Apologies for the abstruse British slang in the title, but Bob Frankston has excelled himself in framing the network neutrality and muni network debates. It’s simple: he’s just switched the metaphors of sidewalks (pavements) and local access networks. The absurdity of the situation becomes clear.
As Bob puts it, why can’t anyone see that it’s nothing to do with “networks” at all really — the moment you get beyond the central office and start worrying about discrimination between Google bits and MSN bits, you’ve already passed the bottleneck. Network neutrality is a mis-framed debate.
Another salient point: in a local access network with a star topology, there’s NO congestion. Ever. It’s only once someone hooks up a “service” that you have a rivalrous resource. That matters, because we don’t need to engage markets and the price mechanism for non-rivalrous resources. Once we’ve built the access, muni-like capital ownership isn’t an issue. I even wonder if this means a muni net should shy away from interconnecting people who are attached to the same central office/exchange? The logical answer is that they should not go beyond the physical access — no routing allowed (bar exceptions for emergency service use etc).
Now, where did I put my sidewalk smartcard pass and secure RFID shoes…
Posted by Martin Geddes at 11:24 AMTrackBack URL for this entry:
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"...in a local access network with a star topology, there’s NO congestion."
Actually, only if the star topology is a homerun star. If, instead, you have something like remote DSLAMs with T1s or metro ethernet carrying the traffic back to the central office, you get the possibility of congestion between the DSLAM and the CO - which is generally considered part of the "local access network".
Posted by: at July 21, 2006 03:03 PMIf I'm correct in guessing that a "homerun star" means each spoke of the star is a single span, unless all the services are in the hub (which may be what ``It’s only once someone hooks up a “service”'' where "someone" is not the access network operator, ie a leaf node), there will be congestion.
Once you accept that there will be congestion if services exist at the edge, the star topology loses its advantage and the benefits of bus and/or mesh (despite their inevitable contention and consequent congestion, and lack of home runs), particularly decentralisation, begin to be more appealing.
Hauling everyone's traffic back to what was once the billing point, the single point of inadvertent or malicious failure, when multiple routes (but not routing) would improve resilience, no longer seems the best solution for a municipal utility transport network.
After all, we don't all have individual footpaths running from our home to a single service center in the middle of town...
Posted by: at July 22, 2006 09:06 AMReading Bob's essay I was reminded of being accosted in Hyde Park London - the gentleman sold me a ticket for the deckchair I had foolishly occupied.
Posted by: at July 23, 2006 02:55 AMSorry this has gotten a bit long. But statemetns like Bob's really get on my nerves.
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Again I am reminded ludicrous how the QoS and control debates are. Two points spring to mind after reading Bob's piece (1) everyone who maintains that having QoS means that everyone is throttled is ehm, mistaken, to put it mildly. (2) using the analogy, no-one disputes sidewalks versus roads. One lane for the slow traffic and one for the fast. In my country you regularly have a lane between that, for bicycles, coming to three classes of service.
Martin, could you please explain to me how you come to the conclusion that there will be no bottleneck? There will ALWAYS be a bottleneck somewhere. The most likely place will be the first place where aggregation is done, as it is economically infeasible to buy as much bandwidth to the rest of the world as you are selling to you customers (say you are selling 1 million broadband accounts for 1Mb/s each, you will not be buying 1*10^6 Mb/s bandwidth. A star network will have the bottleneck where the star is connected to the rest of the world, unless no-one really wants to communicate with the rest of the world, much. (think peer to peer filesharing, assuming p2p software learns about the concept of nearby nodes vs far away nodes.)
There is a whole slew of applications that really can not live with the 20x over provisioned asymmetric broadband we have now in a world where broadband users are using their broadband more and more (so the utilization goes up and everyone suffers). My own DSL line sometimes has 10% loss these days, meaning the net is being used more in my area. This means VoIP is getting iffy and the telcos who are rolling it out need to do some QoS marking on the VoIP in order to get it to work.
