الاثنين، 17 سبتمبر 2012

Homework 1

 - Explain why connectivity is a major network requirement and explain how is it possible for different  hosts to be sharing the same link ?
Because a network must provide connectivity a set of computer.
More than 2 nodes may share a single physical link a (multiple access).


 
- Explain why is meant by a switched network, and write about: packet -switched vs circuit -switched ?

Switched network : data received on one link is for worded on the other one .

*Packet-switched :
  •  The important feature of packet-switched networks is that the nodes in such a network send discrete blocks of data to each other.
  • These blocks of data as corresponding to some piece of application data such as a file, a piece of email, or an image.
  • We call each block of data either a packet or a message.
  • Packet-switched networks typically use a strategy called (store-and-forward).                                
 *Circuit-switched :
  • Establishes a dedicated circuit across a sequence of links and then allows the source node to send a stream of bits across this circuit to a destination node.
  • The major reason for using packet switching rather than circuit switcging in a computer network is etficiency.


    - What are the two key challenges of statistical multiplexing ?

    • Like STDM in that the physical link is shared over time.
    • Unlike STDM, data is transmitted from each flow on demand rather that during a predetermined time slot.

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