Re: [Lsr] Mirja Kühlewind's No Objection on draft-ietf-isis-segment-routing-extensions-24: (with COMMENT)

["Les Ginsberg (ginsberg)" <[e-mail]>]

Gyan -

The paragraph you cut and pasted is providing a short overview of Segment Routing, which can be used on two different data planes - IPv6 and MPLS. 

The introduction goes on to say:

"This draft describes the necessary IS-IS extensions that need to be
   introduced for Segment Routing operating on an MPLS data-plane."

An MPLS dataplane supports forwarding of both IPv4 and IPv6 packets - and the document makes that clear throughout.

Extensions for IS-IS to support Segment Routing over an IPv6 dataplane are described in https://datatracker.ietf.org/doc/draft-bashandy-isis-srv6-extensions/ .

   Les

> -----Original Message-----
> From: Lsr <[e-mail]> On Behalf Of Gyan Mishra
> Sent: Tuesday, May 14, 2019 7:09 PM
> To: Mirja Kühlewind <[e-mail]>
> Cc: [e-mail]; Christian Hopps
> <[e-mail]>; [e-mail];
> [e-mail]; [e-mail]; The IESG <[e-mail]>;
> [e-mail]
> Subject: Re: [Lsr] Mirja Kühlewind's No Objection on draft-ietf-isis-segment-
> routing-extensions-24: (with COMMENT)
> 
> 
> I noticed in the intro that IPv4 is not mentioned just IPv6 and mpls.  Was that
> on purpose.
> 
>    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).
>    Prefix segments represent an ECMP-aware shortest-path to a prefix (or
>    a node), as per the state of the IGP topology.  Adjacency segments
>    represent a hop over a specific adjacency between two nodes in the
>    IGP.  A prefix segment is typically a multi-hop path while an
>    adjacency segment, in most of the cases, is a one-hop path.  SR’s
>    control-plane can be applied to both IPv6 and MPLS data-planes, and
>    does not require any additional signaling (other than the regular
>    IGP).  For example, when used in MPLS networks, SR paths do not
>    require any LDP or RSVP-TE signaling.  Still, SR can interoperate in
>    the presence of LSPs established with RSVP or LDP.
> 
> Gyan Mishra
> Verizon Communications
> Phone: [phone]
> 
> Sent from my iPhone
> 
> > On May 14, 2019, at 7:58 AM, Mirja Kühlewind via Datatracker
> <[e-mail]> wrote:
> >
> > Mirja Kühlewind has entered the following ballot position for
> > draft-ietf-isis-segment-routing-extensions-24: No Objection
> >
> > When responding, please keep the subject line intact and reply to all
> > email addresses included in the To and CC lines. (Feel free to cut this
> > introductory paragraph, however.)
> >
> >
> > Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
> > for more information about IESG DISCUSS and COMMENT positions.
> >
> >
> > The document, along with other ballot positions, can be found here:
> > https://datatracker.ietf.org/doc/draft-ietf-isis-segment-routing-
> extensions/
> >
> >
> >
> > ----------------------------------------------------------------------
> > COMMENT:
> > ----------------------------------------------------------------------
> >
> > A few comments/questions:
> >
> > 1) For both the Prefix Segment Identifier and the Adjacency Segment
> Identifier
> > sub-TLV it is not fully clear to me what the value field is used for when the
> > V-Flag is set. Can you further elaborate this in the draft or provide a
> > respective pointer?
> >
> > 2) The F-Flag in Adjacency Segment Identifier sub-TLV and SID/Label
> Binding TLV
> > is only one bit. I'm not expecting a new version of IP any time soon,
> however,
> > maybe completely different address families could be useful as well. Not
> sure
> > if only 1 bit is future-proof...?
> >
> > 3) Would it make sense to also discuss any risk of leaking information (e.g.
> > about the network topology) in the security consideration section?
> >
> >
> > _______________________________________________
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> 
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