RE: [EXTERNAL] Re: Extending a /64 (The most welcome comment)

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

Brian,

> How about an ops Area draft describing how the proposal works with BGP4 and how many new BGP routes it will create?

I am not well liked in ops, but if Tony is up for another document and has
enjoyed the IETF "ride" thus far sure why not. What do you think, Tony?

Fred

> -----Original Message-----
> From: Brian E Carpenter [mailto:[e-mail]]
> Sent: Wednesday, November 18, 2020 2:20 PM
> To: Templin (US), Fred L <[e-mail]>; Tony Whyman <[e-mail]>; [e-mail]
> Subject: [EXTERNAL] Re: Extending a /64 (The most welcome comment)
>
> Fred,
> 
> My concern isn't about what happens inside the ICAO limited domain. What you say makes complete sense there. It's about how
> these prefixes (fail to) aggregate in what we used to call the default-free zone. (RFC1888 probably would have had that problem too,
> but as far as I know, nobody ever implemented it.) If there was a bgpops WG, that would be the place to discuss it.
> 
> If the plan creates a new DFZ route for each airline, that's a negligible number in the BGP4 context. If it creates a new DFZ route for
> each aircraft, that could be problematic.
> 
> How about an ops Area draft describing how the proposal works with BGP4 and how many new BGP routes it will create?
> 
> Regards
>    Brian
> 
> On 19-Nov-20 10:27, Templin (US), Fred L wrote:
> > Brian, there will be many non-airplane users of the ATN/IPS top-level IPv6 prefix
> > allocation - often in fixed and non-mobile environments - and we can expect them
> > to conform to CIDR conventions. We are only talking here about the airplanes,
> > which are always mobile and always away from "home".
> >
> > I have shown how we can route their prefixes using scalable de-aggregation,
> > and you seemed to concur. So, why can't we tolerate a 24-bit portion of the
> > airplane's prefix that does not come from a strict CIDR hierarchy?
> >
> > Fred
> >
> >> -----Original Message-----
> >> From: ipv6 [mailto:[e-mail]] On Behalf Of Brian E Carpenter
> >> Sent: Wednesday, November 18, 2020 12:10 PM
> >> To: Tony Whyman <[e-mail]>; [e-mail]
> >> Subject: [EXTERNAL] Re: Extending a /64 (The most welcome comment)
> >>
> >> Tony,
> >>
> >> I don't like the argument that people are arguing for either "purity"
> >> or "perfection". That is not the issue. The issue is doing something
> >> that matches how IPv6 wide-area routing actually works, and that is
> >> by CIDRised prefix allocation.
> >>
> >> Now you have peeled back the onion to this point:
> >>
> >>> we have to have an addressing plan (for
> >>> aircraft) that is canonical with the existing NSAP Address.
> >>
> >> I understand that as a perceived requirement; it's more or less why
> >> we wrote RFC1888, although mapping US GOSIP addresses was the target
> >> then. I don't know how the ICAO lays out its NSAPA addresses, but I
> >> imagine that the aircraft ID is towards the low-order bits?
> >> That's where it should be in an IPv6 address, IMNSHO.
> >>
> >> The current proposal seems to be limited to 16 subnets on an
> >> aircraft and that is highly likely to come back and bite you.
> >>
> >> Regards
> >>    Brian Carpenter
> >>
> >> On 18-Nov-20 22:33, Tony Whyman wrote:
> >>> On 18/11/2020 03:30, Michael Richardson wrote:
> >>>> When we designed IPv6, we assumed that everyone would get some, even if they
> >>>> didn't connect.
> >>>>
> >>>>      > ULAs only have the first property.
> >>>>      > If a device doesn't need the second property, the device doesn't need a GUA.
> >>>>
> >>>> Again, what is this business of trying to ration IPv6?
> >>>> Do they really need 39 bits? I don't know.
> >>>>
> >>>> Our entire Ipv6 architecture ENCOURAGES entities to ask for the amount of space
> >>>> that they think they might need over the lifetime of their effort and NEVER
> >>>> COME BACK for more.
> >>>>
> >>>> That's why /64 for IIDs, and /48s for every site.
> >>>
> >>> If there is another edition of RFC 8200 then the sentence beginning "Our
> >>> entire.." should be copied to the front page of the new edition. Yes, we
> >>> all get the idea that addressing plans should be as elegant as possible
> >>> - but IPv4-think should have no place in this. But, perhaps the most
> >>> important notion that comes through in the above is that each industry
> >>> ultimately knows best when it comes to the compromises that have to be
> >>> made to create an industry specific addressing plan.
