NC State Scientists Develop Breakthrough Internet Protocol

NC State Website ^ | 15 March 2004

[Montfort]

Soon after September 11, 2001, I rented five days on a rack of Cisco equipment at NC State early on in my preparation for a top Cisco Cisco certification (CCIE), which I achieved in August 2002. It was a very educational experience. They had a knowledgeable grad student who was helpful. NC State has lots of other IT lab equipment and many continuing education programs. All-in-all, I came away with a favorable impression of NC State.

[newgeezer]

I don't know what they did, but Mediacom upgraded the system a month ago and it doubled my bandwidth. (I think they said it would go 5X; maybe that's still to come. ;o)

[Mr. Bird]

I have family all over the world and we're all slowly getting webcams for our home PC's. For that kind of use (real time video and audio), is there a significant difference between the two? I understand that conversations will rely on the other person's connection as well?

[balrog666]

I'm getting 1.5 - 2.0 Mbps on cable.

That's about what I get at home too.

Then I bought cable access for a business. What a ripoff! They charge twice as much for the minimum business service for much less bandwidth. All they do is clamp it and try to extort more money. I told the bastards cable company to rip it out and then I got DSL. It gets about 25% of my cable speed at home at about the same cost.

[balrog666]

I have family all over the world and we're all slowly getting webcams for our home PC's.

Some of the local daycare centers have their rooms wired for cameras so parants can check in all day and see what's going on with their kids.

It won't be long before we can glue a camera on a baby at birth and record his entire life as it unfolds.

[js1138]

DSL is generally going to be a better fit for small business. You get guaranteed bandwdth, and you can get the upload bandwidth you need by paying more. My company has 5 static IPs for about $99 a month. we only need two, but the design of subnets allows only packages of one and five (actually three and seven, but two are not available to the user).

[Myrddin]

Phil Karn originally came up with the RTT calculations for TCP. TCP waits for the remote system to send data. After some period, it resends the request on the assumption that the prior request failed to reach the remote system. The RTT calculation tries to make an optimal estimate of when to timeout and make another request. Requesting too soon doesn't help...the data may be "in flight". Waiting too long causes the network to be idle when it could be doing some work.

The RTT approach was invented to solve communications between to LAN segments that are bridged by slower facility. The RTT algorithm tweaks a self-pacing aspect of TCP to keep the data moving at the optimal pace for the end-to-end connection.

Mike Karels also made some related contributions to the bridged LAN scenario. The maximum transmission unit (MTU) is typically 1500 bytes on an Ethernet. The old 56 kb lines of the Arpanet had smaller MTU values. That required fragmentation of the IP packets enroute ane reassembly at the destination. The frag/reassemble logic kills throughput. Mike approached the problem by doing a binary backoff of the MTU until throughput improved. The improved throughput was an implicit indication that the MTU had been adjusted downward enough to stop the IP level fragging.

This new protocol seems to be aimed at solving the inverse problem that RTT addressed. Two LAN segments connected by a much faster facility. I question whether this really belongs in the guts of TCP, or is more appropriately addressed in router equipment at the edge of a LAN. The large Ethernet packet (65 kbytes) work that Van Jacobson did on supercomputers was a real boon to the world of people moving massive amounts of data.

[newgeezer]

For that kind of use (real time video and audio), is there a significant difference between the two?

As far as I know, the typical low-grade webcam service you mentioned should be possible with any DSL or cable service; many or most of the variables hindering that scenario are outside your (and your provider's) control.

If both cable and DSL are available in your area, I'd think competition would cause one or both of them to be running a free installation promotion. But, watch out for any minimum length of service clause so that, if you don't get satisfactory results, you can drop their service without a retroactive or pro-rated installation fee.

As for cable, Best Buy et. al. often sell free-after-rebate cable modems, when you sign up for service (nearly free for existing customers). Ask your cable provider whether the specific model will be compatible and how much that'll save you ($5 or $10/mo).

[SamAdams76]

25 years from now, we will be able to download every piece of music ever recorded in less than a minute. And we will still have plenty of space left on our hard drives to download every movie ever filmed.

