Re: [spring] [mpls] FW: New Version Notification for draft-bryant-mpls-unified-ip-sr-01.txt

[Robert Raszuk <[e-mail]>]

Hi Adrian,

I see few so to say "challenges" with the proposal

A)

SRv6 SID is 128 bits where first 64 is the locator and remaining 64 is the
function. So to "emulate" this directly with SR-MPLS you need for 1 SRv6
SID stack of 8 labels ! And some use cases of SRv6 already talk about using
few SRv6 SIDs. Please show me the today's hardware which can consume in
single pass and make sense of stack of say 32 mpls labels ... so here goes
your "interchangeability".

B)

One of serious concerns with SRH insertion in transit as expressed by 6man
was MTU. How does this proposal solves this at all if what you are doing
here is taking nicely MTU discovered and negotiated IPv6 packet and adding
mpls stack or tower + UDP + IPv/v6 encap to it ? How would end hosts now
will get any awareness about this ?

C)

One of the very nice applications for SRv6 is spray function with full
multicast address transparency. Please kindly elaborate how are you going
to map IPv4 or IPv6 multicast addresses into MPLS labels ?

- - -

I think while it looks great on slides that now we will have two different
ways to do SR on IP networks if you really focus to specific applications
you will find a lot of them which are not going to be compatible with your
proposal. So maybe instead trying to squeeze the balloon to fit the bottle
we better collectively focus on making the balloon fly ?

Kind regards,
Robert.






On Fri, Aug 11, 2017 at 8:53 PM, Adrian Farrel <[e-mail]> wrote:

> All,
>
> The presentation of this draft in Prague seemed to be well received and we
> got
> some comments that we have stated to act on in this revision.
>
> One, non-technical request was to share the work with the SPRING working
> group,
> and I have just done that.
>
> At the meeting I noted that...
> > The authors think this is in charter for MPLS
> > But polish and discussion is needed before we ask for adoption
>
> As this polish continues, I'd like to ask the list what they think of this
> work.
> Is it going in the right direction? Is it work that you support?
>
> Thanks,
> Adrian
>
> > ________________________________________
> > From: [e-mail]
> > Sent: 11 August 2017 19:39:59 (UTC+00:00) Dublin, Edinburgh, Lisbon,
> London
> > To: Stewart Bryant; John E Drake; Adrian Farrel
> > Subject: New Version Notification for draft-bryant-mpls-unified-ip-
> sr-01.txt
> >
> > A new version of I-D, draft-bryant-mpls-unified-ip-sr-01.txt
> > has been successfully submitted by Adrian Farrel and posted to the
> > IETF repository.
> >
> > Name:           draft-bryant-mpls-unified-ip-sr
> > Revision:       01
> > Title:          A Unified Approach to IP Segment Routing
> > Document date:  2017-08-11
> > Group:          Individual Submission
> > Pages:          16
> > URL:
> https://www.ietf.org/internet-drafts/draft-bryant-mpls-unified-ip-sr-
> > 01.txt
> > Status:
> https://datatracker.ietf.org/doc/draft-bryant-mpls-unified-ip-sr/
> > Htmlized:       https://tools.ietf.org/html/
> draft-bryant-mpls-unified-ip-sr-01
> > Htmlized:
> https://datatracker.ietf.org/doc/html/draft-bryant-mpls-unified-ip-
> > sr-01
> > Diff:
> https://www.ietf.org/rfcdiff?url2=draft-bryant-mpls-unified-ip-sr-01
> >
> > Abstract:
> >    Segment routing is a source routed forwarding method that allows
> >    packets to be steered through a network on paths other than the
> >    shortest path derived from the routing protocol.  The approach uses
> >    information encoded in the packet header to partially or completely
> >    specify the route the packet takes through the network, and does not
> >    make use of a signaling protocol to pre-install paths in the network.
> >
> >    Two different encapsulations have been defined to enable segment
> >    routing in an MPLS network and in an IPv6 network.  While
> >    acknowledging that there is a strong need to support segment routing
> >    in both environments, this document defines a converged, unified
> >    approach to segment routing that enables a single mechanism to be
> >    applied in both types of network.  The resulting approach is also
> >    applicable to IPv4 networks without the need for any changes to the
> >    IPv4 specification.
> >
> >    This document makes no changes to the segment routing architecture
> >    and builds on existing protocol mechanisms such as the encapsulation
> >    of MPLS within UDP defined in RFC 7510.
> >
> >    No new procedures are introduced, but existing mechanisms are
> >    combined to achieve the desired result.
> >
> >
> >
> >
> >
> > 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.
> >
> > The IETF Secretariat
>
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