Re: a radical proposal (Re: protocols that don't meet the need...)
[[pushed the wrong button last time. This is the complete reply]]
- join a local IXP, which may be a physical switch or virtualized by a set of bilateral agreements.
Why should they join an IXP if they already have private peering arrangements?
- outside the region, they advertise the prefix of the regional authority
Mixing government with operations? If you favor doing that then why not just give IPv6 addresses to the various national governments and let the UN sort it out? Personally I disagree with any scheme which calls for national or municipal governments to assign IPv6 addresses to end users. Dressing it up as a "regional authority" does not make it any nicer. Forcing people to join an unecessary IX is not the way to solve the problem of regional aggregation of routes. This is a purely technical problem which can be solved by the RIR practices in allocating IPv6 addresses. If they would allocate addresses in a geo-topological manner then end users and ISPs would be free to aggregate routes outside of their region without any involvement of governments or any requirement to join consortia or IXes. It does require the users of such geo-topological addresses to ensure that in THEIR region, there is sufficient interconnectivity (physical and policy) between ISPs for the addressing to work. But that does not need to be determined or managed centrally. Geo-topological addressing refers to RIRs reserving large blocks of designated addresses for areas served my large cities (over 100,000) population. When end users are located in fringe areas roughly equidistant between two or more such centers, the RIR simply asks the end user (or ISP) which is the center to which they want to connect (communicate). This addressing scheme operates in parallel with the existing provider-oriented IPv6 addressing scheme but uses a different block of IPv6 addresses out of the 7/8ths that are currently reserved. No hardware or software changes are required for this to work, merely some geographical/economical research to determine the relative sizes of the address pool to be reserved for each of the world's 5000 largest cities.
Whenever I have talked about the model with an ISP, I have gotten blasted. Basically, I have been told that
(1) any idea on operations proposed in the IETF is a bad idea because the IETF doesn't listen to operators
This is true. Top-down does not work in Internet operations. We need bottom-up, i.e. customer demand. The IETF needs to view their role as enablers of customer demand. If the IETF can create something that will work for ISP customers, then ISPs will be happy to go along, once the customers demand the service.
(2) the ISPs aren't going to be willing to make settlement payments among themselves in accordance with the plan
Wait until this starts appearing as a requirement in custome RFPs.
I'm not sure how to proceed, given the level of invective I get in any discussion with anyone on the topic.
Perhaps the IETF needs to seek input, not just from ISPs, but also from ISP customers, the end users of the network.
Note 2: Provider-provisioned addresses continue to make sense for folks that don't plan to multihome.
Indeed they do. But the current IPv6 addressing model is completely slanted towards provider-provisioned addresses for single-homed entities. Calling a small block of these provider-provisioned addresses PI (provider independent) does not really make the addresses provider independent and does not help small enterprises to implement meaningful multihoming. The IETF has imposed this provider-provisioned model on IPv4 and is thus directly responsible for the ISP cartel which now exists. --Michael Dillon
Uh-oh, two postings to NANOG in as many days... hopefully, this will be my last.
[[pushed the wrong button last time. This is the complete reply]]
Oh, the irony in that statement... this whole argument has certainly pushed "the wrong button" for me.
- join a local IXP, which may be a physical switch or virtualized by a set of bilateral agreements.
Why should they join an IXP if they already have private peering arrangements?
- outside the region, they advertise the prefix of the regional authority
Mixing government with operations? If you favor doing that then why not just give IPv6 addresses to the various national governments and let the UN sort it out?
Personally I disagree with any scheme which calls for national or municipal governments to assign IPv6 addresses to end users. Dressing it up as a "regional authority" does not make it any nicer.
Forcing people to join an unecessary IX is not the way to solve the problem of regional aggregation of routes. This is a purely technical problem which can be solved by the RIR practices in allocating IPv6 addresses. If they would allocate addresses in a geo-topological manner then end users and ISPs would be free to aggregate routes outside of their region without any involvement of governments or any requirement to join consortia or IXes. It does require the users of such geo-topological addresses to ensure that in THEIR region, there is sufficient interconnectivity (physical and policy) between ISPs for the addressing to work. But that does not need to be determined or managed centrally.
