Announcement

Final Lab internals is postponed to 18th December

Note

We will have Lab internals on 12th December.

Any one in the group may be asked to explain the demo of there projects.

And as usually there will be viva for everyone.

Every group must submit the Feedback before 12th December.

Group16_QuadMasters:Selective Repeat ARQ ppt

Schedule

Date	Group B Project
Nov 25	Selective Repeat ARQ Group 1, Group 2, Group 8, Group 12, Group 16
Dec 2	Stop and Wait ARQ (the left once)

Group16_QuadMasters:Selective Repeat ARQ

Features required for Selective Repeat ARQ

* To support Go-Back-N ARQ, a protocol must number each PDU which is sent. (PDUs are normally numbered using modulo arithmetic, which allows the same number to be re-used after a suitably long period of time. The time period is selected to ensure the same PDU number is never used again for a different PDU, until the first PDU has “left the network” (e.g. it may have been acknowledged)).
* The local node must also keep a buffer of all PDUs which have been sent, but have not yet been acknowledged.
* The receiver at the remote node keeps a record of the highest numbered PDU which has been correctly received. This number corresponds to the last acknowledgement PDU which it may have sent.

The above features are also required for Go-Back-N, however for selective repeat, the receiver must also maintain a buffer of frames which have been received, but not acknowledged.

Feedback

Name of Teacher

Options:

a. Yes always

b. Very Often

c. Sometimes(occasionally)

d. Almost never

e. Never

1. Does the teacher encourage active participation of students in class
2. Does the teacher have control over the class?
3. Does the teacher provide appropriate explanation to the doubts raised by the students?
4. Does the teacher have good knowledge pertaining to the subject?
5. Does the teacher give individual attention to the students?
6. Does the teacher expects the students to know beforehand the concepts that have not been covered?
7. Does the teacher speak irrelevant topics in class?
8. Does the teacher adhere to the lesson plan provided?
9. Is the teacher approachable to the students for clearing doubts?
10. Is the teacher biased towards certain students?
11. Is the teacher punctual to class?
12. Does the teacher put too much workload on the students?
13. Does the teacher give practical scenarios in order to explain theoretical aspects?
14. Is the proper evaluation of the internal by the teacher carried out?
15. Does the teacher give proper guidance is implementation of the projects/lab work?
16. Are the classes made interesting by the teacher
17. Does the teacher communicate well enough to convey what he/she is trying to say?
18. Does the teacher encourage students to participate in extra curricular activities?
19. Do you feel the assignments given by the teacher are of any help?
20. Does the teacher take into consideration the students point of view?

Some Good Problems

1. You are asked to measure the performance of telephone line of bandwidth 4Khz.When the signal is 10V , the noise is 5mV. What is the maximum data rate supported by telephone line?

 

2. A signal travels from point A to point B. At point A, signal power is 100W and at point b, the signal power is 90W.What is the attenuation in decibel?

 

3. Suppose that the signal has twice the power as a noise signal that is added to it. Find the SNR in decibels. Repeat if the signal is 10 times the noise power, 2ⁿ times the noise power, 10^k times the noise power.

 

4. Justify the statement “The maximum achievable modulation rate is twice the bandwidth”.

 

5. We have a channel with a 1MHz bandwidth. The SNR for this channel is 63.What are the appropriate bit rate and signal level?

 

Group16_QuadMasters:Selective Repeat ARQ

Applications of Selective Repeat ARQ

• TCP (Transmission Control Protocol):  transport layer protocol uses variation of selective repeat to provide reliable stream service
• Service Specific Connection Oriented Protocol:  error control for signaling messages in ATM network

Efficiency of Selective Repeat

• Assume Pf frame loss probability, then number of transmissions required to deliver a frame is:

• tf / (1-Pf)

Example:  Impact Bit Error Rate on Selective Repeat

nf=1250 bytes = 10000 bits, na=no=25 bytes = 200 bits

Compare S&W, GBN & SR efficiency for random bit errors with p=0, 10-6, 10-5, 10-4 and  R= 1 Mbps & 100 ms

Efficiency	0	10-6	10-5	10-4
S&W	8.9%	8.8%	8.0%	3.3%
GBN	98%	88.2%	45.4%	4.9%
SR	98%	97%	89%	36%

• Selective Repeat outperforms GBN and S&W, but efficiency drops as error rate increases

New Project Report Format

GUIDELINES FOR WRITING THE PROJECT REPORT
(5 MARKS)

REPORT FOR GROUP A PROJECT

1.  Introduction

2. Comparision of Tools

3. Steps to Configure and Result

4. Problems faced

5. Screen Shots of demo

6. Questions and Answers

REPORT FOR GROUP B PROJECT

1.  Introduction

2. Literature survey

3. Algorithm

4. Program

5. Results(output)

6. Limitations

7. Conclusion

If  their is some mistake in what i have posted please inform me-Hariprasad

Group16_RemoteLogin:Interactions Blog-Group A Project Q & A Session

Q) Whether the Operating System should be the for Remote login to happen?

Ans: Need not be Remote login does not depend on the Operating system used

Anwered by Hariprasad

Q) IP will be changing dynamically so how will remote login happen with a single IP

Ans: For each session there will be different  ip addresses  and therefore remote login  in different sessions may have different ip addresses

Answered by Hariprasad

Q) Can we remote login using other than ip address in telnet?

Ans:Need not be ip address always we can also use  host name for remote login

Answered by Deepakraj

Q) What is VPN network?

Ans: A virtual private network (VPN) is a computer network that is implemented in an additional software layer (overlay) on top of an existing larger network for the purpose of creating a private scope of computer communications or providing a secure extension of a private network into an insecure network such as the Internet.

Answered by Pavan.S