WSU - CS 3705-0 - Spring 2006 - Vincenzo MAGGIO

Ethereal Lab IP

This are the traceroute results:
a)  with packet length 56 
--- 04/16/06 15:04:02 Mountain Daylight Time
--- looking up host gaia.cs.umass.edu
--- traceroute to gaia.cs.umass.edu [128.119.245.12],
    30 hops max, 18 byte packets

  1.  *  
  2  [  68.87.170.141]  68.87.170.141  11 ms  
  3  [   68.87.170.17]  68.87.170.17  31 ms  
  4  [    68.87.170.9]  68.87.170.9  9 ms  
  5  [  12.117.148.21]  12.117.148.21  17 ms  
  6  [  12.122.82.158]  12.122.82.158  42 ms  
  7  [  12.122.12.133]  tbr2-cl31.sffca.ip.att.net  42 ms  
  8  [   12.123.13.69]  ggr1-p370.sffca.ip.att.net  51 ms  
  9  [  64.200.151.17]  sntcca4lcx1-pos4-3.wcg.net  46 ms  
 10  [  64.200.149.49]  sntcca1wcx2-pos2-1.wcg.net  44 ms  
 11  [ 64.200.240.181]  dnvrco1wcx3-pos14-0.wcg.net  68 ms  
 12  [ 64.200.240.122]  brvwil1wcx3-pos2-0-oc192.wcg.net  63 ms  
 13  [ 64.200.240.254]  nycmny2wcx3-pos14-0-oc192.wcg.net  92 ms  
 14  [ 64.200.240.246]  spfdma1wce1-pos4-0.wcg.net  85 ms  
 15  [   65.77.95.162]  65.77.95.162  99 ms  
 16  [  128.119.2.193]  lgrc-rt-106-8-gi1-6.gw.umass.edu  93 ms  
 17  [  128.119.3.153]  128.119.3.153  90 ms  
 18  [ 128.119.245.12]  gaia.cs.umass.edu  99 ms  

--- traceroute statistics for gaia.cs.umass.edu
    18 packets transmitted, 17 received
    round-trip time (ms) min 9, avg 57, max 99
b)  with packet length 2000 
--- 04/16/06 15:04:11 Mountain Daylight Time
--- looking up host gaia.cs.umass.edu
--- traceroute to gaia.cs.umass.edu [128.119.245.12],
    30 hops max, 18 byte packets

  1.  *  
  2  [  68.87.170.141]  68.87.170.141  9 ms  
  3  [   68.87.170.17]  68.87.170.17  8 ms  
  4  [    68.87.170.9]  68.87.170.9  13 ms  
  5  [  12.117.148.21]  12.117.148.21  19 ms  
  6  [  12.122.82.158]  12.122.82.158  56 ms  
  7  [  12.122.12.133]  tbr2-cl31.sffca.ip.att.net  44 ms  
  8  [   12.123.13.69]  ggr1-p370.sffca.ip.att.net  41 ms  
  9  [  64.200.151.17]  sntcca4lcx1-pos4-3.wcg.net  63 ms  
 10  [  64.200.149.49]  sntcca1wcx2-pos2-1.wcg.net  42 ms  
 11  [ 64.200.240.181]  dnvrco1wcx3-pos14-0.wcg.net  95 ms  
 12  [ 64.200.240.122]  brvwil1wcx3-pos2-0-oc192.wcg.net  63 ms  
 13  [ 64.200.240.254]  nycmny2wcx3-pos14-0-oc192.wcg.net  93 ms  
 14  [ 64.200.240.246]  spfdma1wce1-pos4-0.wcg.net  85 ms  
 15  [   65.77.95.162]  65.77.95.162  88 ms  
 16  [  128.119.2.193]  lgrc-rt-106-8-gi1-6.gw.umass.edu  88 ms  
 17  [  128.119.3.153]  128.119.3.153  92 ms  
 18  [ 128.119.245.12]  gaia.cs.umass.edu  89 ms  

--- traceroute statistics for gaia.cs.umass.edu
    18 packets transmitted, 17 received
    round-trip time (ms) min 8, avg 58, max 95
These are the answers:
  1. The IP address of my PC is 67.182.228.87
  2. Protocol: ICMP (0x01)
    1. 20 bytes
    2. there are 50 bytes
    3. It is (packetLength - wrapperLength)
      i.e. 70 - 20 = 50
  4. No both the flags and the fragment offset are at zero
  5. The Identifier and the Header Checksum change in every frame
    1. Fields that stay constant are: Header Length, Type of Service, Datagram Length, Flags, Source Address, etc.
    2. Must stay constant: Header Length, Datagram Length, Source Address, Dest Address, etc.
    3. Must change: TTL, Identifier, Header Checksum, etc.
    4. TTL because it's in the tracert's nature
      Identifier because it's a counter
      Header Checksum because it's different for every frame
  7. It's just a counter, no pattern identifiable
  8. Identification field = 0xef09 and TTL = 254
  9. No. Identification must change
  10. Yes packets are fragmented