Sudhir C



From: Pce <pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>> on behalf of 
"stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>" 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>
Date: Monday, October 3, 2016 at 1:27 AM
To: Harish Magganmane 
<hmagganm...@juniper.net<mailto:hmagganm...@juniper.net>>, "Aissaoui, Mustapha 
(Nokia - CA)" 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>, 
"pce@ietf.org<mailto:pce@ietf.org>" <pce@ietf.org<mailto:pce@ietf.org>>, 
"draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>"
 
<draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Harish,

Thanks for your feedback.
I do not really understand why you map the empty ERO to a decision to possibly 
fallback computation to local.
As you mentioned, it could be a local PCC policy decision and this local policy 
could be to tear down the LSP instead of deferring ERO selection to the local 
router as you proposed.

The important point is the semantic of this empty ERO, not really the action 
taken. I understand in your email  that you still interpret it from a semantic 
point of view has an indication of no path, so you then can decide to defer ERO 
selection to the router. Because in the case, you want to have the PCE giving 
back path computation role to PCC, the PCE must use the delegate flag for this 
purpose and can revoke the delegation at anytime. I’m trying to understand what 
you really want to achieve here. Or do you want to have PCE updating LSP 
parameters/constraints but let the PCC compute path ?

Best Regards,

Stephane



From: Harish Magganmane [mailto:hmagganm...@juniper.net]
Sent: Saturday, October 01, 2016 00:53
To: LITKOWSKI Stephane OBS/OINIS; Aissaoui, Mustapha (Nokia - CA); 
pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Stephane,

We are not in favor of using empty ERO as way to signal the tearing of an LSP. 
IMO empty ERO object should be interpreted to mean deferring the ERO selection 
to the router, perhaps through local policy on the PCC. For example PCC could 
choose between a local CSPF or a IGP based hop-by-hop.

In cases where we want PCE to explicitly control the behavior of the PCC when a 
path is not available, NO-PATH object can be used to dictate the behavior. One 
such behavior could be that of tearing down the LSP.

Thanks,
Harish

From: Pce <pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>> on behalf of 
"stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>" 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>
Date: Friday, September 30, 2016 at 8:33 AM
To: "Aissaoui

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Sudhir Cheruathur]

Stephane/Dhruv/Mustapha,

>>I’m trying to understand what you really want to achieve here. Or do you want 
>>to have PCE updating LSP parameters/constraints but let the PCC compute path ?

We want to allow changing of other attributes of an LSP (such as BW/metric), 
but leave the path computation to the PCC. With this a PCC now has a choice to 
do a local CSPF or use IGP hop-by-hop. This choice can be enforced on the PCC 
with an empty ERO and local policy. When we want to drive this same behavior 
from the PCE then we could you use a NO-PATH object.

We could define flags in the NO-PATH object to tell the PCC what to do when a 
path is not available. The Nature of Issue is set to 0 (No path) and flags can 
be defined to specify the following

a)   Bring down the LSP

b)   Use local CSPF

c)   Use IGP based hop-by-hop.

Thanks
Redgs
Sudhir C



From: Pce <pce-boun...@ietf.org> on behalf of "stephane.litkow...@orange.com" 
<stephane.litkow...@orange.com>
Date: Monday, October 3, 2016 at 1:27 AM
To: Harish Magganmane <hmagganm...@juniper.net>, "Aissaoui, Mustapha (Nokia - 
CA)" <mustapha.aissa...@nokia.com>, "pce@ietf.org" <pce@ietf.org>, 
"draft-ietf-pce-stateful-...@tools.ietf.org" 
<draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Harish,

Thanks for your feedback.
I do not really understand why you map the empty ERO to a decision to possibly 
fallback computation to local.
As you mentioned, it could be a local PCC policy decision and this local policy 
could be to tear down the LSP instead of deferring ERO selection to the local 
router as you proposed.

