Re: [Pce] WG Last Call for draft-ietf-pce-binding-label-sid-07 (and Code Point Allocation)

"Chengli (Cheng Li)" <> Fri, 26 March 2021 02:46 UTC

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From: "Chengli (Cheng Li)" <>
To: Aijun Wang <>, "" <>, "" <>
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Thread-Topic: [Pce] WG Last Call for draft-ietf-pce-binding-label-sid-07 (and Code Point Allocation)
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Date: Fri, 26 Mar 2021 02:46:08 +0000
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Subject: Re: [Pce] WG Last Call for draft-ietf-pce-binding-label-sid-07 (and Code Point Allocation)
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Hi Aijun,

Many thanks for your comments! Please see my reply inline. The diff is attached.


-----Original Message-----
From: Aijun Wang [] 
Sent: Monday, March 22, 2021 11:57 AM
Subject: RE: [Pce] WG Last Call for draft-ietf-pce-binding-label-sid-07 (and Code Point Allocation)


1. The concept of PCC requests the allocating of BSID for a LSP is clear, but the scenario that PCE allocate the BSID is not convincible. 
  PCE can request the PCC to allocate the BSID for one LSP. It should not allocate the value directly. 

[Cheng]Section 8 is optionally used when PCE is in control of label space (PCECC) and would not be used for vanilla stateful PCE.

2. What's the reason to include the BT=3, that is "SRv6 Endpoint Behavior and SID Structure"? It is one general information and not close connection to the normal usage of BSID. 
[Cheng] This is an alignment with other SIDs. In order to support backward compatibility, we want to remain BT2, and introduce a new BT for support SID structure. It can be used for future use case.

3. Will it be more clear to define one new bit(R bit) within the Flag field of "TE-PATH-BINDING TLV" to indicate clearly the remove of BSID allocation to a LSP? Instead of the implicit method that depending on the presence of TE-PATH-BINDING TLV as described in current draft? 
[Cheng] It is possible. But there are existing implementations that would get impacted.

4. For BT=0, the length is set to 7. How to skip the padding trailing zeros to a 4-octet boundary when parsing?
[Cheng] We have updated the description of BT=0 as per Adrian's comment. Length=7 and handling of padding is as per RFC5440: 

   The Length field defines the length of the value portion in bytes.
   The TLV is padded to 4-bytes alignment; padding is not included in
   the Length field (so a 3-byte value would have a length of 3, but the
   total size of the TLV would be 8 bytes).

Best Regards

Aijun Wang
China Telecom

-----Original Message-----
From: <> On Behalf Of
Sent: Thursday, March 18, 2021 7:09 PM
Subject: [Pce] WG Last Call for draft-ietf-pce-binding-label-sid-07 (and Code Point Allocation)

Hi all,

This message initiates a 2-week PCE WG Last Call for draft-ietf-pce-binding-label-sid-07. Please review and share your feedback, whatever it is, using the PCE mailing list. This WGLC will end on Thursday April 1st (no kidding).

Moreover, we have received a request from the authors for a code point allocation to support interoperability testing.

RFC 7120 requires to meet the following criteria to proceed:

b. The format, semantics, processing, and other rules related to handling the protocol entities defined by the code points (henceforth called
"specifications") must be adequately described in an Internet-Draft.
c. The specifications of these code points must be stable; i.e., if there is a change, implementations based on the earlier and later specifications must be seamlessly interoperable.

If anyone believes that the draft does not meet these criteria, or believes that early allocation is not appropriate for any other reason, please send an email to the PCE mailing list explaining why. If the chairs hear no objections by Thursday, March 25th, we will kick off the "early" allocation request.


Dhruv & Julien


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