[ppml] Policy Proposal 2005-1: Provider-independent IPv6

[Peter Sherbin]

> I do not believe that any routing solution based on using the same number for end
> system identifier (ID) and topological locator (LOC) can scale. 

Agree. IPv6 address is long enough to break ID/LOC link allowing routing solution to
be based e.g. on LOC only and leaving ID function to a complete customer discretion
as an imbedded purpose.

Peter

--- Owen DeLong <owen at delong.com> wrote:

> I promise, last post for a while on this topic.
> 
> 
> --On April 27, 2006 1:10:51 AM -0400 "Jason Schiller (schiller at uu.net)" 
> <jason.schiller at mci.com> wrote:
> 
> > I am against this policy.
> >
> > It seems that people really want multi-homing badly to make IPv6 work.
> >
> > Heidi Hinden's first law: When you want it bad, you get it bad, and most
> > people want it in the worst way.
> >
> Notwithstanding the fact that I have no idea who Heidi Hinden is or
> why I should obey her laws... I don't think that's an accurate analysis
> of the situation at all.
> 
> I think that there is a large(ish) portion of the network community
> which does not remember the pre-CIDR internet and does not remember
> or realize that the limitations imposed by CIDR were once viewed as
> a very bad thing which broke a lot of functionality. There are a
> small number of people who do remember the pre-CIDR internet.
> 
> Interestingly, both of these groups are subdivided into two groups...
> 
> In those who do not remember the pre-CIDR internet, we have group A,
> mostly comprised of large(ish) ISPs who like the customer-lock-in
> aspects of CIDR and don't want to let go of that marketing leverage.
> These are the ones which also want to use reductio ad absurdum
> arguments about the size of the mythical global routing table and
> address the fact that once upon a time, the BGP table exceeded the
> capabilities of the AGS+ routers available at the time.
> 
> On the other hand, we have group B, who don't remember pre-CIDR,
> but, they want their PI space like they have in v4, and, they want
> to be able to multi-home, and, they don't want some overly-complex
> solution that requires support on far-end hosts they have no way
> to influence or control.
> 
> Now, in the case of those that remember, we also have two groups.
> Group C, much like group A, is largely comprised of people from
> large(ish) ISPs who espouse largely the same position.  In fact,
> any distinction between group A and group C is purely an academic
> exercise as near as I can tell.
> 
> On the other side of those who remember, we have group D. This
> group is not ignorant of the limitations of the routing system.
> We are not (yes, I consider myself a member of group D) unaware
> of the issues with routing table growth in the current architecture.
> However, we also remember that one of the primary goals for the
> development of v6 was to FIX THIS.  So far, it hasn't been fixed.
> Between v4 and v6, really, nothing changed in terms of routing.
> 
> However, for both v4 and v6, I am convinced that these issues
> are far less urgent today, although I agree the problem has not
> been completely solved.  Fortunately, I think the problem _CAN_
> be solved and that we have approximately 10 years to solve it.
> 
> Here's how I figure it:
> 
> 1.	The current routing table is comprised of just over 20,000
> 	active ASNs. The current v4 Prefix:ASN ratio is close to 8:1
> 	on average, with the peaks advertisers being several hundred
> 	and the lows being 1. In the v6 world, this number should be
> 	much much closer to 1:1, probably somewhere around 2:1 will
> 	be realistic. That means that the current routing table
> 	translated to a v6 world will shrink to less than 50,000 routes.
> 	That should give us lots of headroom for v6 growth as v4
> 	becomes less and less prevalant and eventually is not
> 	globally routed.
> 
> 2.	It is unlikely that the internet will see anywhere near the
> 	explosive growth of the 90s in the next 5-10 years. Even if it
> 	did, we would still stay well short of 160,000 v6 routes which
> 	is well under most estimates I've heard for current hardware
> 	capability.  As such, there shouldn't be much of a problem
> 	for at least 10 years.
> 
> 3.	The large(ish) ISPs comprise the majority of the operational
> 	focus in the IETF, and, indeed have been a strong enough force
> 	there that they were able to get RFCs cranked out which
> 	attempted to preserve a completely provider-dependent
> 	addressing model for the v6 internet.  As such, faced with
> 	building a scalable routing system or waiting for the network
> 	to implode, I would hope that they will start working towards
> 	a more scalable solution, such as ID/LOC splits.
> 
> 4.	I think that if IETF and large(ish) ISPs and router vendors
> 	work towards a solution, 10 years is more than enough time for
> 	development, testing, and, early deployment.
> 
> 5.	Vendor focus, in my experience, tends to be towards making
> 	the large(ish) ISPs happy and the majority of enterprises
> 	are a secondary consideration.  This makes sense when you
> 	consider that the average large(ish) ISP spends several
> 	million dollars per year with their router vendor(s) of
> 	choice, while the rest of the world is significantly less
> 	per enterprise (in most cases) spread over a much wider
> 	collection of sales representatives.  In most sales-oriented
> 	organizations (which as near as I can tell, all the hardware
> 	vendors are today), the sales rep with the largest dollar
> 	value tends to have the largest say in the feature priorities.
