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What it will take to shift the Net
page 3:  How broadband will change the Net

UT: Will data then have to slow down to hop between networks and then pop back up again?

Cerf: It would probably have to slow down to interfaces that are OC-48, OC-192 [9.6 gigabits per second], 10-gigabit-per-second channels. That's not too bad on an internetwork basis.

Keep in mind that the reason that you might find yourself having to carry such huge loads is that you might have a large number of other ISPs hanging off of you that are pumping traffic in and out.

UUNet specializes in wholesale Internet services, so that's an example of the network where you'd see the need for this sort of super-high-speed optical capability. But a smaller network might not need that capability quite as early.

Also, the traffic between any particular pair of Internets isn't necessarily in the terabit range. Between a particular pair of nets, a 10-gigabit link today is more than most internetwork transfers require. The highest bandwidth connections that I can think of right now tend to be up in the OC-48 range -- 2.4 gigs between a pair of networks is a lot of traffic.

Now, we have customers that are up at those speeds, but not very many of them. Microsoft (MSFT), for example, needs that kind of capacity, especially every time it releases a new operating system. So you're right that it would slow down in some sense, but I don't think it would be a bottleneck, because the traffic requirements between the networks tends to be not quite as huge as terabits yet.

How broadband will change the Net

UT: We hear a lot about broadband. Is this going to happen? Broadband doesn't seem to have a purpose yet. It floats around as if it were a done deal and people will actually have businesses they can hang on it.

Now, MCI must be thinking that there's going to be some demand for services that will take more bandwidth and different character of data than you're dealing with now. Not only do you have to grow the traffic 10 times a year or so, but you're dealing with different kinds of traffic.

Cerf: I know what you mean. It's not uniform. There are so many little facets to this. It's interesting. First of all, there is just the natural proclivity of people to send more information to each other when they can.

Everyone who pays attention to email has probably noticed that the average email message has gone from three thousand to thirty thousand characters over the last couple of years, and the reason for that is attachments of various kinds, whether it's JPEGs or video clips or Microsoft Excel and Word files. But it's an increasingly common experience to have attachments that take a whole lot of bits.

My kids were at home during the holidays and I wandered in one weekend and they announced that they had just finished downloading a gigabyte of stuff, and I said, "A gigabyte?" And they said, "Yeah! What's the big deal?" I said, "My goodness, I used to think a megabyte was a big deal."

UT: Beyond downloading software and media, what do you do with a high bandwidth connection?

Cerf: Well, you know, the reason that people want the bandwidth is not because they have a continuous demand, and it's not because they want to suck in huge amounts of stuff. What they would like is to get responsiveness.

For instance, if you have a gigabit per second or even, you know, a few megabits per second at the edge of the Net, it doesn't take very long to pull in a Web page. The issue is whether I can make this feel like a really interactive medium. Today it sort of is, and it sort of isn't, depending on the data rate.

UT: Typically, high bandwidth connections are also characterized by always being on.

Cerf: Well, always-on is very attractive because now you don't have to go through this ritual to get connected. And that means you can be a little bit more casual, I think, about using the network's resources.

You have devices that are always on the Net and you sort of just turn to them and do something -- it's like the telephone in a way. You pick up the phone and you get a dial tone. You don't wait. You don't have to log in, you know, you just dial a number and that's it.

UT: How does that change how an ISP deals with that customer?

Cerf: It will probably increase the rate at which the customers do interactions. It will increase the bandwidth that we need to carry in the backbone. It'll increase the total number of Internet addresses that have to be available at the same time.

Currently, people dial up, get an Internet address assigned, then they hang up and the address gets reassigned to somebody else. But dedicated connections and wireless connections have the characteristic that they consume IP address space and they keep it for long periods of time.

That's one of the reasons I'm so concerned about IP Version 6 getting going, because I'm concerned that we are going to run out of Version 4 addresses.

Additional Article Pages:
1. What it will take
2. So the backbone becomes...
3. How broadband will change the Net
4. The promise of V6

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