Re: I-D Action: draft-ietf-isis-segment-routing-extensions-13.txt

Stefano,
 
Among the changes between draft-ietf-isis-segment-routing-extensions-12 and -13 is the removal of the SID/Label sub-TLV from the SID/Label Binding TLV.
 
I don't agree with this change.  The SID/Label sub-TLV is used in the SID/Label Binding TLV when the Mirror Context flag is set in the SID/Label Binding TLV.  The use of the Mirroring Context Segment is described in section 5 of draft-ietf-spring-segment-routing-12.  There is at least one implementation using the encoding described in the versions of the draft up to and including draft-ietf-isis-segment-routing-extensions-12, where the SID/Label sub-TLV carries the label information for the mirror context in the SID/Label Binding TLV.  The SID/Label sub-TLV has the appropriate characteristics for this application.
 
I also noticed a separate issue in that the IANA considerations section (both before and after the changes in -13) does not capture the use of the SID/Label Sub-TLV in the SR Local Block Sub-TLV.  Presumably when the SID/Label Sub-TLV is used in the SR Local Block Sub-TLV, its type is the same as when it is used in the SID/Label Binding TLV and the Multi-Topology Segment Identifier / Label Binding TLV.  If so, this should be reflected in the definition of the new sub-TLV registry.
 
Thanks,
Chris


-----Original Message-----
From: Isis-wg [mailto:[email protected]] On Behalf Of Stefano Previdi (sprevidi)
Sent: Monday, June 19, 2017 10:27 PM
To: [email protected] list <[email protected]>
Subject: Re: [Isis-wg] I-D Action: draft-ietf-isis-segment-routing-extensions-13.txt

All,

in tis version we removed the ERO subTLVs of the Binding SID TLV and fixed some other minor inconsistencies.

Thanks.
s.


> On Jun 19, 2017, at 10:25 PM, [email protected] wrote:
> 
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the IS-IS for IP Internets of the IETF.
> 
>        Title           : IS-IS Extensions for Segment Routing
>        Authors         : Stefano Previdi
>                          Clarence Filsfils
>                          Ahmed Bashandy
>                          Hannes Gredler
>                          Stephane Litkowski
>                          Bruno Decraene
>                          Jeff Tantsura
> 	Filename        : draft-ietf-isis-segment-routing-extensions-13.txt
> 	Pages           : 33
> 	Date            : 2017-06-19
> 
> Abstract:
>   Segment Routing (SR) allows for a flexible definition of end-to-end
>   paths within IGP topologies by encoding paths as sequences of
>   topological sub-paths, called "segments".  These segments are
>   advertised by the link-state routing protocols (IS-IS and OSPF).
> 
>   This draft describes the necessary IS-IS extensions that need to be
>   introduced for Segment Routing operating on an MPLS data-plane.
> 
> 
> 
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-ietf-isis-segment-routing-exten
> sions/
> 
> There are also htmlized versions available at:
> https://tools.ietf.org/html/draft-ietf-isis-segment-routing-extensions
> -13
> https://datatracker.ietf.org/doc/html/draft-ietf-isis-segment-routing-
> extensions-13
> 
> A diff from the previous version is available at:
> https://www.ietf.org/rfcdiff?url2=draft-ietf-isis-segment-routing-exte
> nsions-13
> 
> 
> Please note that it may take a couple of minutes from the time of 
> submission until the htmlized version and diff are available at tools.ietf.org.
> 
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
> 
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