> >>>
> >>> Over the last few days, I have been happy to try and peel away the
> >>> issues that lay behind our proposed IPv6 addressing plan and to use it
> >>> as an opportunity to spread understanding of the ATN/IPS and the
> >>> constraints under which we are working. However, there is one point that
> >>> it seems to be too difficult for some to get their head around and that
> >>> is that we are not starting with a "clean sheet of paper". We have to
> >>> respect the constraints that we have and sometimes arguably poor
> >>> decisions that were made in the past and the result is a compromise. It
> >>> will offend those who demand purity - but purity is not the objective.
> >>> The objective is to deploy a working IPv6 based system.
> >>>
> >>> In the ICAO Working Groups, we are writing the 3rd edition of the
> >>> ATN/IPS Manual. There were two earlier versions and both represent
> >>> failed attempts to deliver an IPS based ATN. They failed - not
> >>> necessarily for technical reasons - but because there was no business
> >>> case. This is a very hard nosed industry and, unless its use is
> >>> commanded by regulation, if a new technology does not deliver more
> >>> passengers or raise the profit/passenger then it ain't going to happen.
> >>>
> >>> Even now, I am hard pressed to see any business case for an ATN/IPS
> >>> replacing the venerable ATN/OSI. The ATN/OSI is a CLNP overlay on top of
> >>> an IPv4 network, it works, with some limitations, and will support the
> >>> current generation of applications. With nugatory upgrades it could
> >>> support the next generation. Some might point to presumed cost savings
> >>> by replacing CLNP with something that is industry mainstream - but the
> >>> truth is that the CLNP bits are, by and large, in systems that perform
> >>> functions that are unique to civil aviation, while the rest is catalogue
> >>> item routers.
> >>>
> >>> However, looking to the long term, it will be increasingly difficult to
> >>> develop new applications on the ATN/OSI base and we should seize the
> >>> first opportunity that we can find to move on to an ATN/IPS.
> >>>
> >>> A funding window has opened up with the European Space Agency (ESA) and
> >>> the EU's SESAR research programme putting in the funds to develop a
> >>> prototype SATCOM service for the ATN/IPS. This should just about extend
> >>> to cover initial avionics on a single aircraft type (different
> >>> generations of aircraft have different communication architectures and
> >>> everything has to be type approved before it can be used). The funding
> >>> should also cover a protocol gateway allowing the prototype to interwork
> >>> with ATC Centres i.e. to at least demonstrate an operational service
> >>> using the ATN/IPS.
> >>>
> >>> Even stretching the funding envelope this far is optimistic. Adding in
> >>> anything else like a new registration scheme for aircraft and lookup
> >>> tables in the protocol gateway will kill the project financially. Yes, I
> >>> know that these are not technically difficult, but when you work in an
> >>> environment where every new function has to be subject to a hazard
> >>> analysis, a safety case, a high end develop lifecycle and rigorous
> >>> testing then, what looks like a simple function on paper, quickly gets
> >>> replaced by a dollar sign followed by lots of digits.
> >>>
> >>> To keep this project feasible, we have to have an addressing plan (for
> >>> aircraft) that is canonical with the existing NSAP Address. You may
> >>> prefer purity and demand that we have a perfect addressing plan. But you
> >>> are not helping.
> >>>
> >>> Our goal is to get a working ATN/IPS on to a single aircraft type with
> >>> minimum change to the existing system. Once this has been demonstrated
> >>> to be feasible and "industry mainstream" then the case can be made for
> >>> rolling it out to other aircraft types and, may be, one day, even the
> >>> ATC Centre's will get upgraded - but that will probably have wait until
> >>> a new application provides the business case.
> >>>
> >>> Perhaps another aphorism that could be put on the front page of a future
> >>> version of RFC 8200 is "never let the perfect be the enemy of the good".
> >>>
> >>> Regards
> >>>
> >>> Tony Whyman, MWA
> >>>
> >>> PS: we could always declare the ATN as a closed network and use our own
> >>> addressing plan - but does not help make the "industry mainstream" case,
> >>> does it.
> >>>
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