The important point is the semantic of this empty ERO, not really the action 
taken. I understand in your email  that you still interpret it from a semantic 
point of view has an indication of no path, so you then can decide to defer ERO 
selection to the router. Because in the case, you want to have the PCE giving 
back path computation role to PCC, the PCE must use the delegate flag for this 
purpose and can revoke the delegation at anytime. I’m trying to understand what 
you really want to achieve here. Or do you want to have PCE updating LSP 
parameters/constraints but let the PCC compute path ?

Best Regards,

Stephane



From: Harish Magganmane [mailto:hmagganm...@juniper.net]
Sent: Saturday, October 01, 2016 00:53
To: LITKOWSKI Stephane OBS/OINIS; Aissaoui, Mustapha (Nokia - CA); 
pce@ietf.org; draft-ietf-pce-stateful-...@tools.ietf.org
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Stephane,

We are not in favor of using empty ERO as way to signal the tearing of an LSP. 
IMO empty ERO object should be interpreted to mean deferring the ERO selection 
to the router, perhaps through local policy on the PCC. For example PCC could 
choose between a local CSPF or a IGP based hop-by-hop.

In cases where we want PCE to explicitly control the behavior of the PCC when a 
path is not available, NO-PATH object can be used to dictate the behavior. One 
such behavior could be that of tearing down the LSP.

Thanks,
Harish

From: Pce <pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>> on behalf of 
"stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>" 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>
Date: Friday, September 30, 2016 at 8:33 AM
To: "Aissaoui, Mustapha (Nokia - CA)" 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>, 
"pce@ietf.org<mailto:pce@ietf.org>" <pce@ietf.org<mailto:pce@ietf.org>>, 
"draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>"
 
<draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Mustapha,

Your proposal works from my point of view, but it looks that it causes some 
trouble to another vendor so I would like these people (and others as well) to 
express their concerns regarding usage of empty ERO.

Thanks for pointing again your last proposal.

Best Regards,

Stephane


From: Aissaoui, Mustapha (Nokia - CA) [mailto:mustapha.aissa...@nokia.com]
Sent: Friday, September 30, 2016 17:08
To: LITKOWSKI Stephane OBS/OINIS; pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: RE: Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC 
about no path

Hi Stephane,
In the last email related to this issue, I made a proposal to Olivier and 
Robert commented on it. Would that be sufficient to address this interop issue?
https://mail

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Aissaoui, Mustapha (Nokia - CA)]

Hi Harish,
The intended use of the empty ERO is to indicate there is no valid path for the 
LSP. In fact, if you read the updated Section 6.1 in the latest version of the 
draft Ina posted, we are proposing to use this not just in the PCUpd message 
but also in the PCRpt message if PCC did not have a valid path for an LSP it 
has control of.

Perhaps where I do agree with you is that PCC could make use of a policy to 
decide if the LSP should be torn down or it would be kept on the current 
working path even if PCE by sending the empty ERO is telling there exists no 
path which satisfied the constraints of that LSP.

Regards,
Mustapha.

From: Dhruv Dhody [mailto:dhruv.dh...@huawei.com]
Sent: Monday, October 03, 2016 10:30 AM
To: stephane.litkow...@orange.com; Harish Magganmane; Aissaoui, Mustapha (Nokia 
- CA); pce@ietf.org; draft-ietf-pce-stateful-...@tools.ietf.org
Subject: RE: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Stephane,

The case you described is valid and important to support. I am one of those who 
believed empty ERO to be just fine, but I understand the other point of view as 
well.
IMHO we need to resolve it quickly and completely.  I see two ways -

(1) Allow Empty ERO to mean no path.
Let it be valid in all messages to mean that no intended path exists for this 
LSP.
As per -16,
- empty ERO is added in the end of synchronization marker (PCRpt).
- The ERO may be empty if the PCE does not have a path for a delegated LSP.

We can add text in section 6.2 to say something like -

The ERO may be empty if the PCE does not have an intended path for the 
delegated LSP.
If the local policy allows it, the PCC SHOULD signal the tear down of the LSP. 
At
this time, PCC MAY also revoke delegation and use a locally computed path 
instead.

To me this is more logical and in spirit with the rest of the document, also 
would require least amount of changes in existing implementations.

