Assignment 10 (Last)

The assignment is due Sunday, August 1, 11.59 pm EDT. Submission Guidelines

  1. Programming problem: We extend the SIP capability by adding registration (REGISTER request) add Digest authentication (RFC 2617), in MD5 algorithm mode, as described in further detail in RFC 3261, Section 22.4. Only the 'auth' mechanism, not 'auth-int', needs to be supported. C code for MD5 and base64 is available; feel free to use other libraries in Java or C. You should test your implementation by getting an account at iptel.org. You can test your iptel.org account with the Microsoft Windows Messenger (not MSN Messenger!) and then later with your own client.

    With this addition, you now have a basic SIP-based IP phone that can place and receive calls. You should be able to register your user agent with iptel.org and then send an invitation to youraddress@iptel.org from the Windows Messenger client, causing your client to indicate an incoming call. You should be able to talk between two clients, e.g., yours and a friend of yours, both registered at iptel.org.

    You should include the test results, e.g., a log of the packets sent and received, in your homework submission.

  2. In class, we covered the Markov chain for the M/M/1 and similar queues. Draw the state diagram and then derive the state probability equation for the M/M/1/2 (at most 2 users in the system, i.e., one waiting), i.e., the probability that there are k users in the system. You should set up a set of linear equations (flow balance equations). Take into account that the flow into and out of a node has to be equal in steady state. Also, the probabilities for all states have to add up to 1.
  3. Assume a network of 10 routers, each running WFQ. (Thus, there are 11 links, including that to the receiving host.) The source has a maximum burst size of 1200 bytes and a maximum packet size of 600 bytes. The minimum service rate (g) is 1 Mb/s. The network sees packets that are up to 1000 bytes long. All links have a physical bandwidth of 45 Mb/s. Compute the maximum end-to-end delay.
  4. Review question: describe the differences between EF and AF.