Dr. Kathleen M. Kaplan's
Data Communication Networks
(Group) Quiz #5


The following quiz is on material from Chapter 7 of the text (similar to Exercise 11).

One packet of 4000 bytes segmented to 1000 bytes:
offset = 0
MFB = 0
offset = 1000/8 = 125
MFB = 1
offset = 125 + 1000/8 = 250
MFB = 1
offset = 250 + 1000/8 = 375
MFB = 0
Now, the second fragment gets sent to another network. The answers for your specific group is as follows:
  1. MTU = 200
    offset = 125
    MFB = 1
    offset = 125 + 200/8 = 150
    MFB = 1
    offset = 150 + 200/8 = 175
    MFB = 1
    offset = 175 + 200/8 = 200
    MFB = 1
    offset = 200 + 200/8 = 225
    MFB = 1
  2. MTU = 120
    offset = 125
    MFB = 1
    offset = 125 + 120/8 = 140
    MFB = 1
    offset = 140 + 120/8 = 155
    MFB = 1
    offset = 155 + 120/8 = 170
    MFB = 1
    offset = 170 + 120/8 = 185
    MFB = 1
    offset = 185 + 120/8 = 200
    MFB = 1
    offset = 200 + 120/8 = 215
    MFB = 1
    offset = 215 + 120/8 = 230
    MFB = 1
    offset = 230 + 120/8 = 245
    MFB = 1
    MTU = 600
    offset = 125
    MFB = 1
    offset = 125 + 600/8 = 200
    MFB = 1
Now, to put together, just get all fragments with the same: and put in order by offset 0, with mfb=1 to next highest offset, until mfb=0.
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To: Department of Systems and Computer Science web-site.

© Kathleen M. Kaplan 2000
Dr. Kathleen Kaplan, Howard University
Email: [email protected]