The Sympatico service is integrated within the new Bell Nexxia backbone network that spans across Canada and with links to the United States. This new core network is based on fiber optic technologies that has been built to support data transfer rates up to OC-12 (622Mbps). The Bell Nexxia network is truly world class.

The Sympatico service within Ontario and Quebec runs over the Bell Nexxia network. The network consists of Asynchronous Transfer Mode (ATM) and Packet over Sonet (POS) fiber optic links at OC-12 (622Mbps), OC-3 (155Mbps) and DS-3 (45Mbps) bandwidth rates.

A view of the Bell Nexxia core network can be seen at http://www.bellnexxia.com

The Bell Nexxia network in Canada is connected to multiple US carriers through multiple peering and transit connections in Chicago, Seattle, Toronto, Montreal and Vancouver. Also, New York and Palo Alto are soon to be added as major interconnection points. These interconnection points provide redundancy, high performance and reliable Internet network. We also deploy redundant equipment in our PoP (Points of Presence) sites as well as redundant PoPs in major cities for enhanced reliability.

The core backbone is actively monitored using the latest technology in network management systems. To ensure customer satisfaction and reliable service continuity, the Nexxia network is staffed 24x7x365 by our technical and network operation centre personnel. We employ efficient escalation procedures.

The Sympatico service also has 'High Speed Edition (HSE)' in its service portfolio. HSE is a leading edge service that utilizes Nortel's 1 meg modem product to provide dedicated Internet access speed up to 30 times faster than dialup modems. HSE also runs over the high capacity fully redundant Bell Nexxia backbone.












---------------


ATM is a cell-routed data link protocol which has similarities with ISDN, Frame Relay, and, surprisingly TCP/IP.  When an ATM 'end device' wants to send data to another ATM end device, it fragments data-link frames into 48 byte cells, and prepends a 5 byte header which includes a cell checksum, and the destination Virtual Path Identifier and Virtual Circuit Identifier.  The intermediate switches have switching tables which contain instructions to the effect of 'cell with VPI/VCI x/y and input interface z, gets output with VPI/VCI a/b and output interface c'.

ATM also supports quality of service, by specifying certain types of Virtual Circuit in part of the specification known as 'ATM Adapatation Layers.'  These, however, are unimportant here; all that's required is to realise that we're talking about Variable Bitrate Cell-Switched data, which meets the criteria of AAL5.

Now, the cell switching tables can be built in one of two ways.  Either statically, by hand (on each intermediate switch - this becomes something of a nightmare eventually); or by using ATM signalling to dynamically build virtual circuits between two end devices connected to the same ATM network.  In order for ATM switches to know which destination device a given source device is talking about, it needs some concept of addressing.

Enter the NSAP address.  This is usually 20 bytes long, and has the format (prefix).(station address).(selector byte).  The selector byte is almost always zero and is used to differentiate different ATM applications running on the same device.  We can safely ignore it.  The prefix is specified by the ATM switch the device is connected to, and has a variable length.  The E.161 standard specifies a 13-byte prefix length.  The station address is much like a LAN station address and is six bytes in length.

Now, after an end station registers with its directly connected switch, it sends a packet identifying its station address to the switch over well known VPI/VCI pair 0/16, which is referred to as ILMI (Integrated/Interim Local Management Interface.)  The switch then advises the end device of its prefix, and all is well.

Amongst themselves, the switches run a link-state routing protocol to advise each other of which prefixes they can reach.  Eventually the network converges.

Eventually, an end device wants to set up a virtual circuit to another end device, so it announces its intention to the switch via the ILMI mechanism.  Based on its routing table, the switch sends a similar request to its next-hop switch for the requested prefix, and eventually the connection request reaches the other end station.  After acknowledgements are sent back in the other direction, the switch announces the VPI/VCI pair for the newly-built circuit to the end device, and all is well.  Until the circuit is torn down (again via ILMI,) the VPI/VCI pair for the circuit functions identically to a hard-coded PVC.

Now, back to ADSL.  Since the entire network is built on ATM anyhow, why not simply connect your ADSL ISPs to the ATM network of whoever owns the physical copper, and let the end user initiate an ATM VC to their ISP of choice.  In this way, an NSAP address would function much like an 'ADSL Phone Number.'  You could either build the connection and then frame ethernet over it (much like ATM LANE, but without the complications,) or you could simply run PPPoA over the SVC.  This would fit in very nicely with the current 'dial up' model that most internet users are used to, albeit at higher speeds.

ADSL ISPs would need:

- ATM circuit into national carrier (as opposed to ISDN lines into national carrier for dialup modems)
- Slightly larger connection to the Internet (as opposed to what they have to support dialup).

As long as these two constraints are met, the whole thing would function flawlessly.

