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

["Adrian Farrel" <[e-mail]>]

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:[e-mail]] On Behalf Of [e-mail]
Sent: 24 January 2018 09:21
To: [e-mail]
Cc: [e-mail]; [e-mail];
[e-mail]; [e-mail]; [e-mail]; edward.crabbe@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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ietf.org" <pce at ietf.org>, "hu.fangwei at relay.zte.com.cn" <hu.fangwei at
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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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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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