Homework2

v  Layering (in network design) provides two nice features, explain how ?

 * Decomposes the problem of building a network into more manageable components .

*It provides a more modular design.

v  Define the following terms :

http: The underlying protocol used by the World Wide Web.

URL: the address of a specific Web site or file on the Internet.

link: Some physical medium, such as a coaxial cable or an optical fiber.

node: (connection point) refer to the computers it connects.

packet: Blocks of data as corresponding to some piece of application data such as a file , apiece of email.

Store-and-forward: Packet-switched networks typically use a strategy.

Switched: Store and forward packets.

hosts: Network nodes which use the network.

Router: A node that is connected to two or more networks.

Routing: The process of determining systematically how to forward messages toward the destination node based on its address.

Node address: An identifies a specific computer or terminal in a group of interconnected computers on a network.

Multiplexing: A system resource is shared among multiple users.

Congestion: A switch receive packets faster than it can send them for an extended period of time, then the switch will eventually run out of buffer space, and some packets will have to be dropped, when a switch is operating in this state.

Bit error: A 1 is turned into a 0 or vice versa.

OSL: a standard description or "reference model" for how messages should be transmitted between any two points in a telecommunication network.

TCP/IP:is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet. (
Architecture: A blueprints that guide the design and implementation of network.

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.