Test 2

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Modified: 

Name _____________

 

1. (10 pt)    Give the steps in computing the shortest path from A to F following the method listed in the text on page 354. Use the table below for the distance between each node.

    Distance
A B  
A G  
A D  
B C  
C D  
C F  
D E  
E F  
E G  
F H  
G H  


 

 

2. (5 pts) Given the table of delays between routers at left below and the network at right, compute the new routing table for D using distance vector routing.

    Delay
A B  
A G  
A D  
B C  
C D  
C F  
D E  
E F  
E G  
F H  
G H  
      
 To    A      C      E    New Router Table
A
B
C
D
E
F
G
H
0
 
 
 
 
 
 
 
 
 
0
 
 
 
 
 
 
 
 
 
0
 
 
 
   
   
   
   
   
   
   
   

3a. (10 pts) For cost table below left:

  1. mark the minimum spanning tree of the network at right for the routers with router I as the root,
  2. give the number of packets required for a broadcast from I to all other routers using the minimum spanning tree.
    Cost
A B  
A G  
A D  
A I  
B C  
C D  
C F  
D E  
D J  
E J  
E I  
E G  
E F  
F H  
G H  
G I  

3b. (10 pts) Using reverse path forwarding for the network of Question 3a:

  1. On an unlined, separate piece of paper, neatly draw the tree similar to the text on page 369, Figure (c) built for a broadcast from router I by reverse path forwarding assuming routers have just been initialized, that is they have no knowledge of other routers,
     
  2. Give the number of packets required for a broadcast from I to all other routers.

3c. (15 pts) Using the network of Question 3a:

  1. list the link state packets for the network,
     
  2. determine the minimum cost path from I to J using Dijkstra's Shortest Path Algorithm. Email the source program and any data used to: rwisman@ius.edu with subject line Dijkstra's Shortest Path Algorithm.
     
  3. give the routing table produced by I using link state routing.
     
     To     I Table
    A
    B
    C
    D
    E
    F
    G
    H
    I
    J
    		 
     
     
     
     
     
     
     
     
     
     

4. (20 pts) For the set of bridges, LANs and hosts at right above (circles are bridges, squares are LANs, and triangles are hosts):

  1. On an unlined, separate piece of paper, neatly draw a spanning tree of your choice for the LANs with bridge I at the root.
     
  2. Assuming the LANs are all 802.3 compliant, neatly draw the frame transmitted containing the message of the characters in your first name from host h1 with MAC address: 12:34:56:78:9A:BC to host h2 with MAC address: FE:DC:BA:98:76:54.
     
  3. Calculate the checksum for the data part of the frame (i.e. characters in your first name, use spaces for any padding needed in the calculation). A 32-bit checksum calculator can be obtained from http://www.erikburd.org/projects/crc32/index.html.
     
  4. Assuming bridges have just been initialized, that is they have no table information, give the table constructed by transparent bridges for h1 to send a message to h2.
     
  5. Update the bridge tables for a reply from h2 to h1.
     
  6. Describe the effect and means of recovery on your set of bridges and LANs should bridge I, the root, fail.

5. (10 pts) Suppose that you are connecting your residence to IUS over a 10 Mbps CSMA/CD LAN (not 802.3) using a medium that has a propagation rate of 200 meters/microsecond and no repeaters or other sources of delay. Show work for the following computations.

  1. What is the approximate distance between IUS and your residence in meters?
  2. What is the round trip time for a signal between your residence and IUS?
  3. What is the contention period?
  4. What is the minimum frame size?

6. (10 pts) 

  1. A network on the Internet has a subnet mask of 255.255..0. What is the maximum number of hosts it can handle?
     
  2. A large number of consecutive IP addresses are available starting at 198.16.0.0. Four organizations, A, B, C and D request , , and addresses respectively and in that order. For each, give the first IP address assigned, the last IP address assigned and the mask in the w.x.y.z/s notation.
     
  3. A router has the following (CIDR) entries in its routing table:

        Address/mask    Next hop

  1. 135.46.56.0/22    Interface 0
  2. 135.46.60.0/22    Interface 1
  3. 192.53.40.0/23    Router 1
  4. default               Router 2

For each of the following IP addresses, to what interface or router number does the router send a packet with that address arrives?

  1. 135.46.63.
  2. 135.46.57.
  3. 135.46.52.
  4. 192.53.40.
  5. 192.53.56.