Re: [External] Request for information - Challenges in routing related to semantic addressing

Hi Adrian,

My main comment to the draft is that the center of gravity is placed on
addressing semantics without clearly started if this draft is talking about
flat global addressing or local encapsulation. Sort of reader assumes it is
applicable to both.

Both tunnels and encapsulation words occur 3 times each in the entire
document.

It may be perhaps better to restructure it such that for global routing
system semantics of given address is different while in my network I can
use it to encapsulate and switch packets with much more freedom.

Kind regards,
Robert.

On Mon, Feb 15, 2021 at 7:01 PM Adrian Farrel <adrian@olddog.co.uk> wrote:

> Thanks Tony, Joel, et al.
>
>
>
> It is, perhaps not surprising that the discussion gravitates to “what is
> semantic addressing” and “what problems is it trying to solve”. And given
> that way of reading the draft, I suppose I am not surprised by being
> “accused” of suggesting that that semantic addressing is a solution for
> specific problems.
>
>
>
> In fact (maybe the draft isn’t clear enough, maybe my mail to this list
> wasn’t clear enough), what we are trying to do is establish what research
> has been done on the implications for the routing system of what Tony calls
> “overloaded addresses”, and to set out the research questions that we think
> need to be looked into.
>
>
>
> Along the way, and to give context, I think it is important to list out
> the proposals for adding semantics to addresses, and I think it is
> necessary to give a high-level accounting of what problems people think
> they are solving. But, as I said in my original email,
>
> > This document is deliberately NOT discussing:
>
> > -          Are these address semantic schemes wise or crazy?
>
> > -          Is it legal to place semantics in addresses?
>
> > -          Is it even possible to achieve overloading of addresses?
>
> > What we are doing is zooming in on any existing research of the impact
>
> > on the routing system and, absent that, to list out the questions that
>
> > should be answered by research.
>
>
>
> It seems to me that it is quite likely that many people have strong
> opinions about things that might go wrong. It also seems to me that a
> really good way to prove whether something is good or bad is to do the
> research. That’s what we’re looking for.
>
>
>
> Keep discussing 😊
>
>
>
> Adrian
>
>
>
>
>
> *From:* Tony Li <tony1athome@gmail.com> *On Behalf Of *Tony Li
> *Sent:* 15 February 2021 17:44
> *To:* Joel M. Halpern <jmh@joelhalpern.com>
> *Cc:* King, Daniel <d.king@lancaster.ac.uk>; Adrian Farrel <
> adrian@olddog.co.uk>; draft-king-irtf-challenges-in-routing@ietf.org;
> routing-discussion@ietf.org
> *Subject:* Re: [External] Request for information - Challenges in routing
> related to semantic addressing
>
>
>
>
>
>
>
> On Feb 15, 2021, at 8:10 AM, Joel M. Halpern <jmh@joelhalpern.com> wrote:
>
>
>
> I can't argue with an effort to define the term "semantic routing".
> However, I would be very concerned by an effort to define goals for it
> before we have such a definition.  Depending upon the definition, the
> answer may be that it is a bad idea.
>
>
>
>
>
>
>
> I’ll go a bit farther.
>
>
>
> In reading this draft, I’m struck by the lack of clear articulation of
> some of the fundamentals of the architecture. Routing and addressing are
> functionally tied together and
>
> any discussions of modifications to one requires a clear discussion of how
> it would affect the other function. We learned long ago that overloading
> functionality on packet fields is a poor design choice,
>
> and even the early decision to overload identification onto location has
> had profound and deleterious effects that we have still not overcome.  In
> fact, you list the impacts of this architectural error
>
> as things that you’d like to fix: multihoming, mobility, and multipath
> routing.
>
>
>
> It’s also somewhat concerning when you list Scalability as one of the
> goals that you are proposing to fix with semantic overloading. It should be
> clear that any overloading of the address space
>
> will reduce, not improve, its flexibility and thereby limit, not enhance
> Scalability.
>
>
>
> If and when there is a clear definition of “semantic routing” and a clear
> proposal on how to move forward, there must also be a clear discussion of
> the affects of overloading addressing will
>
> affect routing.
>
>
>
> The original purpose of giving IPv6 128 bits of address space was to
> ensure that there was continued scalability for the routing system for the
> next 20 years (which have now expired ;-). In fact,
>
> what we’ve learned is that transitioning to a new network layer takes a
> lot longer than what we had hoped and that the lifetime of a network layer
> is far more than expected. Thus, we should
>
> be aiming to preserve IPv6 functionality in perpetuity and not simply for
> the next generation. To this end, we must be very careful about any
> unintended side-effects from overloading addressing,
>
> especially with regards to routing scalability.
>
>
>
> We have a fine example of this when we decided that most end sites would
> be granted a /64 prefix. This effectively took half of the addressing bits
> off of the table for global routing and since addressing is
>
> hierarchical, this was a logarithmic decrease in overall routing
> scalability. Meanwhile, most of the individual sites are domestic networks
> that will never ever subnet.
>
>
>
> So, please be very clear about the impacts of any proposal that suggests
> overloading addressing. The impact to the architecture will definitely be
> non-trivial and thus it bears careful consideration.
>
>
>
> Regards,
>
> Tony
>
>
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