Subject: lianghebing35 Test Question About Path Selection in SFC

From: wbkeix <[email-masked]>
Date: Wed, 7 Feb 2018 18:17:54 +0800 (CST)

Hi Adrian,

Thanks for your detailed specification!O(∩_∩)O~ Your reply is exactly 
what I want to express. 

I suggest to define a B flag for the SRP in PCInitiate message too. Hope 
PCE-GMPLS draft could take it into consideration.

And thanks Dhruv for the help!O(∩_∩)O~

Best Regards,
Quan 

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Re: [Pce] 答复: Re: A question about RFC8281 PCE-initiated LSPs.

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To: Farrel Adrian <adrian at olddog.co.uk> 
Subject: Re: [Pce] 答复: Re: A question about RFC8281 PCE-initiated LSPs. 
From: Dhruv Dhody <dhruv.ietf at gmail.com> 
Date: Wed, 24 Jan 2018 21:30:43 +0530 
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Thanks Adrian! This makes sense! Hope the authors of GMPLS draft could 
take this up. 

Regards,
Dhruv

On Wed, Jan 24, 2018 at 9:06 PM, Adrian Farrel <adrian at olddog.co.uk> 
wrote:

So, I think Quan is asking how to use a PCInitiate message to cause the 
creation of a "co-routed" bidirectional LSP that is achieved in the 
signaling plane by a single Path/Resv exchange.

That is *G*MPLS function, but an answer would still be useful.

Now, on a PCReq you need the B-bit to tell the PCE to compute a 
bidirectional path. But what you should be looking at is the PCRep 
message. That is, how does the PCE indicate that a bidirectional path has 
been returned? And the answer is two points:

1. Since the requester asked for a bidirectional path, and since a path 
has been computed, the PCC has every right to assume that the path can be 
used for a bidirectional LSP.

2. The RP Object is present on the PCRep and also contains thee B-flag.

Now, note that the PCInitiate most closely follows the PCRep. That is, it 
flows from PCE to PCC and indicates the path of the LSP to be set up.

Now, the PCInitiate carries the SRP Object, not the RP Object (just like 
PCUpd message).

There is a flags field in the SRP Object, but the only bit defined is in 
8281 for LSP removal.

So, to expand on Quan's question: how do we Update an LSP that was set up 
with the B-flag in the RP object, and how do we create an bidirectional 
LSP using PCInitiate message?

It is fine if the answer is "This is GMPLS function that possibly should 
not have been in 5440, and we need to look at some additional work for 
GMPLS extensions for 8231 and 8281."

draft-ietf-pce-pcep-stateful-pce-gmpls is a starting point and should, 
perhaps, define a B flag for the SRP on the PCUpd that would then also be 
available automatically on the PCInitiate.

Yours ramblingly,

Adrian

 

From: Pce [mailto:pce-bounces at ietf.org] On Behalf Of xiong.quan at 
zte.com.cn
Sent: 24 January 2018 09:21
To: dhruv.dhody at huawei.com
Cc: robert.varga at pantheon.tech; draft-barth-pce-association-bidir at 
ietf.org; hu.fangwei at relay.zte.com.cn; msiva at cisco.com; pce at 
ietf.org; edward.crabbe at gmail.com
Subject: [Pce] 答复: Re: A question about RFC8281 PCE-initiated LSPs.

Hi Dhruv, 

I agree PCInitiate message including the ASSOCIATION Object may create a 
new LSP. 

But it still need to create bi-directional LSP by two messages. 

In some scenario, like PTN, we need to establish a bi-directional LSP by 
one message of a PCE request. 

In my opinion, this is the requirement to create a bi-directional LSP by a 
 PCInitiate message. 

Thanks, 
Quan 

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Re: [Pce] A question about RFC8281 PCE-initiated LSPs. 