Geo-topological addressing refers to RIRs reserving large blocks of designated addresses for areas served my large cities (over 100,000) population. When end users are located in fringe areas roughly equidistant between two or more such centers, the RIR simply asks the end user (or ISP) which is the center to which they want to connect (communicate). This addressing scheme operates in parallel with the existing provider-oriented IPv6 addressing scheme but uses a different block of IPv6 addresses out of the 7/8ths that are currently reserved. No hardware or software changes are required for this to work, merely some geographical/economical research to determine the relative sizes of the address pool to be reserved for each of the world's 5000 largest cities.
The routing system doesn't particularly care whether your "geo-topo" addressing is imposed by governments, RIRs, or a beneveolent dictator; in all cases, the result is Soviet-style central planning to force the network topology to conform to your idea of what it "should" be rather than following the economic realities of the those who would build the network. A "geo-topo" addressing scheme works great for address assignment *within* a single AS and it even could have worked pretty well back in 1990, when there was a "core" NSFNET and a bunch of regional networks. But the key attribute of these scanerios is the existance of centralized control of the topology. There is no such control of the topology today; those who wish to impose such control are asking for a regulatory environment that would radically change the nature of the Internet.
Whenever I have talked about the model with an ISP, I have gotten blasted. Basically, I have been told that
(1) any idea on operations proposed in the IETF is a bad idea because the IETF doesn't listen to operators
This is true. Top-down does not work in Internet operations. We need bottom-up, i.e. customer demand. The IETF needs to view their role as enablers of customer demand. If the IETF can create something that will work for ISP customers, then ISPs will be happy to go along, once the customers demand the service.
Interesting to see an argument for bottom-up design in a post which otherwise calls for top-down planning of the network architecture. What the IETF, and more specifically the IAB, really needs to do is to acknowledge that there is a very real problem with the ipv6 routing architecture (which is identical to the IPv4 routing architecture), one that cannot be fixed without making incompatible changes to protocol implementation. Band-aids like shim6 just aren't going to cut it if the goal is to build a highly-scalable network of autonomous routing domains (in other worse, a really big network where end sites have very flexible choices of providers). The first step to finding a solution is to admit that there is a problem.
(2) the ISPs aren't going to be willing to make settlement payments among themselves in accordance with the plan
Wait until this starts appearing as a requirement in custome RFPs.
Then wait until governmental bodies step in to offer their help in the form of regulation. The two go hand-in-hand. If you want to re-invent the telco model of interconnection, this is a pretty big step in that direction. ...
Note 2: Provider-provisioned addresses continue to make sense for folks that don't plan to multihome.
Indeed they do. But the current IPv6 addressing model is completely slanted towards provider-provisioned addresses for single-homed entities. Calling a small block of these provider-provisioned addresses PI (provider independent) does not really make the addresses provider independent and does not help small enterprises to implement meaningful multihoming. The IETF has imposed this provider-provisioned model on IPv4 and is thus directly responsible for the ISP cartel which now exists.
