INT21CN Computer Networks

Tutorial #16

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?
   1. In the diagram in the lecture, which of the links constitute peering relationships and which are "provider-client" relationships?
   2. Describe a path (or route -- ie, a sequence of two or more links) through the given diagram over which packets would ordinarily be expected to flow. Now describe a route over which packets would not, as a matter of commercial policy, be expected to flow. Discuss.

3. What is a POP in the context of Internet Service Providers?

4. In the lecture it was mentioned that Australia was one of the few markets where Internet access charges included either a data volume charge and/or a monthly "cap" on downloads. This was contrasted with, for example, the USA where access has traditionally been charged purely on "pipesize". Explain what each of these terms mean, and discuss the issues involved.
   Note: this may be changing, and it seems that USA pricing will possibly converge with the Australian model over the next few years.

5. As mentioned in the lecture, Telstra in Australia separates costing for "Basic Carrier service" from that for "Internet Service" for full-time ("Always On") Internet access.
   1. What is meant by the term "Basic Carriage Service" (sometimes called a Telecommunications Service) and why does Telstra separate it from Internet service?

   2. It's possible to purchase (in some Australian capital cities) an "always on" Internet service from (eg) Optus@Home, a competitor of Telstra, which doesn't separate the Basic Carrier service from the Internet service in the same way as Telstra does. Why/how can they do this? Discuss.

6. What is the attraction of using a modem for full-time business Internet access? What are some likely disadvantages?

7. What is the difference between ADSL and SDSL Internet access technologies? Which of these is likely to be more appropriate for home Internet access, and which for business access, and why?

8. What is the difference between a frame relay telecommunications service and an ISDN service at the same "port speed" -- say, 2Mbps (E1)?

9. Research: One characteristic of a full-time business connection to the Internet is (at least one) static IP. Discover what this means, and why it is (usually) necessary. What is the alternative, and why is it considered acceptable for home access?