Hi Tarek,

In addition to what Dhruv has said, I don’t believe 
draft-ietf-idr-segment-routing-te-policy provides a way to encode “Protocol 
Origin”, “Originator ASN” and “Originator Address”. These are essential for 
reporting existing policies from the PCC to the PCE.

Thanks,
Mike.

From: Dhruv Dhody <[email protected]>
Sent: Wednesday, March 20, 2019 11:14 AM
To: Tarek Saad <[email protected]>
Cc: [email protected]; [email protected]
Subject: Re: [Pce] Comment on draft-barth-pce-segment-routing-policy-cp

Hi Tarek,

As a individual WG member, I think reusing BGP sub-TLV in PCEP in this case(*) 
is problematic, mainly because -

(1) PCEP already has some other objects and TLVs which were defined much before 
the BGP SR Policy work, such as -
- SR-ERO subobject to carry SID (compared to BGP's Segment sub-TLV)
- TE-PATH-BINDING TLV for BSID (compared to BGP's Binding SID sub-TLV)

(2) PCEP has a very specific format for all its TLVs as per 
https://tools.ietf.org/html/rfc5440#section-7.1, you would notice that BGP does 
not follow that.

(3) SR-POLICY is a top level container, in PCEP-SR for each LSP (or candidate 
path) we carry its associated Policy information in the ASSOCIATION object.

That said, it is important that fields and encoding are aligned between BGP and 
PCEP and I would request the authors to make sure that is the case.

Thanks!
Dhruv

(*) We were able to do this successfully in case of Flowspec

On Tue, Mar 19, 2019 at 1:12 AM Tarek Saad 
<[email protected]<mailto:[email protected]>> wrote:
Hi authors,

The I-D “draft-ietf-idr-segment-routing-te-policy” defines sub-tlvs for SR 
Policy attributes that are carried in BGP (see below) for SR policy and its 
attributes. Ideally, with PCEP can achieve what is supported with BGP signaling 
and hence can leverage the most of those definitions? Is there a reason not to?



     
2.4<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2..4>.
  SR Policy Sub-TLVs  . . . . . . . . . . . . . . . . . . .   
9<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#page-9>

       
2.4.1<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2.4.1>.
  Preference Sub-TLV  . . . . . . . . . . . . . . . . .   
9<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#page-9>

       
2.4.2<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2.4.2>.
  Binding SID Sub-TLV . . . . . . . . . . .. . . . . . .  
10<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#page-10>

       
2.4.3<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2.4.3>.
  Segment List Sub-TLV  . . . . . . . . . . . . . . . .  
11<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#page-11>

       
2.4.3.1<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2.4.3.1>.
  Weight Sub-TLV

       
2.4.3.2<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2.4.3.2>.
  Segment Sub-TLV

       
2.4.4<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2.4.4>.
  Explicit NULL Label Policy Sub-TLV  . . . . . . . . .  
27<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#page-27>

       
2.4.5<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2.4.5>.
  Policy Priority Sub-TLV . . . . . . . . .. . . . . . .  
28<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#page-28>

       
2.4.6<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#section-2.4.6>.
  Policy Name Sub-TLV . . . . . . . . . . .. . . . . . .  
29<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#page-29>


Regards,
Tarek
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