Subject: [spring] WG Adoption Call for draft-previdi-spring-problem-statement - Section 3

From: Yakov Rekhter <[email-masked]>
Date: Mon, 24 Mar 2014 10:42:41 -0700

Alvaro,

> Hi!
> 
> This message officially starts the call for adoption for
> draft-previdi-spring-problem-statement.
> 
> Please indicate your position about adopting this use cases draft
> by end-of-day on March 27, 2014.
> 
> Some additional background:  We had issued a call for adoption for
> draft-filsfils-rtgwg-segment-routing-use-cases-02 back in November.
> From both the discussion at the meeting in Vancouver and on the
> list, there was consensus to adopt.  The authors published
> draft-previdi-spring-problem-statement-00 as a revision to the
> original draft without the solution being present in the use case
> description.
> 
> http://tools.ietf.org/html/draft-previdi-spring-problem-statement
> 
> Thanks!

Section 3 of draft-previdi-spring-problem-statement presents IGP-based
MPLS tunnels as a use case for SPRING. Since SPRING is about
source/explicitly routed tunnels, then the use case of IGP-based
tunnels is outside the scope of SPRING.  After all, these IGP-based
tunnels are *not* source/explicitly routed.

Yakov.

---

From: Robert Raszuk <[email-masked]>
Date: Mon, 24 Mar 2014 20:37:16 +0100

Hi Yakov,

> After all, these IGP-based tunnels are *not* source/explicitly routed.

The definition of "source routing" states that source routing is the
ability which allows a sender of a packet to partially or completely
specify the route the packet takes through the network

Let's notice that it says nothing about the src of such information.
Such source of this information can be coming from various sources or
routing protocols including IGPs.

Charter says:

" Full explicit control (through loose or strict path specification)
can be achieved in a network  comprising only SPRING nodes, however
SPRING must inter-operate through loose routing in existing networks
and may find it advantageous to use loose routing for for other
network applications."

The above quite directly allows SPRING WG to work on "loose paths" and
"loose routing" therefor IGPs can be used just fine to propagate such
explicit control information.

Thx,
R.

On Mon, Mar 24, 2014 at 6:42 PM, Yakov Rekhter <[email-masked]> wrote:
> _______________________________________________
> spring mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/spring

---

From: "Stefano Previdi (sprevidi)" <[email-masked]>
Date: Wed, 26 Mar 2014 09:49:45 +0000

Hi Yakov,

thanks for the comment. See below.

> tunnels are *not* source/explicitly routed.

alternatively, one could consider the endpoint of the tunnel being 
an explicit request. This makes igp tunnels the simplest form of 
source route tunnels.

Anyway, this could end up into a rhetorical discussion... 

The idea behind section 3, is to illustrate that any source routing 
mechanism spring may standardize, MUST also be able to address the 
very simple form of routing in today's networks: egress point tunnels.

Thanks.
s.