Midterm II -- Networking Among the Greats

1. Suppose I want to send video over the internet. This is not real time video, but delayed video. I want the whole video stream to get there in it's entirety. What protocol should I use. (pick one)
   a) IP
   b) TCP
   c) UDP
   d) ICMP

2. What is the bandwidth and latency between euclid.nmu.edu and clarinet.dcs.uky.edu? Show work!! Bandwidth: ____________________ Latency: _________________
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

3. Which probably takes more code in the operating system to implement, TCP or UDP?
   _____________________________

4. Suppose a TCP connection is in the "slow start" phase. The current congestion window goes from (10,000-12,000). The window advertised by the receiver goes from (10,000 - 20,000). The maximum segment size is 500 octets. Which bytes can be sent in the next segment? ___________________________________________

5. What is the value of the congestion window after the ack for the bytes above is received? ___________________________________________

6. What does UDP do if it does not receive an ack for a transmitted packet?
   a) Retransmit after a timeout.
   b) Signal an error to the sending application.
   c) Send a packet with SEQ=x+1, FIN=x.
   d) None or all of the above.

7. A fiber optic link has a 99% chance or getting a packet through successfully. The maximum packet size is 1,000 bytes counting the header. The latency is 12 milliseconds. Counting the overhead of starting the connection, sending the data, and destroying the connection gracefully, what is the maximum latency that an application can see between sending the data and getting a reply? Show all work?
   
   
   
   
   
   

8. What is the minimum number of packets needed to send the first byte of TCP data. Establishing the connection counts, but releasing the connection does not.
   _____________________________

9. Suppose a receiver gets packets containing bytes (1-100), (101-200) and (301-400). When the receiver next gets bytes (201-300), what TWO should it do?
   __________________________________________________________________________________________________________________________________________

10. As a sender you keep sending packets, but a high percentage of them are not acknowledged on the first sending. What should you do? (pick all that apply)
    a) Reduce your congestion-window-size.
    b) Increase your time out value.
    c) Transmit smaller packets.

11. You have an IP number that you wish to send to. However, you've never sent to this IP number before, and don't know the Ethernet address. What should you do?
    __________________________________________________________________________________________________________________________________________

12. Does telnet use TCP or UDP? __________________

13. Give one reason why a router that sees multiple fragments of the same IP packet should not combine them:
    _____________________________________________________________________

14. Give one reason why a router that sees multiple fragments SHOULD combine them:
    _____________________________________________________________________

15. Suppose I want to send 50 bytes of data. The transmission is successful. Ignoring any ack's or ARPs, how many bytes does each layer send?
    TCP _________________________
    IP ___________________________
    Ethernet ______________________

16. Lost TCP ack's do not necessarily force a retransmission. Explain how this can happen? ______________________________________________________________
    __________________________________________________________________________________________________________________________________________

17. Two routers have routing tables show below. After exchanging routing info one time, what does the new route table for 'A' look like?

    
    HOST A HOST B

    Host	Dist	Via	Host	Dist	Via
    Gaag	10	Router1	Gaag	8	A
    Bine	10	Router1	Bine	12	Router1
    Aki	Inf	B	Aki	7	Router1
    Waabooz	10	B	Waabooz	10	A

    
    
    
    
    
    
    
    
    

18. In your mail program, you used system calls like socket(), bind(), and others. Did you make a TCP, UDP or IP socket? ______________

19. Calculus!! What does this expression evaluate to? ___________

    lim _x->2 17