Contrary to popular belief QoS for broadband IP networks is a means to have several kinds of bandwidth on the same line (something you cannot do on a road and hence the analogy breaks). If you are a proponent or a an opponent of QoS and think that this means setting bandwidth aside for applications and thus making it unusable for others full-timeyou are, again, ehm, mistaken.
Now the RIGHT way to do QoS is to schedule the several kinds of bandwidth (from best-effort for email, to high-bandwidth and guaranteed for video calls) over the same infrastructure. This bandwidth should be requestable on-demand by service providers who need more than the basic best-effort connectivity for their services. This will require some upgrades to the existing infrastructure but they ought to be recouped easily because of the value created by enabling an open(!) network that can deliver more applications than the broadband internet access sold now.
Now the math of scheduling QoS determines that it is easy to have something like 50%-60% of guaranteed real-time traffic of the network but becomes increasingly expensive when you want to take it to 80%-90%. So the cheapest way is to introduce the tech needed to deliver QoS and double the available bandwidth. This will lead to there being more best-effort bandwidth available if there are no video calls to carry, so QoS gives more rather than less bandwidth to the people who complain today that QoS will take ‘their’ bandwidth away and it give them the same amount of best-effort bandwidth in the presence of video calls.
There are people in this industry who like me have known of the shape of doing QoS right since the turn of the century, and even a few who like me know of the exact tech needed to do it. Why then does no one else seem to come to the same conclusion and rather fight over misconceptions?
No, I think you've missed the point Paul. It's before we get to any congestion or QoS is the part of the access network that is the unnecessary bottleneck. That bottleneck exists because of historical reasons (PTTs, AT&T) as well as market fugdes at privatisation. What's needed is a model where the users commission access infrastructure, and the state's role is to provide incentives to coordinated collective behaviour and take out transaction costs. The market can then deal with the upstream bit -- you still have to pay for an ISP, but do have a diversity of options and none are hostage to the access provider.
Posted by: at July 31, 2006 10:35 PMMartin. Technically I see two bottlenecks in, say, today's ADSL networks: (1) the bandwidth of the ADSL in quantity, quality and asymmetry, (2) the aggregating ATM switch and its uplink. The way LLU was fudged at the political level means that these are owned by the former monopolists and alternative carriers have no business case, that is a commercial bottleneck right there I agree.
However I think this has little to do with the analogy of the sidewalks, Quality of Service is a different subject.
My take on how this should be solved is similar to yours, but more concrete than you described here.
A fiber roll-out is inevitable. But an FTTH deployment is a near-monopoly, just try and find a way to economically justify building another one. So the fiber HAS to be owned by the government to prevent monopoly abuse leading to more bottlenecks, just like the roads, railways and other infrastructure a publicly owned.
Then the government needs to make sure that those who get a license to light-up these fibers will do so in a way as to provide maximum value to the users, so equal access of both users and service providers and sufficient bandwidth for all, if this is done right, is there a reason for a choice of operators? Probably not.
Now the government is notoriously bad at doing things like ensuring that the network operator does his best to supply what is needed. So we may need to stack the system a bit more before the politicians can mess it up. Just brainstorming here; one may envision running not 1 but 3 fiber trees when the streets are open. This will barely cost more because the main costs are in digging trenches and closing them again anyway. This will allow three licenses to be handed out in any particular area and this sows the seeds for competition.
Then the government only needs to make sure that:
(1) people can quickly and painlessly switch between network operators as they will basically deliver the same transport service.
(2) the network operator shall under no circumstance deliver any application services, such as telephone calls or internet access, as this would make it predisposed to favour its own services on its network and limit those of others.
Unfortunately the governments seem to be stuck in a pre-Internet mindset and supporting the economy by pushing FTTH to all homes and companies is not high on their agendas. So I am afraid we will end up with private monopolies and bottlenecks.
I hope EU commissioner Nelie Kroes and all the national governemnts are paying attention!