The only problem I can forsee with this method is that a user is likely to balk at a phone number which looks something like

47.0080c0.d00000.c0a0c0.470120.010044.3dc58e.00

but then, you could hide that from them with an Install CD.  The current VPI/VCI settings are hidden from them anyway.



A year ago, I signed up for Earthlink DSL ($50/month, free self-install package). My modem arrived within several weeks, and the connection worked fine right away. I'm over 10,000 ft from the teleco, yet I get over 1300/320 bps consistently. There have been no major outages, aside from the week following 9/11. I've been nothing but pleased with my service... although their customer support is not spectacular. Earthlink uses PPPoE.

Questions...
What about SDSL and IDSL? How are these functionally different from ADSL, and what makes them (or at least SDSL) superior? How about ADSL that does not use PPPoE? When does the bridged vs. routed option come in to play?

I've been thinking about switching to Speakeasy.net DSL because they offer multiple static IPs, allow servers (technically Earthlink does not forbid servers), and do not use PPPoE. What would be the ramifications of hosting one or several small websites over such a connection?




SDSL and IDSL by TunkeyMicket, 07/16/2002 01:52:21 PM EST (none / 0)
SDSL and IDSL by wesmills, 07/16/2002 01:47:00 PM EST (none / 0)
Broadband (4.00 / 3) (#20)
by TunkeyMicket on Tue Jul 16th, 2002 at 08:43:02 AM EST
(watford[at]uiuc[dot]edu) http://dorm.tunkeymicket.com


Broadband in the United States sucks ass unless you get lucky. I was lucky.

I live in the boonies of NC, my house surrounded by woods and few neighbors, quite the isolated area. We have cable via Time Warner, so when they started "beta" testing cable modems in our area, I jumped at the chance. In the beginning I could pull 6-7mbit down [almost a full megabyte] and push at a full 2mbit. These speeds were absolutely amazing. I could run game servers with ease, leave napster on 24/7, run an ftp/http suite, and still have enough bandwidth to download the files I wanted. My cable was this way for almost a year and a half. Then I went to college. At college I was on very very fast UIUC lines, and could pull the full megabyte and push nearly half a megabyte over the Internet. My Mecca was found. Arriving back at home I find that my cable does 20KBps max on the down and a lil over 10KBps on the up. WTF. Evidently Time Warner had stacked about 100 people on my local loop, when it used to be just me and my few neighbors. I guess the Road Runner auditors noticed that our small loop was using a large portion of the available bandwidth. They also stuck 2 more routers on the line, bringing my hop count to the nearest backbone to 4, from the previous 2. Internal pings between RR customers was between 10ms-15ms origionally. Now I would get 40ms-50ms pings to people in my neighborhood. I notice large amounts of packet loss at my gateway router. Ugh. The real slap in the face is RR's only way of fixing problems: Un-plug your modem, wait 90 seconds, plug it back in. Yeesh I could train a monkey to handle their tech support. They advertise speeds of 2mbit down and 512kbit up. 20KBps is much less than 2mbit, and 10KBps isn't quite 512kbit. I do understand that they don't have to provide me the advertised speed, just like Ford doesn't have to sell me a car which is like advertised. Oh wait, yes Ford does. So why the hell is RR any different? Hopefully a class-action lawsuit will force the fucks that messed up the broadband infrastructure to fix their mistakes.

To top it all off I can't get ISDN or DSL. Why? Because my neighborhood is so new they run fibre to the CO. Just peachy. What other alternatives does this leave me with? Satellite and Wireless. The first option is a negative, and the second option is pretty fookin expensive. I could also buy a burstable T1 or T2 line, but that would cost nearly 10 times the amount per month that my cable modem does, for only a minor increase in available bandwidth.

Broadband in the United States needs revising, because currently it sucks nuts.
--
Chris "TunkeyMicket" Watford


  Why ATM at all? (3.50 / 2) (#11)
by edison on Tue Jul 16th, 2002 at 06:46:23 AM EST



Giving the user control over what to use his access line for is all nice and dandy. But why do we keep bringing ATM up?

I am aware of the fact that most DSL equipment (unfortunately) uses ATM as the underlying transport technology.. To me, this is bad. Anything you can do with ATM can be done with IP and MPLS, and this is where we should be heading.

The goals you set out can be accomplished even if we skip the ATM layer.




