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| DSLAMs are in fact the problem in Bell data Folks
If you look at the data released, you'll see that congestion problems have dropped to totally minimal except at the DSLAMs. Their definition of "congested" is that one out of 200 15 minute tests of that link come within 10 and 30% of the capacity.
So if they eliminated a problem happening less than 0.5% of the time, that would add only a trivial load to the rest of the network. Especially because most of the "problems" do not affect any packets at all (there's still 10-30% of capacity to carry packets past the "congestion" threshold, which means most of them are getting through.)
So upgrading the DSLAM backhaul (where Bell identifies the problems) would easily alleviate the problem on that link while adding only an insignificant load to the rest of the network. Go look at the data.
It makes sense they don't have problems in the other parts of the network - carriers around the world are proving the network upgrades are practical and inexpensive - dimes a month on a service that sells for $30-$50 adds enough capacity to almost never have problems. (Katrina, 9/11 style events still likely problems.)
Bandwidth isn't free, but it's pretty darn cheap: 2-4% of what you pay for broadband. Switches and routers keep getting cheaper at a Moore's Law pace of 25-40% per year So you'd have to have bandwidth demand grow faster than 25-40% per user for the costs of (generally reliable) bandwidth to go up. The definitive data (Odlyzko, University of Minnesota) shows total growth of 40-55% from 2002 through 2008, or 28-35% growth per user.
There absolutely are congestion problems possible - cable upstream until DOCSIS 3.0 can get jammed - but if you look at the costs of providing bandwidth congestion are wired networks is inexpensively avoided 99+% of the time.
Dave Burstein
Editor, DSL Prime | |
 espaethDigital PlumberPremium,MVM
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Minneapolis, MN
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 ·Clear Wireless
| said by daveberstein:Their definition of "congested" is that one out of 200 15 minute tests of that link come within 10 and 30% of the capacity. That's because they're accounting for this nifty little thing called queuing delay. See: »www.cisco.com/web/about/ac123/ac···_ip.html
said by daveberstein:So upgrading the DSLAM backhaul (where Bell identifies the problems) would easily alleviate the problem on that link while adding only an insignificant load to the rest of the network. Go look at the data. This statement completely glosses over the fact that the DSLAMs have to plug in somewhere. The transport circuits are DSx or OCx today because they can be fed through narrowband and wideband digital access cross-connect switches (DACS) to be muxed up to fewer bigger circuits to be handled by the aggregation routers. The problem with upgrading DSLAMs to GigE (especially in remote terminals) is that Ethernet isn't muxable in a standard TDM DACS.
said by daveberstein:carriers around the world are proving the network upgrades are practical and inexpensive It's dirt cheap for backbone carriers to upgrade a few hundred connections in strategic locations where there are concentrated quantities of fiber. Shocking.
said by daveberstein:Switches and routers keep getting cheaper at a Moore's Law pace of 25-40% per year ... what?! You know what the MSRP was on a RSP720 for a Cisco 7600 in 2003? $28,000 You know what the MSRP is on an RSP720 today? $28,000 Interface costs have come down marginally, but some of the gains aren't quite what they seem. In 2003 you could purchase a WS-X6704 4-port 10GigE line card for the 6500/7600 and it would run you about $22,000 MSRP. Today you can purchase a WS-X6716 16-port 10GigE line card for $40,000 MSRP. Huge reduction, right? The problem is the slot capacity on the 6500/7600 is 40gbps per slot, so that 16 port card only adds additional interfaces but not additional capacity; it's 4:1 oversubscribed into the backplane. The same trend can be seen in equipment from every network vendor out there, when your interface cost goes down dramatically you're paying less because you're getting less. | |
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