Subject: Status BOF in Berlin

From: Stewart Bryant <[email-masked]>
Date: Thu, 20 Jun 2013 20:06:50 +0100

STATUS

  * Name: Stacked Tunnels for Source Routing (STATUS) [Was TUBAS]
  * Status: Approved
  * Description

    The IETF has two packet-based forwarding technologies: IP and MPLS.

    IP previously had a source-based routing mechanism made available
    through an IP Option. This mechanism has, however, not been widely
    used and has a number of issues that make its use inadvisable, and
    other mechanisms (such as RFC 1940
    <http://tools.ietf.org/html/rfc1940>) do not appear to have been
    implemented at all.

    The ability of a router to influence or control the forwarding path
    of an individual packet or all the packets of a given Forwarding
    Equivalence Class (FEC) is a desirable feature for a number of
    reasons including Label Switched Path stitching, egress protection,
    explicit routing, egress ASBR link selection, and backup (bypass
    tunnels, Remote Loop-Free Alternates) routing. This can be achieved
    by facilitating source-initiated selection of routes to complement
    the route selection provided by existing routing protocols for both
    inter- domain and intra-domain routes.

    Historically, distribution of MPLS label binding information was
    done by relying on label distribution protocols such as LDP and
    RSVP-TE.

    Several new proposals have been made to make use of the MPLS
    forwarding plane in novel but backward-compatible ways, and to
    install forwarding instructions using information distributed by the
    IGP running in the network, or through the management plane. It has
    been suggested that similar mechanisms might also be applied in IPv6.

    This BoF is intended to discuss the practicalities of various use
    cases and to establish a consensus around the problem space and
    desirability of developing solutions in this area with a view to
    determining whether the IETF should have a Working Group on this topic.

  * Responsible Area Directors: Adrian Farrel and Stewart Bryant
  * BoF Chairs: Alvaro Retana, John Scudder
  *

  * Mailing list: https://www.ietf.org/mailman/listinfo/status

Further details can be found  at http://trac.tools.ietf.org/bof/trac/wiki

- Stewart

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From: Thomas Narten <[email-masked]>
Date: Thu, 20 Jun 2013 16:26:26 -0400

Hi Stewart.

One thing that might be worth clarifying up front.

Is there already a sense at this point whether the BOF is intended to
form a WG post-berlin? Or is this really exploratory, with an
assumption that a lot more work would need to be done with a followup
BOF in Vancouver for formal WG creation (assuming things work out, of
course)?

FWIW, I assume it's exploratory. In any case, clearly laying out
expectations would help level-set things.

Looking at the BOF wiki, there is no draft with a problem
statement. Reading the description, I don't quite understand if this
is "MPLS only" or whether it really is broader and impacts IP. There
is an explicit mention of IPv6 in the text (which caught my
attention), but I don't see right off what that means.

Are there additional drafts in the works that will clarify all this?

What's the thinking here?

Thanks!

Thomas

---

From: Stewart Bryant <[email-masked]>
Date: Fri, 21 Jun 2013 13:27:58 +0100

> BOF in Vancouver for formal WG creation (assuming things work out, of
Hi Thomas

That is one of the questions that we need to answer over the next
few weeks. The technique has had a quiet resurgence in a number
of companies over the past few years. One of the tasks of the BOF is
to determine whether this something that the IETF should work on
and if so, on what timescale we should consider a WG. I know that
you know the options, but for those that do not, we could emerge
in position where we think that there is more work to do and may have
a BOF in Vancouver or London to form a WG. On the other hand
we may leave the meeting in Berlin with the ADs effectively
instructed by the community to immediately work on getting
a charter approved. So I am looking for the views of the
community on exactly this question.

> statement.
Correct, although a number of companies have been working
on a use case draft in the background.
> Reading the description, I don't quite understand if this
> is "MPLS only" or whether it really is broader and impacts IP.
There is interest in (re)introducing a constrained form of source
routing to IP. Operators that run non-MPLS networks seem to
be interested in an IP approach. Others are questioning why we
need anything other than MPLS. So this is a matter that we need
to investigate. A well designed architecture and control plane
would be agnostic to the packet forwarding/encapsulation
approach.
> There
Yes, but there is currently no draft uploaded, although the
there has been recent discussion at conferences for both IPv6
source routing and of some interesting OAM approaches that
rely on a source routing approach. I hope that the advocates
of those technologies will be encouraged to write them up
in drafts.
> What's the thinking here?
I understand that there will be more drafts in the next week or so.

Stewart