Methinks we are re-interpreting history here. The IETF didn't create an "ISP cartel" for IPv4. What CIDR did, and I think I can speak with some degree of authority on this subject, was to allow routing state to scale in a non-exponential manner by encouraging address assignment to follow topology. Of course, the fact is that it is the providers which determine network topology because it is they who create it (this is something of a tautology). There are consequences of this, namely that provider changes imply renumbering, but this really isn't some grand scheme to lock customers in to providers; it is an unfortunate consequence of the combination of addressing following topology and a poor, late-1960's design decision to combine endpoint identification and routing locator into a single quantity known as an IP address. It is important to note that CIDR was explicitly specified as a short-term measure to prevent the explosion of routing state from causing the Internet to become unmanageable, which was the alternative to its adoption back in the early-to-mid-1990s. It was also explicitly intended to be replaced by a scalable, long-term solution which, unfortunately, has yet to be designed. If you don't believe me, go read the documents for yourself - they say exactly the same thing. In the interests of demonstrating why "geo-topo" addressing can't possibly work without radical changes to the business and regulatory models of the Internet, consider the simple example of a provider who has connections to two popular "geo-topo" addressing domains, say the Bay Area and the DC area. Let's say that 10.0.0.0/8 is the "geo-topo" address block in the Bay Area and 172.16.0.0/12 is the "geo-topo" block in the DC area. This provider has four customers in the Bay Area: 10.1.1.0/24 10.10.4.0/22 10.100.8.0/21 10.200.0.0/16 How is the provider supposed to make use of the 10.0.0.0/8 aggregate? Does he advertise it to other providers in the DC area or anywhere else where he offers service (Asia, Europe, etc.)? By doing so, he is stating that he can provide connectivity to all hosts which are numbered in that address range. But he only provides transit service to the address ranges associated with his customers. For him to provide connectivity to all the address range, he must a) have full routing connectivity to all other providers that have addresses in the same range; this implies that he connects to all IXs within the region and maintaines a full-mesh of routing information (today, BGP sessions) to all of these providers and b) must be willing to provide connectivity to all sites within the region to any place that he advertises the prefix 10.0.0.0/8 through routing exchanges; if he advertises this prefix to non-customers, it implies that he is will provide free transit to his competitors' customers which are numbered out of this block Both of these requirements defy business sense, so absent the imposition of strong regulation and negotiated settlements, they are unlikely to appeal to any provider which wishes to offer service to and between multiple cities; without such providers, you don't have a global Internet. I'm not sure how I can make this much more clear. It seems appropriate to re-state Dave's quote Yakov: "Addressing can follow topology or topology can follow addressing. Choose one." and I'd offer a corollary: Transit relationships (i.e money) must follow topological relationships (and thus addressing); the alternative is some combination of inefficient or non-scalable routing, black holes, settlements, regulation, or other undesireable things. If you really want to combine transport identifier and routing locator into a single "address", you give up a lot of flexibility. For routing to scale, addressing must follow topology, so in such a network architecture the term "topology independent address" (aka "provider independent address") is truly an oxymoron. --Vince
On Thu, 16 Feb 2006, Vince Fuller wrote:
to two popular "geo-topo" addressing domains, say the Bay Area and the DC area. Let's say that 10.0.0.0/8 is the "geo-topo" address block in the Bay Area and 172.16.0.0/12 is the "geo-topo" block in the DC area. This provider has four customers in the Bay Area:
10.1.1.0/24 10.10.4.0/22 10.100.8.0/21 10.200.0.0/16
customers. For him to provide connectivity to all the address range, he must
a) have full routing connectivity to all other providers that have addresses in the same range; this implies that he connects to all IXs within the region and maintaines a full-mesh of routing information (today, BGP sessions) to all of these providers
That's not quite correct. They would have to: a) Have full routing connectivity to all other providers who provide transit in/out of the area concerned. It does not imply: - having to peer with every provider in the area (some providers may be wholly within the area, you wouldn't need to peer with them, only their 'transit provider') - having to peer at every IX (you only need to fulfill condition a) - that peering with the other providers who provide inter-geo-area service, with whom you must peer as per a, must occur locally - it does not. (e.g. you could hand-off ACME providers Bay Area prefixes to ACME at DC if you want).
b) must be willing to provide connectivity to all sites within the region to any place that he advertises the prefix 10.0.0.0/8
Right.
through routing exchanges; if he advertises this prefix to non-customers, it implies that he is will provide free transit to his competitors' customers which are numbered out of this block
That's not correct. Nothing says it has to be free. If you're handing off X GiB of 10/8 Bay Area traffic to ACME provider each day, then you would (presumably) charge ACME your costs for those X GiB. ACME presumably would do likewise for traffic to 10/8 they carried that happened to be one of your customers instead. So it's normal peering business; indeed it could be a beneficial business model to try carry as much of that 10/8 traffic as possible. Some upsides: - scenic routing would be far less prevalent. - trivial provider-changing for customers / much increased competition (easier to attract new customers away from other providers). Some big downsides: - trivial provider-changing for customers (your competitors can get your customers to change over more easily than today) (I suspect providers would be more wary of this than they would welcome the /increase/ in competition ;) ). - every customer's (using these geo-assigned addresses) traffic is dependent on every transit provider. So ACMEs' customer could face an outage because "Barr's Internet Services" has a failure. This could be mitigated with good practices (ensure that those providers who provide transit into the area only ever originate the area-prefix from within the area, never outside - hard to know how that could be enforced) - Co-ordination of origination the prefix: How do you ensure that those providers who announce the 10/8 prefix are only those providers who are peered with all the others? Squabbles could get really ugly and affect /all/ users in that block, regardless of whether they are customers of the squabbling providers.