The only drawback is that Windows 2028 will have things slowed down to a crawl, but Bill Gates IV promises that the upcoming Windows 3031 will have significant improvements in speed, taking full advantage of the 512-bit processors of the day. Also, Windows 3031 is expected to have security enhancements as well.

[Centurion2000]

bump for later

[general_re]

DSL is generally going to be a better fit for small business. You get guaranteed bandwdth, and you can get the upload bandwidth you need by paying more.

I don't know where you are or who your provider is, but around here Verizon doesn't guarantee squat for business DSL, either in term of uptime or in terms of bandwidth - and I'll bet money that they're typical in that respect among other DSL/cable providers. If yours does, I would say it is by far the exception and not the rule. Mostly, if you need SLA's, you can pretty much forget business-class DSL or cable, and skip right to fractional T1...

[balrog666]

No Verizon here in Florida. It's Sprint or BellSouth.

I was on a fractional T1 a few years ago at a small office of a very large company (some contractual requirement). It cost over $700/month! Eventually the price went down to $249 or $429/mo or something. And what a pain it was when it went down - you never got the same tech twice and none of them had ever seen it before! It's replaced now with a single cable connection.

[general_re]

Well, BellSouth specifically disclaims any minimum level of service on their webpage, but that's the real difference between the two tiers - with T1, you get guarantees, which is why it costs a whole lot more than DSL or cable. E.g., Covad's standard T1 SLA guarantees 99.99% monthly uptime, which translates to less than five minutes of down time per month, and they guarantee packet-level performance in terms of maximum transit time. And good luck getting that from DSL or cable - you may have uptime of 100% at a blazingly fast rate so far, but BellSouth will be the first to tell you they don't owe you a thing if you have a week-long period where your connection is slightly faster than a 14.4K modem, which they would if you had a real dedicated connection - you pay more because if your service falls below that minimum level, you have a contract that spells out exactly what your remedies are, so there's no argument about that sort of thing when there is an interruption, no trying to sweet-talk them into giving you some sort of a credit. And hopefully someone in your previous office was making reference to that SLA with the problems you mention you were having before.

This is not to say that there's no place for business-class DSL or cable in the world - I'm sure there are lots of people it's perfectly suited for - but there are trade-offs that come with that low price. If you just need it for interoffice email and internet access for your users, then it's probably just fine. If you're running your own e-commerce business through your own dedicated servers, such that every second of downtime costs you money for lost sales, or something like that...you may want to skip the cable connection ;)

[Future Snake Eater]

Yeah, it's a really good school. I'm very glad I've had the opportunity to go there. I've learned a lot, I've made life-long friends, and I even met my wife there!

[balrog666]

If you just need it for interoffice email and internet access for your users, then it's probably just fine.

That's about it there.

[Moonman62]

And what a pain it was when it went down - you never got the same tech twice and none of them had ever seen it before!

They all belong to the CWA and the company was a monopoly (the worst of both worlds). Bellsouth was our vendor and we were one of their biggest customers. It was tough even for us to find good techs, and we had to constantly hassle management to get access to the techs that knew what they were doing. And when a new technology was involved, even that didn't work. We usually had to tell them how to do their jobs.

[justlurking]

So what? My cable modem service makes most DSL connections seem lethargic! ;O)

My DSL is spec'ed at 6 Mbit/sec downstream, and I'm observing 5 Mbit/sec downstream in tests.

What are you getting from your lame cable modem? :-)

[newgeezer]

Been there, done that. Let's move along, shall we? :-)

Besides, I'm guessing you can't do that for 40 bucks a month. :-P

[mikegi]

My DSL is spec'ed at 6 Mbit/sec downstream, and I'm observing 5 Mbit/sec downstream in tests.

What DSL provider are you using??? Bellsouth only offers 1.5 Mbps. My cable modem is 3 Mbps down and 256 Kbps up. I routinely get 2.8 to 2.9 Mbps download speed. I'm a happy camper, especially when I download beasties like MikTEX (230 MB file).

One misleading claim that dsl supporters make is that dsl doesn't share bandwidth. That's true only for the line from the dslam to your house. Upstream of that point, the bandwidth is shared.