Re: [Int-area] Some thoughts on draft-yong-intarea-inter-sites-over-tunnels

["Templin, Fred L" <[e-mail]>]

Hi Joe,

> -----Original Message-----
> From: Joe Touch [mailto:[e-mail]]
> Sent: Wednesday, November 30, 2016 2:32 PM
> To: Templin, Fred L <[e-mail]>; Lucy yong <[e-mail]>; Brian E Carpenter
> <[e-mail]>; [e-mail]
> Subject: Re: [Int-area] Some thoughts on draft-yong-intarea-inter-sites-over-tunnels
> 
> Hi, Fred (et al.),
> 
> 
> On 11/30/2016 12:51 PM, Templin, Fred L wrote:
> > Hi Joe,
> > ...
> > I didn't mention route optimization. With AERO, route optimization is what happens
> > when the tunnel ingress switches from an egress that is on a suboptimal path to a
> > different egress that is on a better path.
> That's internal to the tunnel itself, related to the fact that your
> tunnel is multipoint and treats all egresses as valid.
> 
> That's another feature, but again it's hard to see where that would be
> discussed. It's closest in spirit to egress determination in BGP or
> LISP, and has no clear relation (AFAICT) to INTAREA (expertise or
> purview). However...

It is the same as the way the Redirect function works on physical links, except
that the Redirect applies to an entire network prefix and not just a singleton
address. This has already been published in RFC6706, and what we are now
specifying is essentially RFC6706(bis).

> > Due to the link nature of the NBMA overlay,
> > that switching is accomplished through the use of IPv6 ND Redirect messages the
> > same as would occur on a physical link (and in the same spirit as published in RFC6706).
> I don't think I would call that routing either when it happens in a
> regular network or inside an NMBA tunnel.

It is the moral equivalent of the Redirect function on physical links.

> > That is why I ended up agreeing with you that fully embracing fragmentation is the
> > only way to truly handle tunnel MTU, because without fragmentation an MTU that
> > worked over the suboptimal path might fail over the new path once route
> > optimization is employed.
> >> And traffic engineering is easy
> >> in a tunnel *if* it's supported in the base network over which the
> >> tunnel operates, and impossible otherwise.
> > Traffic engineering as in allowing the Client to select both the outbound underlying
> > interface for outbound traffic and the inbound underlying interface for inbound
> > traffic.
> A tunnel ends at interfaces. Client determination of interfaces happens
> separate from a tunnel, IMO.
> 
> > So, a device that has both cellular and WiFi can send and receive packets
> > with different TOS markings over both interfaces simultaneously (e.g., TOS '1' goes
> > out over cellular, TOS '2' goes out over WiFI, etc.) and respectively for the
> > inbound direction.
> 
> That's the job of interface selection in the host, which is already
> specified in RFC1122 and extensions. Are you suggesting a change to
> that? If so, it seems like it's completely orthogonal to the use of
> tunnels as interfaces.

The AERO interface is an NBMA interface where the ingress sees all potential
egresses as potential "neighbors". An AERO interface that is configured over
multiple underlying interfaces would appear to have multiple link-layer
addresses. Each link-layer address can have a different set of TOS-based
priorities so that the AERO interface can specify to its neighbors as to
which link-layer address to use for which class of traffic.

>From an IPv6 neighbor discovery standpoint, this is realized by allowing IPv6 ND
messages to include multiple S/TLLAOs - one for each underlying interface. Each
S/TLLAO has a set of TOS-based priorities allowing neighbors to select the best
underlying interface for the given packet TOS. This is described in Section 3.5
of the document. I can demonstrate how this works in actual running code
over a webex if you would like.

> >> I'm not claiming this wouldn't be useful.  I'm saying that we need to
> >> know what problem it solves to know where to home it.
> > I have identified two very important use cases relating to aviation.
> You've defined a customer, IMO - which is great, but short of taking
> this to an aerospace forum, it doesn't really help me understand where
> in the IETF it should be discussed.

It is being proposed to the International Civil Aviation Organization (ICAO)
where standards are being established for the future civil aviation data
communications architecture.

Thanks - Fred
[e-mail]

> > So, the fortuitous
> > selection of the AERO acronym now seems quite appropriate. We are also using it for
> > mobile VPN management for corporate enterprise mobile device users (cellphones
> > and tablets), and we are planning to release source code soon.
> 
> That's all good news, but I'm still left not quite understanding where
> in the IETF this should (or could) be handled. We don't really have a WG
> for creating tunnels and I'm not sure INTAREA should serve as  a default.
> 
> Joe