(2) Add NO-PATH object
If we do this way, then we need to make following changes in all messages!


-Remove ERO as mandatory object and its error codes in all messages

-Change RBNF to add NO-PATH object

-Update NI fields (if needed)

All existing implementation would need change, and this change would be a 
non-backward-compatible change. This is what I am afraid of the most especially 
with open source. But if this is the only way to reach consensus and move the 
document forward, I *personally* could live with it.

Hi Harish

I agree with Stephane we have returning/revoking of delegation as the right 
mechanism for PCC to select the locally computed path instead.
Do you have suggestion to improve the text above if we go with option 1?

Regards,
Dhruv


From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of 
stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>
Sent: 03 October 2016 13:58
To: Harish Magganmane 
<hmagganm...@juniper.net<mailto:hmagganm...@juniper.net>>; Aissaoui, Mustapha 
(Nokia - CA) <mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>; 
pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Harish,

Thanks for your feedback.
I do not really understand why you map the empty ERO to a decision to possibly 
fallback computation to local.
As you mentioned, it could be a local PCC policy decision and this local policy 
could be to tear down the LSP instead of deferring ERO selection to the local 
router as you proposed.

The important point is the semantic of this empty ERO, not really the action 
taken. I understand in your email  that you still interpret it from a semantic 
point of view has an indication of no path, so you then can decide to defer ERO 
selection to the router. Because in the case, you want to have the PCE giving 
back path computation role to PCC, the PCE must use the delegate flag for this 
purpose and can revoke the delegation at anytime. I'm trying to understand what 
you really want to achieve here. Or do you want to have PCE updating LSP 
parameters/constraints but let the PCC compute path ?

Best Regards,

Stephane



From: Harish Magganmane [mailto:hmagganm...@juniper.net]
Sent: Saturday, October 01, 2016 00:53
To: LITKOWSKI Stephane OBS/OINIS; Aissaoui, Mustapha (Nokia - CA); 
pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Stephane,

We are not in favor of using empty ERO as way to signal the tearing of an LSP. 
IMO empty ERO object should be interpreted to mean deferring the ERO selection 
to the router, perhaps through local policy on the PCC. For example PCC could 

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Dhruv Dhody]

Hi Stephane,

The case you described is valid and important to support. I am one of those who 
believed empty ERO to be just fine, but I understand the other point of view as 
well.
IMHO we need to resolve it quickly and completely.  I see two ways -

(1) Allow Empty ERO to mean no path.
Let it be valid in all messages to mean that no intended path exists for this 
LSP.
As per -16,
- empty ERO is added in the end of synchronization marker (PCRpt).
- The ERO may be empty if the PCE does not have a path for a delegated LSP.

We can add text in section 6.2 to say something like -

The ERO may be empty if the PCE does not have an intended path for the 
delegated LSP.
If the local policy allows it, the PCC SHOULD signal the tear down of the LSP. 
At
this time, PCC MAY also revoke delegation and use a locally computed path 
instead.

To me this is more logical and in spirit with the rest of the document, also 
would require least amount of changes in existing implementations.

(2) Add NO-PATH object
If we do this way, then we need to make following changes in all messages!


-Remove ERO as mandatory object and its error codes in all messages

-Change RBNF to add NO-PATH object

-Update NI fields (if needed)

All existing implementation would need change, and this change would be a 
non-backward-compatible change. This is what I am afraid of the most especially 
with open source. But if this is the only way to reach consensus and move the 
document forward, I *personally* could live with it.

Hi Harish

I agree with Stephane we have returning/revoking of delegation as the right 
mechanism for PCC to select the locally computed path instead.
Do you have suggestion to improve the text above if we go with option 1?

Regards,
Dhruv


From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of 
stephane.litkow...@orange.com
Sent: 03 October 2016 13:58
To: Harish Magganmane <hmagganm...@juniper.net>; Aissaoui, Mustapha (Nokia - 
CA) <mustapha.aissa...@nokia.com>; pce@ietf.org; 
draft-ietf-pce-stateful-...@tools.ietf.org
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Harish,

Thanks for your feedback.
I do not really understand why you map the empty ERO to a decision to possibly 
fallback computation to local.
As you mentioned, it could be a local PCC policy decision and this local policy 
could be to tear down the LSP instead of deferring ERO selection to the local 
router as you proposed.

