Questions on Chapter 5

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Questions on Chapter 5

• Ying Zhang

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Question 1

• The efficiency of ALOHA
• When there are N active nodes the efficiency of
  slotted ALOHA is Np(1-p)N-1, find the value p
  that maximizes the expression
• Using the value of p found in (a), find the
  efficiency of slotted ALOHA by letting N approach
  infinity.

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solution
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Maximum efficiency of pure ALOHA

• Show that the maximum efficiency of pure ALOHA is
  1/(2e)

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solution
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Question2

• Consider a broadcast channel with N nodes and a
  transmission rate of R bps. Suppose the broadcast
  channel uses polling for multiple access. Suppose
  the amount of time from when a node completes
  transmission until the subsequent node is
  permitted to transmit(that is, the polling delay)
  is t_poll. Suppose that within a polling round, a
  given node is allowed to transmit at most Q
  bits. What is the maximum throughput of the
  broadcast channel?

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Question 3

• Consider three LANs interconnected by two routers
  below.
• A) redraw the diagram to include the adapters
• B) Assign IP addresses to all of the interfaces.
  For Subnet 1 use addresses of the form
  111.111.111.xxx for subnet 2 uses addresses of
  the form 122.222.222.xxx and for Subnet 3 use
  addresses of the form 133.133.133.xxx
• c) assign MAC addresses to all the adapters

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• D. consider sending an IP datagram from Host A to
  Host F. Suppose all of the ARP tables are up to
  date. Enumerate all the steps as done for the
  single router example

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subnet1
subnet3
router
router
subnet2
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