Hi Dhruv,
Thanks for the reply. I understand your point; however, my concern is not so
much on the PCEP protocol object definition, but more on the attribute(s)
alignment for the different protocol cases.
I’ll quote an example you gave for BSID TLV definition in both drafts..
draft-ietf-idr-segment-routing-te-policy defines “S”, and “I” flags but those
are missing from draft-sivabalan-pce-binding-label-sid
* S-Flag: This flag encodes the "Specified-BSID-only" behavior.
It is used by SRPM as described in section 6.2.3 in
[I-D.ietf-spring-segment-routing-policy<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#ref-I-D.ietf-spring-segment-routing-policy>].
* I-Flag: This flag encodes the "Drop Upon Invalid" behavior. It
is used by SRPM as described in section 8.2 in
[I-D.ietf-spring-segment-routing-policy<https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05#ref-I-D.ietf-spring-segment-routing-policy>].
Similarly, draft-sivabalan-pce-binding-label-sid defines BT=0/1 behaviors but
those are missing from the other draft..
There may be other cases for SR-ERO too – e.g. missing “SR Algorithm”, etc.
I noticed a trend in LSR WG to define sub-TLVs that can be resused by multiple
IGP protocols (e.g. the sub-TLVs defined in
draft-ietf-lsr-pce-discovery-security-support).. and I was wondering if this
approach could be leveraged here too.
Regards,
Tarek
From: Dhruv Dhody <[email protected]>
Date: Wednesday, March 20, 2019 at 11:14 AM
To: Tarek Saad <[email protected]>
Cc: "[email protected]"
<[email protected]>, "[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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