The important point is the semantic of this empty ERO, not really the action 
taken. I understand in your email  that you still interpret it from a semantic 
point of view has an indication of no path, so you then can decide to defer ERO 
selection to the router. Because in the case, you want to have the PCE giving 
back path computation role to PCC, the PCE must use the delegate flag for this 
purpose and can revoke the delegation at anytime. I'm trying to understand what 
you really want to achieve here. Or do you want to have PCE updating LSP 
parameters/constraints but let the PCC compute path ?

Best Regards,

Stephane



From: Harish Magganmane [mailto:hmagganm...@juniper.net]
Sent: Saturday, October 01, 2016 00:53
To: LITKOWSKI Stephane OBS/OINIS; Aissaoui, Mustapha (Nokia - CA); 
pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Stephane,

We are not in favor of using empty ERO as way to signal the tearing of an LSP. 
IMO empty ERO object should be interpreted to mean deferring the ERO selection 
to the router, perhaps through local policy on the PCC. For example PCC could 
choose between a local CSPF or a IGP based hop-by-hop.

In cases where we want PCE to explicitly control the behavior of the PCC when a 
path is not available, NO-PATH object can be used to dictate the behavior. One 
such behavior could be that of tearing down the LSP.

Thanks,
Harish

From: Pce <pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>> on behalf of 
"stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>" 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>
Date: Friday, September 30, 2016 at 8:33 AM
To: "Aissaoui, Mustapha (Nokia - CA)" 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>, 
"pce@ietf.org<mailto:pce@ietf.org>" <pce@ietf.org<mailto:pce@ietf.org>>, 
"draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>"
 
<draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Mustapha,

Your proposal works from my point of 

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[stephane.litkowski]

Hi Harish,

Thanks for your feedback.
I do not really understand why you map the empty ERO to a decision to possibly 
fallback computation to local.
As you mentioned, it could be a local PCC policy decision and this local policy 
could be to tear down the LSP instead of deferring ERO selection to the local 
router as you proposed.

The important point is the semantic of this empty ERO, not really the action 
taken. I understand in your email  that you still interpret it from a semantic 
point of view has an indication of no path, so you then can decide to defer ERO 
selection to the router. Because in the case, you want to have the PCE giving 
back path computation role to PCC, the PCE must use the delegate flag for this 
purpose and can revoke the delegation at anytime. I'm trying to understand what 
you really want to achieve here. Or do you want to have PCE updating LSP 
parameters/constraints but let the PCC compute path ?

Best Regards,

Stephane



From: Harish Magganmane [mailto:hmagganm...@juniper.net]
Sent: Saturday, October 01, 2016 00:53
To: LITKOWSKI Stephane OBS/OINIS; Aissaoui, Mustapha (Nokia - CA); 
pce@ietf.org; draft-ietf-pce-stateful-...@tools.ietf.org
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Stephane,

We are not in favor of using empty ERO as way to signal the tearing of an LSP. 
IMO empty ERO object should be interpreted to mean deferring the ERO selection 
to the router, perhaps through local policy on the PCC. For example PCC could 
choose between a local CSPF or a IGP based hop-by-hop.

In cases where we want PCE to explicitly control the behavior of the PCC when a 
path is not available, NO-PATH object can be used to dictate the behavior. One 
such behavior could be that of tearing down the LSP.

Thanks,
Harish

From: Pce <pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>> on behalf of 
"stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>" 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>
Date: Friday, September 30, 2016 at 8:33 AM
To: "Aissaoui, Mustapha (Nokia - CA)" 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>, 
"pce@ietf.org<mailto:pce@ietf.org>" <pce@ietf.org<mailto:pce@ietf.org>>, 
"draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>"
 
<draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Mustapha,

Your proposal works from my point of view, but it looks that it causes some 
trouble to another vendor so I would like these people (and others as well) to 
express their concerns regarding usage of empty ERO.