Sort-of ... by cafeman, 07/16/2002 07:10:22 AM EST (3.00 / 1)
Skip ATM, go IP by edison, 07/16/2002 07:22:47 AM EST (4.00 / 1)
I disagree somewhat by cafeman, 07/16/2002 07:39:31 AM EST (3.00 / 1)
On .au and DSL by edison, 07/16/2002 07:49:02 AM EST (3.00 / 1)
Oz and the failing US Telcomm market (1.00 / 2) (#8)
by frankcrist on Tue Jul 16th, 2002 at 04:31:52 AM EST
(Oh_Me_Nips@qaip.com) http://finiki.qaip.com


I dunno shit about Oz, but I will say that I'm really pissed about the whole WorldCom falling out.  These dumb-fucks (says the Makers' Manhattan) could've had a huge DSL/ADSL market in the U.S. via the UUNet market.  Instead, they cooked the books and short-sold us like suckers.  Now, instead of BroadBand, I have an IRA down 30%.  Thanks, dickheads.

The devil tickled my pickle


  infrastructure (3.00 / 1) (#7)
by notAcoolNick on Tue Jul 16th, 2002 at 03:15:38 AM EST



+1. Interesting proposal.

However I have to say that I am highly skeptical about whole field.

Existing phone lines are perfect for vice. But not for broad-band. It only works on paper. Twisted pair will never be better than coaxial cable. And besides all that phone equipment when it was put together was never ment to be used for high speed.

Personally I still use 56K modem. ISDN is too littel bang for a buck, *DSL for me is not an option because I am too far from central office and I'll never give any more money to cable companies. First off all they squized out competition (they are buy default now are the owners of the "last mile"). And their own infrastructure sucks too.




coax vs. t/p by miles b, 07/16/2002 01:07:10 PM EST (none / 0)
Hee Hee by wiredog, 07/16/2002 08:19:07 AM EST (1.00 / 1)
For those who don't know the acronyms / background (4.80 / 5) (#5)
by cafeman on Tue Jul 16th, 2002 at 01:22:43 AM EST
(cafeman1@hotmail.com)


DSL = Digital Subscriber Line
ATM = Asynchronous Transfer Mode
POTS = Plain Old Telephone Service
DSLAM = Digital Subscriber Line Access Multiplexer
NSAP = Network Service Access Point

For those who are interested in how DSL works, here's a really good link. Also, there are multiple types of DSL, as shown here, of which ADSL is current the most common. Also, ATM is old school networking, created when a network meant a telecommunications network, not an IT network. I personally think it's a good thing to know where all this networking stuff came from (ie telecommunications). None of this easy gigabit stuff, ISDN, ATM, and Frame Relay all the way :)

Also, here's the obligatory link to Whirlpool, Australia's Broadband site (seeing as Telstra was mentioned in the article), and here's a previous K5 article on the state of broadband in Australia.

"No Silicon heaven? But where would all the calculators go?"



Acronyms by Beltza, 07/16/2002 07:14:17 AM EST (3.00 / 1)
Here are some more + explanations by cafeman, 07/16/2002 07:33:01 AM EST (5.00 / 1)
A few more clarifications by bsg, 07/16/2002 02:29:52 PM EST (none / 0)
That reminds me... by Mike Hunt, 07/16/2002 02:27:38 AM EST (3.50 / 2)
Minor points (4.33 / 3) (#1)
by cafeman on Tue Jul 16th, 2002 at 12:38:34 AM EST
(cafeman1@hotmail.com)


In your third paragraph you say the second layer can be PPPoE or PPPoA.  Isn't PPPoA actually the second layer, and PPPoE a third layer on top of that?  I was under the impression that PPPoE was effectively PPPoEoA, with the Ethernet as an intermediate translation layer for compatability and ease of configuration.  In order to use PPPoE, you need a bridge (either software or hardware), where with PPPoA, you go straight into ATM.  So, PPPoA would be:

TCP/IP
PPP
ATM
Copper

While PPPoE would be:

TCP/IP
PPP
ETH0
ATM
Copper

Correct me if I'm wrong ...

Also, DSLAMS are very expensive, and forcing two infrastructure implementations is very expensive and economically inefficient.  It focuses competition in high value areas, but leads to a complete lack of focus in low value areas (such as the bush).  Witness mobile phone coverage in regional Australia for a good example.  Not disagreeing with your main suggestion, just commenting that the third point is also really bad (for reasons you didn't seem to have stated).

Apart from that, I'm not technically competent to comment on the rest.  Sounds good though - anything to get rid of that ridiculous $129 - $189 registration fee.

"No Silicon heaven? But where would all the calculators go?"



Minor points with your minor points :) by Mike Hunt, 07/16/2002 12:43:38 AM EST (5.00 / 1)
Clarifications by cafeman, 07/16/2002 01:12:01 AM EST (3.00 / 1)
You're right by Mike Hunt, 07/16/2002 01:19:30 AM EST (3.00 / 1)
ADSL Done Wrong: Technological Impediments to Consumer Broadband | 26 comments (23 topical, 3 editorial, 0 pending)

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