On 02/04/18 14:19 , Acee Lindem (acee) wrote:
Speaking as WG member:
I couldn’t agree more with Ketan. No changes are required to these
documents.
as a coauthor of the OSPF/OSPFv3 SR drafts, I fully agree.
thanks,
Peter
Thanks,
Acee
*From: *Lsr <lsr-boun...@ietf.org> on behalf of "Ketan Talaulikar
(ketant)" <ket...@cisco.com>
*Date: *Monday, April 2, 2018 at 7:36 AM
*To: *Aijun Wang <wangai...@tsinghua.org.cn>
*Cc: *"lsr@ietf.org" <lsr@ietf.org>
*Subject: *Re: [Lsr] Inconsistence regarding the definition of "Adj-SID
Sub-TLV" between OSPF and ISIS extension for Segment Routing
Hi Aijun,
I understand what you are referring to now, but these are not
inconsistencies. ISIS, OSPF and BGP-LS are 3 different protocols. Their
encodings may not all be the same. ISIS uses 1 byte for type/length and
has LSP space constraints which you would notice in the protocol
encodings. OSPF doesn’t have the same challenge and you would notice how
its TLVs tend to be aligned. BGP-LS is somewhat similar to OSPF from
these size constraints perspective.
I do not see the implementation challenges in encoding from the two IGPs
into BGP-LS. It does not make sense to change any of the protocol
encodings that you ask for currently since implementations have been
shipping with them for many years.
IMHO it is not necessary to put such constraints for what you call
“consistency” on these 3 protocol encodings in the future. However, we
do try to be consistent in semantics as much as possible.
Thanks,
Ketan
*From:*Aijun Wang <wangai...@tsinghua.org.cn>
*Sent:* 02 April 2018 16:52
*To:* Ketan Talaulikar (ketant) <ket...@cisco.com>
*Cc:* lsr@ietf.org
*Subject:* Re: [Lsr] Inconsistence regarding the definition of "Adj-SID
Sub-TLV" between OSPF and ISIS extension for Segment Routing
Hi, Ketan:
There is one two-bytes “Reserved” field in “Adjacency Segment
Identifier” TLV for OSPF extension, but this field doesn’t exist in the
corresponding TLV for ISIS extension. Every other fields are same.
Corresponding definition in BGP-LS is similar with OSPF(not similar with
ISIS as I mentioned in previous mail). Then when the router
reports/redistributes the ISIS LSDB information to BGP protocol, the
router must add two bytes to the “length” field and add/stuff the
“reserved” field; but for OSPF LSDB, the router need only copy the
corresponding fields according.
We have found the error arises from this inconsistency from the real
router and think it is better to align this definition in different IGP
protocol.
Update to ISIS related extensions draft may be easier.
Aijun Wang
China Telecom
在 2018年4月2日，18:26，Ketan Talaulikar (ketant)
<ket...@cisco.com<mailto:ket...@cisco.com>> 写道：
Hi Aijun,
Can you clarify what you mean by “inconsistencies”?
Also, you are referring the old version of OSPFv3 SR draft before it
was aligned with the OSPFv2 SR draft. Please check
https://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-routing-extensions-11#section-6.1
OSPF and ISIS are different protocols and there are some differences
between them. I would not call them inconsistencies. BGP-LS spec
refers to the individual IGP drafts for interpretation of flags. So
please specifically point out what inconsistency you are referring to.
Thanks,
Ketan
*From:*Lsr <lsr-boun...@ietf.org<mailto:lsr-boun...@ietf.org>> *On
Behalf Of *Aijun Wang
*Sent:* 02 April 2018 14:23
*To:* lsr@ietf.org<mailto:lsr@ietf.org>
*Subject:* [Lsr] Inconsistence regarding the definition of "Adj-SID
Sub-TLV" between OSPF and ISIS extension for Segment Routing
Hi, All:
We found there were some inconsistences for the definition of
“Adjacency Segment Identifier” between OSPF and ISIS extension for
segment routing, please see the link below for comparison.
https://tools.ietf.org/html/draft-ietf-isis-segment-routing-extensions-15#section-2.2.1
https://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-routing-extensions-10#section-7.1
Here we want to know is there any reason for this inconsistence? We
think this inconsistence can easily cause error for BGP-LS
implementation for segment routing extension, as that defined in
https://tools.ietf.org/html/draft-ietf-idr-bgp-ls-segment-routing-ext-04#section-2.2.1,
which is similar with ISIS extension for SR, but different from OSPF
extension for SR.
Do we need to make them consistent? It seems change the definition
in OSPF extension may be less influence for the existing related drafts.
Best Regards.
Aijun Wang
Network R&D and Operation Support Department
China Telecom Corporation Limited Beijing Research
Institute,Beijing, China.
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