Thanks for pointing again your last proposal.

Best Regards,

Stephane


From: Aissaoui, Mustapha (Nokia - CA) [mailto:mustapha.aissa...@nokia.com]
Sent: Friday, September 30, 2016 17:08
To: LITKOWSKI Stephane OBS/OINIS; pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: RE: Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC 
about no path

Hi Stephane,
In the last email related to this issue, I made a proposal to Olivier and 
Robert commented on it. Would that be sufficient to address this interop issue?
https://mailarchive.ietf.org/arch/msg/pce/A1ADiw6Uvjn1ETjErqzgjdjXnsE

Mustapha.

From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of 
stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>
Sent: Friday, September 30, 2016 5:46 AM
To: pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC 
about no path

Hi WG, and draft authors,

We still have an urgent interoperability issue to solve with 
draft-ietf-pce-stateful-pce. We currently have no clear semantic for the PCE to 
advise the PCC that there is no more path available. This point was already 
raised through the list but as we need an URGENT resolution of this issue 
because of implementation timelines, I would like to reactivate the thread.

The situation of no path at PCE side can happen in many situations, and a 
particular situation will require PCC to tear down an existing path : let's 
think about two strictly SRLG disjoint LSPs with a working path . Now the 
transmission topology is changing (rerouting at WDM layer) leading SRLG 
disjointness not being fitted anymore and PCE cannot find anymore disjoint 
path, it must advise one PCC to tear down the path because it is no more 
disjoint (strict disjointness required).
We do not have any clear semantic today and some implementations are using 
e

Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Harish Magganmane]

Hi Stephane,

We are not in favor of using empty ERO as way to signal the tearing of an LSP. 
IMO empty ERO object should be interpreted to mean deferring the ERO selection 
to the router, perhaps through local policy on the PCC. For example PCC could 
choose between a local CSPF or a IGP based hop-by-hop.

In cases where we want PCE to explicitly control the behavior of the PCC when a 
path is not available, NO-PATH object can be used to dictate the behavior. One 
such behavior could be that of tearing down the LSP.

Thanks,
Harish

From: Pce <pce-boun...@ietf.org<mailto:pce-boun...@ietf.org>> on behalf of 
"stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>" 
<stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>>
Date: Friday, September 30, 2016 at 8:33 AM
To: "Aissaoui, Mustapha (Nokia - CA)" 
<mustapha.aissa...@nokia.com<mailto:mustapha.aissa...@nokia.com>>, 
"pce@ietf.org<mailto:pce@ietf.org>" <pce@ietf.org<mailto:pce@ietf.org>>, 
"draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>"
 
<draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>>
Subject: Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising 
PCC about no path

Hi Mustapha,

Your proposal works from my point of view, but it looks that it causes some 
trouble to another vendor so I would like these people (and others as well) to 
express their concerns regarding usage of empty ERO.

Thanks for pointing again your last proposal.

Best Regards,

Stephane


From: Aissaoui, Mustapha (Nokia - CA) [mailto:mustapha.aissa...@nokia.com]
Sent: Friday, September 30, 2016 17:08
To: LITKOWSKI Stephane OBS/OINIS; pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: RE: Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC 
about no path

Hi Stephane,
In the last email related to this issue, I made a proposal to Olivier and 
Robert commented on it. Would that be sufficient to address this interop issue?
https://mailarchive.ietf.org/arch/msg/pce/A1ADiw6Uvjn1ETjErqzgjdjXnsE

Mustapha.

From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of 
stephane.litkow...@orange.com<mailto:stephane.litkow...@orange.com>
Sent: Friday, September 30, 2016 5:46 AM
To: pce@ietf.org<mailto:pce@ietf.org>; 
draft-ietf-pce-stateful-...@tools.ietf.org<mailto:draft-ietf-pce-stateful-...@tools.ietf.org>
Subject: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC 
about no path

Hi WG, and draft authors,

We still have an urgent interoperability issue to solve with 
draft-ietf-pce-stateful-pce. We currently have no clear semantic for the PCE to 
advise the PCC that there is no more path available. This point was already 
raised through the list but as we need an URGENT resolution of this issue 
because of implementation timelines, I would like to reactivate the thread.

