Tuesday, July 28, 2009

[AIT09] ARQ Transmitter

This question is from Thanapol, 107929.
  1. What is responsibility of tARQ_ in ACK passing?
  2. What is the base class of ARQRx and ARQTx ?

Sunday, July 26, 2009

[AIT09] TCP Agent

This question is from Rujipol:

  1. Why does a TCP protocol need 3-way handshake? When does it being used?
  2. What does functionalities that TCP have that UDP does not have?
  3. What does variable "reason" in ~/tcp.h do? When does it being used?
  4. How many error control mechanism does TCP have? What are they?
[I suggest you to answer one question only]

[AIT09] Packets

This question is from Rujipol.

  1. How do we initialize the packet? What if we didn't initialize packet, what will happened?
  2. How do we deallocate a packet?
  3. What is the purpose of having packet header, and who is responsible for configuring the packet header?
  4. What is the actual data type of enum?
  5. Who is responsible for packet construction?
  6. What are two main parts of protocol specific header?
[I suggest each of you to answer one question only]

Friday, July 24, 2009

[AIT09] Update assignment submission

Dear all,

Please find status of your assignment submission in Here. The last day that you can submit the assignment is Jul. 29, 2009.

Teerawat

Tuesday, July 21, 2009

[AIT09] RTO

This question is from Shujaat.

1. What is the main difference between Bounded and unbounded RTO?
2. Which one does TCP use? Why does it choose that choice?

[AIT09] Connector

This question is from Thein Tun Aung

  1. What are the main variables of class Connector?
  2. Which ones are the pointer?
  3. Where do they point to? Is the object they point to an abstract object? If so, how?
  4. How do we fit the connector to a class composition framework?

[AIT09] Assignment Status

Dear all,

Here is the current status of assignment submission. Please check your own status. We have overall 9 assignments.

Best,
Teerawat

[AIT09] Assignment

Hi all,

I marked few assignments. I left your assignment on a desk of the Hallway, where you hand in assignment for other courses. Please go and pick up.

See you on Saturday,
Teerawat

Monday, July 20, 2009

[AIT09] Queue

This question is from Thein Tun:

How do you get the length of the queue ? Can you give examples of different types of queue?

[From Teerawat: Do not give more than one example per person]

Thursday, July 16, 2009

[AIT 09] HashClassifier

These questions are from Nakrop:

1. What are the differences between PortClassifier and HashClassfier?
What are their the based classes?
2. How important is a hash table is important to a hash classifier? Why? What information is stored in the hash table?
3. In the implementation of function classify(p)of class DestHashClassifier, what does the statement "set_hash(0,d,0,slot)" do?
4. How is OOP used to implement function hashkey(...) of class HashClassifier?

[AIT 09] OTcl, Route, and TCP

This question is from Muhammad Hasanain Chaudary:

1. What is the Role of keyword “self” in the OTcl?
2. What is the instproc (and what is the associated class) used to compute the optimal route in NS2?
3. What’s the difference between Fast Retransmit and Fast Recovery? What is their relationship?
4.Is there any drawback of TCP?

Wednesday, July 15, 2009

[AIT09] Classifier

This question is from Nakrop.

1. What are the based class of class Classifier?

2. What are two key variables of the C++ class Classifier? What are their purposes?

3. "Function classify(p) is the most important function of a classifier"
Do you agree with this statement? If you agree, please give your reasons.

4. What are the default values of shift_ and mask_ ?
Which function use these variables?

Monday, July 13, 2009

[AIT09] New Lecture Notes

Guys,

I just post a new lecture note on the website. I also fixed the broken file for chapter about UDP. Please have a look at

http://www.ece.ubc.ca/~teerawat/NS2.htm

Sunday, July 12, 2009

[AIT09] instvar classifier_ and next_rtm_ of class RtModule

This question is from Wattanadej

1. Why the instvar classifier_ and next_rtm_ of RtModule(OTcl) are not bind with the variable classifier_ and next_rtm_ of the compiled class(C++)?

2. What is the C++ class corresponding to the OTcl class RtModule?

[AIT09] RTT and RTO for TCP

This question is from our friend Shujaat

Suppose we have average RTT of 1.5 ms, and RTT variation of 0.5 ms. Suppose further that the next RTT sample is 3 ms.
1) What is the average value of RTT corresponding to the last RTT Sample above.
2) What is the value of RTT variation
3) What is the value of RTO

[AIT09] Output Queue

This question is from Thein Tun Aung:

How is an output queue of a node implemented ?
What will happen if the buffer capacity of output queue is exceeded ?

Friday, July 10, 2009

[AIT09] How to create a two-way TCP

This question is from our friend Shujaat

In our course we have studied TCP Agent for one way transmission by
sender (which obey different congestion and error control
techniques)and sink(receiver). If we want to transmitt in two ways. Is
is possible to transmit in 2 ways in NS2?
If possible then how?

Thursday, July 9, 2009

[AIT09] Addressing in NS2

This question is from our friend Hasanain.

The question is
  1. What is the address format in NS2?
  2. Where do we store (IP) address?
  3. How do we store the IP address? (using what function or instproc?)
Any comments?

Wednesday, July 8, 2009

[AIT09] A Welcome Message

Welcome, everyone. As we'll be discuss in the class, this would be the place where we discuss about NS2 course. The purpose is to have you all participate in a meaningful way. Here is how it works.

  1. You send me an email stating problems or questions you have.
  2. I select questions and post the selected questions (with title beginning with [AIT09] and label AIT09) on the blog. The selected question would earn marks.
  3. You help each other by trying to commenting or answering the question. Each thoughtful comment and answer earns marks. The meaningless comments such as "I think so" do not earn marks.

Try to come back here as often as you can. You know, it is easier to comment if you read the discussion first.

Good Luck... Teerawat