"Addressing can follow topology or topology can follow addressing. Choose one."
and I'd offer a corollary:
Transit relationships (i.e money) must follow topological relationships (and thus addressing); the alternative is some combination of inefficient or non-scalable routing, black holes, settlements, regulation, or other undesireable things.
We have settlements today already. The money factor isn't a problem really - seems to me at least the money aspect could work fine for geo-addressing, as it (should) do for transit services today. It's the other inter-provider co-ordination problems that would make it problematic. There'd need be someone who could "enforce the law", after defining the "law" of course ;). Though, we happen to have such a body in my country funnily enough.
If you really want to combine transport identifier and routing locator into a single "address", you give up a lot of flexibility. For routing to scale, addressing must follow topology, so in such a network architecture the term "topology independent address" (aka "provider independent address") is truly an oxymoron.
Right. The logical step then is for leaf-sites to build upon this topology-addressed network and advertise the lists of "topology identifiers" by which they are reachable to each other: shim6. Smart hosts communicating over a dumb network. Providers aren't happy with that either though, judging by some of the grumbling wrt shim6. But that's the only solution left unless some new 'break-through' solution is discovered. regards, -- Paul Jakma paul@clubi.ie paul@jakma.org Key ID: 64A2FF6A Fortune: Gold's Law: If the shoe fits, it's ugly.
Geo-topological addressing refers to RIRs reserving large blocks of designated addresses for areas served my large cities (over 100,000) population. When end users are located in fringe areas roughly equidistant between two or more such centers, the RIR simply asks the end user (or ISP) which is the center to which they want to connect (communicate). This addressing scheme operates in parallel with the existing provider-oriented IPv6 addressing scheme but uses a different block of IPv6 addresses out of the 7/8ths that are currently reserved. No hardware or software changes are required for this to work, merely some geographical/economical research to determine the relative sizes of the address pool to be reserved for each of the world's 5000 largest cities.
The routing system doesn't particularly care whether your "geo-topo" addressing is imposed by governments, RIRs, or a beneveolent dictator; in all cases, the result is Soviet-style central planning to force the network topology to conform to your idea of what it "should" be rather than following the economic realities of the those who would build the network.
Which part of "CHOICE" do you fail to understand? How does adding another choice get equated to Soviet central planning? In my opinion, central planning is what we have now. The IETF has imposed the provider-centric addressing model on us without asking whether we want that or not. Since only 1/8th of the IPv6 address space used this provider-centric model, there is plenty of room to offer an optional, geo-topological addressing model. Geo-top addressing is not about imposing a topology. It simply recognizes that the network largely follows the physical geography of cities linked by roads, and railways. It allows everyone to receive the benefit of the "nuclear survivability" inherent in IP by multihoming in their home city.
Interesting to see an argument for bottom-up design in a post which otherwise calls for top-down planning of the network architecture.
That should have been a hint that you totally misunderstood what I was proposing.
Methinks we are re-interpreting history here. The IETF didn't create an "ISP cartel" for IPv4. What CIDR did, and I think I can speak with some degree of authority on this subject, was to allow routing state to scale in a non-exponential manner by encouraging address assignment to follow topology.
