On 7/16/14, 2:55 PM, Linda Dunbar wrote:
Agree with Dino.
Why can't the extra information being carried by the NSH shim?
Right. That's what we're suggesting with GPE: use a shim header, a-la
NSH, to carry extra metadata and keep the basic structure of the VXLAN
(and LISP, to a lesser extent) header the same.
Fabio
Linda
-----Original Message-----
From: nvo3 [mailto:[email protected]] On Behalf Of Dino Farinacci
Sent: Wednesday, July 16, 2014 3:05 PM
To: Fabio Maino
Cc: [email protected]
Subject: Re: [nvo3] Comments on
http://tools.ietf.org/html/draft-quinn-vxlan-gpe-03
Well, if you want to really care about customers, creating all these variations
is not doing justice to them. If you want less combinations, you keep VXLAN the
way it is right now, with no changes. You keep LISP the way it is right now
with no changes. You get L2 and L3 overlays with a unified pull control-plane
in draft-maino-nv03-lisp-cp (preaching to the author ;-) or use BGP as an
alternative push control-plane.
As for NSH, you create a new header because it is completely new requirement
and has not be deployed anywhere. Since it is brand new, you need new hardware
and code to be developed to support it. So changing VXLAN and LISP to support
NSH doesn't make sense because you inject change in 3 places rather than in 1
new place, creating more protocol machinery, complexity, and combinations that
will frustrate customers (not to mention vendor call centers).
Less entropy please,
Dino
On Jul 15, 2014, at 10:51 PM, Fabio Maino <[email protected]> wrote:
Dino,
I believe that using a format that can share as much as possible with the two
protocols deployed today will give a better chance to GPE to be implemented, as
vendors may want a cost effective way to migrate to the new protocol while
preserving compatibility with legacy implementations.
The fact that GPE provides a way to be extended, either with a shim a-la NSH or
making availabe more bits in the header for future features, I think opens up
to the addition of new features (explicit service tagging, as an example) in a
more organic way than trying to use the few bits left in VXLAN or LISP.
Unfortunately, in the LISP case, this comes to the expense of some features
that are in the current specification, but I believe those same features can be
mapped on a GPE+shim header, so a new implementation would be able to provide
the equivalent of those features (e.g. nonce).
It's hard to find the right balance between backward compatibility and
evolution of the encapsulation, but I believe GPE gets to a decent compromise.
Thanks,
Fabio
On 7/15/14, 4:47 PM, Dino Farinacci wrote:
Hi VXLAN-gpe authors,
Abstract: technically this is not extending a VXLAN but defines a
new protocol that looks similar to VXLAN (demonstrated by need for
new UDP port assignment).
We are trying to balance re-use of the VXLAN format and the need to support
existing non-GPE hardware that might already be deployed. We looked at using
the same port, and the new one, and decided, at this point that a new port is
easier for migration but since the packet format is essentially VXLAN to keep
the VXLAN name.
Paul, this design seems to be going in circles. If a new port is used, why not
make the new port for VXLAN mean layer-3 protocols follow? Or better yet, have
a demux field after the VXLAN header so you don't have to use VXLAN header
bits. Because the P-bit is using a precious bit in the VXLAN/LISP header and
the nonce field that can be used for other things (we have history that shows a
nonce in the header is a cheap form of obscure security).
If you do this then you have no compatibility problems with initial VXLAN and
LISP implementations.
And, most importantly, there will be less confusion in the marketplace.
Dino
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