Hi Dhruv,
Thanks for your reply!
I will take your suggestion for the new version. But I have two concerns.
The PSID is defined as "SRv6 Path Segment Identifier" in
draft-ietf-spring-srv6-path-segment and it is not mentioned in this documents ,
cause path segment should cover both SR-MPLS and SRv6. So I suggest we still
use the path segment instead of PSID.
Another concern is that, for example, when we put multiple path segment TLVs
in multiple PATH-ATTRIB objects but none in LSP object in PCInitiate message,
we also need to indicate PCE or egress PCC to allocate the path segment. There
may be two options, reusing P flag in LSP object to indicate all path segment
TLVs or creating a new P flag in PATH-ATTRIB object to indicate each path
segment TLV. So I think we need to clarify it.
What is your thoughts? Thanks!
Best Regards,
Quan
Original
From: DhruvDhody <dhruv.i...@gmail.com>
To: Cheng Li <c.l=40huawei....@dmarc.ietf.org>;
Cc: 熊泉00091065;pce@ietf.org
<pce@ietf.org>;draft-ietf-pce-sr-path-segm...@ietf.org
<draft-ietf-pce-sr-path-segm...@ietf.org>;
Date: 2024年09月20日 20:15
Subject: Re: [Pce] Re: Path segment supporting multiple segment lists in a
candidate path
Hi Cheng, Quan,
On Fri, Sep 20, 2024 at 2:52 PM Cheng Li <c.l=40huawei....@dmarc.ietf.org>
wrote:
Hi Quan,
Thank you for proposing the text. Please see my comment below.
Thanks,
Cheng
4.5. Path Attributes Object
The Path Attributes (PATH-ATTRIB) Object is used to carry per-path
information and to act as a separator between several ERO/RRO objects
as per [I-D.ietf-pce-multipath].
As per [RFC9545], a Path Segment can be used to uniquely identify a
segment list or multiple segment lists in a candidate path or an SR
policy.
__OLD__
When a set of path segments are used to identify multiple
segment lists, the Path Segment TLV as described in the
Section 4.2.1, MUST be carried in the PATH-ATTRIB Object to indicate
the per-SR-path information regarding the Path Segment identifier.
__OLD__
[Cheng]This might be rephrased. My suggestion.
When multiple ERO/RRO objects are included as per [I-D.ietf-pce-multipath], to
support multiple segment lists in an Candidate Path [ref to SR policy draft],
the Path Segment TLV as described in the Section 4.2.1, MUST be carried in the
PATH-ATTRIB Object to identify each SR path associated with a segment list.
Dhruv: This use of MUST here means that if a PATH-ATTRIB Object exists, the
Path Segment TLV MUST be encoded in it. But we want to do that only in case
when a different PSID is used by each segment list.
The P flag in LSP Object is used to indicate that the allocation of all path
segments need to be done by the PCE. A Path Segment TLV encoded in the LSP
Object apply to all the ERO/RRO, while a Path Segment TLV encoded in a
PATH-ATTRIB Object only apply to its ERO. In the cases that all the segment
lists are sharing a same PSID, the Path Segment TLV can be carried in the LSP
Object or each PATH-ATTRIB Object, respectively.
Dhruv: I am unsure why we need to highlight the P flag here. The rest of the
text makes sense if we set or unset the P flag.
Here is my suggestion -
The [I-D.ietf-pce-multipath] defines the PATH-ATTRIB object, which carries
per-path information and serves as a separator between multiple ERO/RRO
objects, enabling the encoding of multiple segment lists in a Candidate Path,
as described in [I-D.ietf-pce-segment-routing-policy-cp]. The Path Segment TLV
can be optionally included in the PATH-ATTRIB object to associate a segment
list with the PSID. It’s important to note that the Path Segment TLV in the
PATH-ATTRIB object applies to the path (the immediately following ERO/RRO),
whereas the Path Segment TLV in the LSP object applies to all paths in the PCEP
message. If the PSID is encoded in the PATH-ATTRIB object, it MUST be used to
identify the SR path.
Thanks!
Dhruv
From: xiong.q...@zte.com.cn <xiong.q...@zte.com.cn>
Sent: Friday, September 20, 2024 10:59 AM
To: pce@ietf.org
Cc: draft-ietf-pce-sr-path-segm...@ietf.org
Subject: Path segment supporting multiple segment lists in a candidate path
Hi PCE WG,
A new version has been submitted as per
https://www.ietf.org/archive/id/draft-ietf-pce-sr-path-segment-11.txt.
But in case of supporting multiple segment lists in a candidate path, it is
required to add Path Segment TLV into Path Attributes Object as different path
segment may identify different segment list . And in order to make it backward
compatible to current implementation, it needs to allow carrying the TLV in
both LSP and PATH-ATTRIB object. So I suggest to add a new section to describe
this part of extension as following shown.
4.5. Path Attributes Object
The Path Attributes (PATH-ATTRIB) Object is used to carry per-path
information and to act as a separator between several ERO/RRO objects
as per [I-D.ietf-pce-multipath].
As per [RFC9545], a Path Segment can be used to uniquely identify a
segment list or multiple segment lists in a candidate path or an SR
policy. When a set of path segments are used to identify multiple
segment lists, the Path Segment TLV as described in the
Section 4.2.1, MUST be carried in the PATH-ATTRIB Object to indicate
the per-SR-path information regarding the Path Segment identifier.
The P flag in LSP Object is used to indicate that the allocation of
all path segments need to be done by the PCE. When one single path
segment is used to identify all segment lists, the Path Segment TLV
MAY be carried in the LSP Object or PATH-ATTRIB Object. But the Path
Segment TLV MUST be ignored in the LSP Object when it is also
included in the PATH-ATTRIB Object.
What is your thoughts? Any comments and suggestions are welcome. Thanks!
Best Regards,
Quan
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