In the interests of demonstrating why "geo-topo" addressing can't
work without radical changes to the business and regulatory models of
This isn't about CIDR. This is about the idea that there is a hierarchy of addressing with the ISP at the top, and the end user as a serf of their ISP overlord. That model was indeed imposed by the IETF, probably because at the time they were mostly working with benevolent overlords, i.e. universities. I want to see an alternative hierarchy so that end users are not tied to one overlord/ISP. possibly the
Internet, consider the simple example of a provider who has connections
Your example proves my point. There is no one right way that works for all people. Let your provider continue to use classic IPv6 addresses wherever it works better for them. But create geo-topological addresses so that people who want local multihoming can do so without breaking your brittle Global Routing Table.
Both of these requirements defy business sense,
If you really want to combine transport identifier and routing locator into a single "address", you give up a lot of flexibility. For routing to scale, addressing must follow topology, so in such a network architecture the term "topology independent address" (aka "provider independent address") is
It's easy to make statements like this in theory. But when customers come, cash in hand, with requirements like the above, most businesses find a way to negotiate terms. Not all business actors are greedy and stupid. And innovation is not likely to come from the dinosaurs who dominate the ISP space today. It will come from small upstarts and from customers themselves demanding simple effective multihoming without provider lock-in. In other words, small provider independent geo-topological address blocks that are fully routeable on the entire Internet, either as detailled prefixes in their home city, or as a city/regional prefix elsewhere. truly
an oxymoron.
In geo-topological addressing, the address DOES FOLLOW topology. Your problem is that you cannot see the forest for the trees. A provider independent address does not necessarily mean topology independent. --Michael Dillon
I looked at some of these models back in ~2000, but the dotcom boom ended and I didn't get laid off from my day job, so I didn't go trolling for venture capitalists, and my employer sold off their cable companies - since then, the market economics have changed a lot, and routers have started to support enough memory to keep up with the demand. The big questions about the dual-homed customer base are what kind of connectivity they really need - Primary/Backup, or Primary / Backup+extrabandwidth, or truly load-shared, and also what diverse topology is available at the bandwidth they need. For a reasonably large chunk of the ~Y2K market, the answer was "A T1 or two with cable-modem backup", and another chunk was "T3 or bigger, able to afford a telco or CLEC access ring", and most customers were more concerned about backhoe fade, which takes a long time to fix, than about ISP routing glitches, which were less common than 5 years earlier and usually had a much shorter mean time to repair. None of these solutions requires a World Domination Grand Master Plan agreed to buy everybody before it can be deployed - almost anything can start out with two carriers or a transit-buying service provider and then grow. One obvious business model to serve the smaller market was to start a "Slash-19.net", which would get a routable chunk of address space, buy transit from one or two colo providers, and use GRE/IPSEC/L2TPv3 tunnels to connect to the customer through whatever Layer 3 media is available, e.g. cable modems, and optionally use LEC frame or similar transport where available. In the emerging IPv6 world, a tunnel broker service could do something like this. And for equipment-cost reasons, you'd probably use PCs instead of routers as your tunnel servers. Another business model would be for a Tier 1 or Tier 2 ISP to do something similar, using a smaller chunk of their own address space, and using a tunnel server at one of their peering points (or colo space served by another ISP) to handle tunnels through the secondary carrier, such as cable modem companies. Making the addresses work well would require them to use the dual-homing address space for those customers' interfaces instead of whatever probably-geographical schema they use for single-homed customers. The cable companies would be an obvious ISP to do this - they've got control over the most common small diverse access methods, and most of them use PPPoE to connect to their customers so they've already got tunnelling. New wireless access ISPs could do much of the same business. Another model is cooperation between big carriers - if you're doing the N**2 pairs-of-carriers model, there are ~30-35 Tier 1 carriers in the US, so ~1000 address blocks would be enough (if it sounds like a cabal, too bad), and probably a similar but smaller number for Europe. Tier 2 players might need to arrange separate deals with one or more of their upstream Tier1s, so they might double their address space (still only adds ~10K routes), or else they might do an exchange point approach (e.g. somebody like Linx starts Diverse-Linx.) If somebody can get more than two Tier 1s to cooperate, they could do the geographic approach, which can make a major dent with ~50-100 cities in their market.
participants (4)
-
Bill Stewart -
Michael.Dillon＠btradianz.com -
Paul Jakma -
Vince Fuller