INT20CN Computer Networks

Tutorial #14

1. What is a leased line? Why is this considered an outmoded term nowadays?

2. What is meant by the term peering in the context of Internet Network Providers?

3. What is meant by the term Basic Carriage Service (sometimes called a Telecommunications Service) in the context of a full-time Internet connection?

4. Two aspects of a generic ISDN service which have been emphasised by the marketing people are dial on demand routing, and bandwidth on demand data transfer. What do you think these terms refer to? A Telstra local ISDN data call in Australia has a flagfall cost (day rate) of 20 cents (which includes the first 180 seconds of the call) plus 0.05 cents per second after 180 seconds has elapsed. Under what conditions do you think it would be reasonable to configure a local-call ISDN-based system to use "dial on demand" and/or "bandwidth on demand"?

5. What is the attraction of a frame relay telecommunications service over an ISDN service at the same "port speed"?

6. Imagine that you (as a graduate of this subject) have been asked to advise a small Australian business on establishing a permanent connection to the Internet. As part of your work, you decide to investigate the performance and price options available from Telstra, the dominant telecommunications (and Internet Service) provider in Australia. Before you attend this tutorial class, check out Telstra's Bigpond Direct Web pages, and be prepared to answer the following questions:
   1. Telstra splits Bigpond Direct (see also here) pricing into four components. What are they? You're excused if you can't immediately see what the fourth one is...!
   2. What are some of the options for the "Basic Carriage Service"?
   3. You should have discovered that one of the options for Basic Carriage Service is a dial-in modem link. Why is this a particularly attractive option?
   4. Some (all?) of Telstra's pricing options for Bigpond Direct have a data volume component. What does this mean, and which ones have this "feature"? What is the particular disadvantage of this pricing model in a business context? Does it have any advantages? Do any of the pricing options not have a volume component?
   5. VERY Hard question: Telstra's OnRamp XPress has some attraction as a Basic Carriage Service for a full-time Internet service. What would the minimum monthly cost for a business using this service for its Internet link, including the Bigpond Direct charges? Don't even try to incorporate the Back Channel Tariff stuff into your calculations! NB: I don't seriously expect you to do this -- I've tried and failed myself! However, if you're an Accounting Major you might find it fun to try.
   6. Research and extension question: What other issues will your client business have to have in place in order to establish a full-time "Internet Presence"?

7. In Australia, it's possible to purchase (in some capital cities) a full-time ("always on") Internet service from (eg) Optus@Home which doesn't separate the Basic Carrier service from the Internet service in the same way as Telstra does, and which doesn't have a data volume component -- there's simply a single monthly charge. How can they do this? Discuss. Note: this service is also not terribly useful for business-style permanent Internet connection. Why not?