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To: "xiong.quan at zte.com.cn" <xiong.quan at zte.com.cn>, 
"draft-barth-pce-association-bidir at ietf.org" 
<draft-barth-pce-association-bidir at ietf.org> 
Subject: Re: [Pce] A question about RFC8281 PCE-initiated LSPs. 
From: Dhruv Dhody <dhruv.dhody at huawei.com> 
Date: Tue, 23 Jan 2018 11:21:15 +0000 
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Thread-topic: [Pce] A question about RFC8281 PCE-initiated LSPs. 

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Hi Quan, 

As per [1]: 
       A PCE initiating a new LSP, can include the association group 
   information.  This is done by including the ASSOCIATION Object in a 

   PCInitiate message. 

So when a new LSP is created by PCE, you could still indicate the 
association. The association is not limited to existing LSPs. 

Hope this helps! Let me know if I understood your question correctly! 

Regards, 

Dhruv 

[1] 
https://tools.ietf.org/html/draft-ietf-pce-association-group-04#section-5.2.1 

From: xiong.quan at zte.com.cn [mailto:xiong.quan at zte.com.cn] 
Sent: 23 January 2018 13:07 
To: Dhruv Dhody <dhruv.dhody at huawei.com>; 
draft-barth-pce-association-bidir at ietf.org 
Cc: edward.crabbe at gmail.com; inaminei at google.com; msiva at 
cisco.com; robert.varga at pantheon.tech; pce at ietf.org; hu.fangwei at 
relay.zte.com.cn; julien.meuric at orange.com; jonathan.hardwick at 
metaswitch.com 
Subject: Re: [Pce] A question about RFC8281 PCE-initiated LSPs. 

Hi Dhruv, 

Thank you for the reply!O(∩_∩)O~ 

I agree two created PCE-initiated LSPs may be associated by ASSOCIATION 
object as discussed in draft-barth-pce-association-bidir. 

But if there is no LSP existed, how to request a bi-directional TE LSP 
from PCE in PCE initiated operation? 

Quan Xiong 

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Re: [Pce] A question about RFC8281 PCE-initiated LSPs. 

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To: "xiong.quan at zte.com.cn" <xiong.quan at zte.com.cn>, "edward.crabbe 
at gmail.com" <edward.crabbe at gmail.com>, "inaminei at google.com" 
<inaminei at google.com>, "msiva at cisco.com" <msiva at cisco.com>, 
"robert.varga at pantheon.tech" <robert.varga at pantheon.tech> 
Subject: Re: [Pce] A question about RFC8281 PCE-initiated LSPs. 
From: Dhruv Dhody <dhruv.dhody at huawei.com> 
Date: Tue, 23 Jan 2018 03:28:27 +0000 
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Thread-topic: [Pce] A question about RFC8281 PCE-initiated LSPs. 

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Hi Quan, 

Check out -  
https://datatracker.ietf.org/doc/draft-barth-pce-association-bidir/ 

Authors are in cc, if you need to have further discussion! 

Thanks! 

Dhruv 

From: Pce [mailto:pce-bounces at ietf.org] On Behalf Of xiong.quan at 
zte.com.cn 
Sent: 23 January 2018 07:37 
To: edward.crabbe at gmail.com; inaminei at google.com; msiva at 
cisco.com; robert.varga at pantheon.tech 
Cc: hu.fangwei at relay.zte.com.cn; pce at ietf.org 
Subject: [Pce] A question about RFC8281 PCE-initiated LSPs. 

Hi all, 

I encountered a problem as following shown.O(∩_∩)O~ 

As defined in RFC5440,the PCC-initiated LSPs creation uses the B bit in RP 
object of PCReq message to indicate the direction of the TE LSP. 
When set, the PCC requests a bi-directional TE LSP and when cleared, the 
TE LSP is unidirectional. 

And in stateful PCE, RFC8281 proposed the PCE-initiated LSPs and the PCE 
could send a PCInitiate message to the PCC to request the creation of an 
LSP. 
The PCInitiate message carry the Objects including SRP, LSP ,END-POINTS 
and ERO. But no B bit in SRP object. 

How to configure the direction of the TE LSP in PCE-initiated operation? 

Best Regards, 

Quan Xiong 

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