> 
> 
> > What concerns me are three things:
> >
> > 1. Enterprise customer who want PI addresses or useful multi-homing, and
> > don't care about the problems it creates for the large ISPs that carry
> > full routes.  (That's their problem.)
> >
> > In reality it is everyone's problem
> > if they want to transit one of these ISPs, or use best path routing
> > (carry full routes and not just a default to a transit provider).
> >
> > Lets not forget that router vendors are behind the curve on port speeds
> > too.  Are these vendors more likely to solve the routing table problem
> > that affects only the largest ISPs or focus on port speed problems that
> > affect many large enterprise customers?
> >
> Yes, in today's architecture, if we assume that this policy will double
> the number of ASNs and that the advertising ratio for v6 does come out
> close to 2:1, we'll see a v6 routing table, fully deployed, of about
> 100,000 routes.  That's still smaller than the current v4 table, and,
> that's assuming that the number of ASNs issued doubles (which I think is
> unlikely in the next 10 years).
> 
> > 2. The concern people are being short sited and since there are only 1,000
> > routes in the IPv6 Internet table that this will not be a problem any time
> > soon.
> >
> No... People supporting this policy aren't looking at 1,000 v6 routes and
> saying "see... v6 table has lots of room".  They're saying "Look: v6 is
> failing to gain acceptance.  Further, looking at the number of ASNs in
> v4, we can extrapolate that v6 will have better aggregation per ASN, and,
> thus we shouldn't see more than 2:1 prefix ratio in v6. That means that
> the current v4 internet could be re-implemented in v6 with less than 50,000
> routes (vs. the current 180,000+)."  I don't mind that you disagree with
> our argument, but, please don't call us short-sighted or ignorant
> using a different argument than the one we presented.
> 
> > 3. The concern that we haven't done enough research to know if the vendors
> > will be able to stay far enough ahead of the route table growth to not
> > have a problem.  It is not enough for vendors to build the routers big
> > enough in time.  If it takes 3 years to fully replace a network, and the
> > router vendors are only two years ahead of the curve, then I only get 2/3
> > through my upgrades before having to start a new set of upgrades.  Never
> > mind being able to depreciate the cost of the router over 5 years.
> >
> I think it doesn't matter.  ISPs will route what ISPs will route.  Having
> ARIN addressing policy protect ISPs from the legitimate demands of their
> customers is an inappropriate use of policy in my opinion. ARIN should
> neither encourage nor prohibit the routing of any prefix by any ISP.
> That should be a contractual matter between the ISPs and their peers
> and customers.
> 
> Having said that, I also think that the only real way to address the
> true needs of the community is by coming up with a scalable routing
> solution. I do not believe that any routing solution based on using
> the same number for end system identifier (ID) and topological
> locator (LOC) can scale.  I do think that there are possible advantages
> to having some level of geographic distribution of these PI addresses
> and I encourage the research and effort that is being done toward
> that end at this time.  However, I hope that IETF will see this
> policy (and similar discussions starting to happen in other RIRs)
> and start working on a viable long-term routing protocol so that we
> can deploy it before this really becomes an issue.
> 
> > We have to understand what it means to make a long term commitment to
> > deaggregation.  I don't hear the six largest ISPs standing up and saying
> > we did some studies of what the routing table will look like in five to
> > ten years, and have talked to our vendors and we don't think it will be a
> > problem.
> >
> You're right.  Instead, you hear a reasonable sampling of their customers
> standing up and saying "We're not going to take this any more" about the
> provider-lock-in based addressing of the CIDR world.
> 
> 
> > The point Aaron was trying to make was in reference to my
> > projections.  For example I want to buy new routers today.  It takes 2
> > years to certify and fully deploy the router throughout the network.  I
> > want the router to live in the network for 5 years to depreciate the
> > value.  That means if by 2011 there is wide spread adoption of IPv6 the
> > router will need to support 1.3M routes.  This example does not take into
> > consideration L3VPN routes, or routes from converging multiple networks
> > onto a single chassis.
> >
> Where on earth did you get the idea that there would be 650,000 active
> ASNs by 2011?  You're going to have to work real hard to show me
> any reasonable projection that predicts such a value.
> 
> If you're claiming that would be the sum of v4 and v6 routes, I would
> argue that if v6 adoption is that wide by 2011, the majority of the
> core would be v6 and v4 routes would become native only in local pockets.
> Across the core, they would be v4 in v6 tunnels, so, the big 6 would
> have alternatives to carrying both sets of routes in any one router.
> Also if v6 adoption is that widespread, I think that the number of people
> still using v4 would be significantly reduced if, for no other reason,
> ISPs will start charging extra to preserve v4 infrastructure by then.
> 
> Bottom line, I think your projections are simply unrealistic by any
> 
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