The situation of no path at PCE side can happen in many situations, and a 
particular situation will require PCC to tear down an existing path : let’s 
think about two strictly SRLG disjoint LSPs with a working path . Now the 
transmission topology is changing (rerouting at WDM layer) leading SRLG 
disjointness not being fitted anymore and PCE cannot find anymore disjoint 
path, it must advise one PCC to tear down the path because it is no more 
disjoint (strict disjointness required).
We do not have any clear semantic today and some implementations are using 
empty ERO for this purpose in PCUpdate but the PCC does not recognize it as a 
valid no path significance.

This subject is critical and I would like that we can achieve a consensus asap 
on the target solution so then vendors can align implementations.
This thread is focusing on the PCE -> PCC way, but having a semantic of 
reporting a no path is also necessary in PCC->PCE way through PCRpt, at least 
to ACK a PCupdate.

One of the previous discussion on the list talked about the possibility to use 
NO-PATH object which already has this semantic for PCReq/PCRep but as already 
mentioned we need to assess impact on existing implementations, so vendor 
feedback (with customer implementations) is highly required. So this is my 
starting proposal to initiate the discussion.


Best Regards,


[Orange logo]<http://www.orange.com/>

Stephane Litkowski
Network Architect
Orange/SCE/EQUANT/OINIS/NET
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Re: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC about no path

[Aissaoui, Mustapha (Nokia - CA)]

Hi Stephane,
In the last email related to this issue, I made a proposal to Olivier and 
Robert commented on it. Would that be sufficient to address this interop issue?
https://mailarchive.ietf.org/arch/msg/pce/A1ADiw6Uvjn1ETjErqzgjdjXnsE

Mustapha.

From: Pce [mailto:pce-boun...@ietf.org] On Behalf Of 
stephane.litkow...@orange.com
Sent: Friday, September 30, 2016 5:46 AM
To: pce@ietf.org; draft-ietf-pce-stateful-...@tools.ietf.org
Subject: [Pce] Urgent issue with draft-ietf-pce-stateful-pce : PCE advising PCC 
about no path

Hi WG, and draft authors,

We still have an urgent interoperability issue to solve with 
draft-ietf-pce-stateful-pce. We currently have no clear semantic for the PCE to 
advise the PCC that there is no more path available. This point was already 
raised through the list but as we need an URGENT resolution of this issue 
because of implementation timelines, I would like to reactivate the thread.

The situation of no path at PCE side can happen in many situations, and a 
particular situation will require PCC to tear down an existing path : let's 
think about two strictly SRLG disjoint LSPs with a working path . Now the 
transmission topology is changing (rerouting at WDM layer) leading SRLG 
disjointness not being fitted anymore and PCE cannot find anymore disjoint 
path, it must advise one PCC to tear down the path because it is no more 
disjoint (strict disjointness required).
We do not have any clear semantic today and some implementations are using 
empty ERO for this purpose in PCUpdate but the PCC does not recognize it as a 
valid no path significance.

This subject is critical and I would like that we can achieve a consensus asap 
on the target solution so then vendors can align implementations.
This thread is focusing on the PCE -> PCC way, but having a semantic of 
reporting a no path is also necessary in PCC->PCE way through PCRpt, at least 
to ACK a PCupdate.

One of the previous discussion on the list talked about the possibility to use 
NO-PATH object which already has this semantic for PCReq/PCRep but as already 
mentioned we need to assess impact on existing implementations, so vendor 
feedback (with customer implementations) is highly required. So this is my 
starting proposal to initiate the discussion.


Best Regards,


[Orange logo]

Stephane Litkowski
Network Architect
Orange/SCE/EQUANT/OINIS/NET
Orange Expert Future Networks
phone: +33 2 23 28 49 83 

mobile: +33 6 37 86 97 52 

stephane.litkow...@orange.com


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