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HW02review

Homework #5 connection-oriented vs connectionless

• connection-oriented networks
  • all bandwidth on the circuit only for just that conversation (even silence)
  • hard guarantees
• connectionless networks
  • shared resources, optimal utilization
    • Tragedy of the Commons and common pool resource
    • On The Self-Similar Nature of Ethernet Traffic
      • bursty, fractal
    • Measured Capacity of an Ethernet: Ethernet ain't as bad as you think!
  • best effort
• which one is better? it's "religious"
  • Netheads vs Bellheads

Homework #6 hub vs switch

• hub
  • shared medium divides the available bandwidth, does not scale
• switch
  • switched medium optimizes bandwidth use, theoretically multiplies bandwidth, scales well
  • each port is its own collision domain (no CRC errors, runts, or jabbers expected)

Homework #7 7-Layer Model

• wikipedia
• review
• Religious, Political, Financial (humor)

Homework #8 IP drill

• my IP in dotted decimal 152.2.145.34
• my IP in dotted hex 0x 98.02.91.22
  • you can use Google or an online converter
• my default router (gateway) is 152.2.145.1
• my netmask is 255.255.0.0
  • in binary: 11111111.11111111.0.0
    • my previous netmask was 255.224.0.0; that's 11111111.11100000.0.0
  • With the 255.255.0.0 netmask (classic Class B network), there are 16 bits for the network portion (255.255) and 16 bits for the host portion (.0.0). So you could have 2¹⁶ hosts, less 2 (one to represent "this network" and one for "all stations / broadcast"), less 1 (me!), or 65,533 hosts could be local to me.
    • The 255.224.0.0 netmask has 11 network bits (count the ones in binary) and 21 hosts bits (count the zeroes in binary), so 2²¹ - 3 is 2,097,149 potential neighbors
  • potential neighbors on my LAN range from 152.2.0.1 low to 152.2.255.254 high
    • with the 255.224.0.0 netmask, potential neighbors (hosts) range from 152.0.0.1 to 152.31.255.254
      • 10011000.00000010.10010001.00100010 masked with
      • 11111111.11100000.00000000.00000000
      • 10011000.00000000.00000000.00000000 (this network)
      • 152.0.0.0 (this network, but unclear notation) or the 152.0.0.0/11 network
      • 10011000.00000010.10010001.00100010 masked with
      • 11111111.11100000.00000000.00000000
      • 10011000.00011111.11111111.11111111 (broadcast)
      • 152.31.255.255 (broadcast on the 152.0.0.0/11 network)
    • Online IP CIDR Supernet Calculator
  • note, my netmask could be smaller while leaving my default router local (as required); it could be 255.255.255.0; but my default router used to be 152.2.192.1 (and I still use that one on occasion) and before that it was 152.2.254.254 (and that still works too) so I leave it big
• arp entries