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									Future Academy
Networks
3rd year
Computer Sciences
Spring Semester 2009
Exercise (8) see text book
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Question (1)**page 23
Construct a comparison table to classify the computer networks based on:
      scale
      connection method
      functional relationship (Network Architectures)
      network topology
      protocol
By scale (size)
Computer networks may be classified according to the scale: Personal
area network (PAN), Local Area Network (LAN), Campus Area Network
(CAN), Metropolitan area network (MAN), or Wide area network (WAN).
As Ethernet increasingly is the standard interface to networks, these
distinctions are more important to the network administrator than the
end user. Network administrators may have to tune the network, based
on delay that derives from distance, to achieve the desired Quality of
Service (QoS). The primary difference in the networks is the size.
Controller Area Networks are a special niche, as in control of a vehicle's
engine, a boat's electronics, or a set of factory robots.

By connection method (ethernet or wireless)
Computer networks can also be classified according to the hardware
technology that is used to connect the individual devices in the network
such as Optical fiber, Ethernet, Wireless LAN, HomePNA, or Power line
communication.
Ethernets use physical wiring to connect devices. Often, they employ
the use of hubs, switches, bridges, and routers.
Wireless LAN technology is built to connect devices without wiring.
These devices use a radio frequency to connect.

By functional relationship (Network Architectures, capabilities)
Computer networks may be classified according to the functional
relationships which exist between the elements of the network, e.g.,
Active Networking, Client-server and Peer-to-peer (workgroup)
architectures.

By network topology
Computer networks may be classified according to the network
topology upon which the network is based, such as Bus network, Star
network, Ring network, Mesh network, Star-bus network, Tree or
Hierarchical topology network, etc.
Network Topology signifies the way in which intelligent devices in the
network see their logical relations to one another. The use of the term
"logical" here is significant. That is, network topology is independent of
the "physical" layout of the network. Even if networked computers are
physically placed in a linear arrangement, if they are connected via a
hub, the network has a Star topology, rather than a Bus Topology. In
this regard the visual and operational characteristics of a network are
distinct; the logical network topology is not necessarily the same as the
physical layout.

By protocol
Computer networks may be classified according to the communications
protocol that is being used on the network. See foundations protocol
stacks.

Question (2)** page 30
Fill out the following table
Abbreviation       Details            examples            illustrations        Comments
PAN
LAN
CAN
MAN
WAN
GAN

http://en.wikipedia.org/wiki/Computer_network

http://ar.wikipedia.org/wiki/%D8%B4%D8%A8%D9%83%D8%A7%D8%AA_%
D8%A7%D9%84%D8%AD%D8%A7%D8%B3%D9%88%D8%A8

          ‫فى االول خالص ادخل على اللينكات و اقرا انواع الشبكات و افهم كل واحده قبل ما تملى الجدول‬


Question (3)** page 35
Discuss the Egypt's ethernet in terms of Scalability, Resiliency, Multiprotocol
convergence, and End to End OAM

Scalability: pure Ethernet MAN are limited to a maximum of 4,096 VLANs
for the whole network, when using MPLS, Ethernet VLANs have local
meaning only (like Frame Relay PVC). Same scalability considerations
applies to the MAC addresses where in a pure Ethernet MAN all MAC
addresses are being shared among the network while only having local
meaning in the MPLS context.
Resiliency: pure Ethernet network resiliency relies on STP or RSTP (30
to 1 sec convergence) while MPLS-based MANs use MPLS-based
mechanism (i.e. MPLS Fast Reroute) to achieve SDH-like (50 msecs)
convergence times.
Multiprotocol convergence: with the maturity on pseudowires standards
(ATM VLL, FR VLL, etc.) an MPLS-based Metro Ethernet can backhaul
not only IP/Ethernet traffic but virtually any type of traffic coming from
customers networks or other access networks (i.e. ATM aggregation for
UMTS).
End to End OAM: MPLS-based MAN offers a wider set of
troubleshooting and OAM MPLS-based tools which enrich Service
Providers ability to effectively troubleshoot and diagnose network
problems.

Question (4)** page 40

          I have a good amount of information                   I have a good amount of information too
          I am ready to exchange mine                           I am ready to exchange mine too




The concept of P2P is increasingly evolving to an expanded usage as the
relational dynamic active system in distributed networks. Discuss the P2P
networks in terms of
    Classifications                           Computer science perspective
    Advantages                                Application outside Computer Science
    Unstructured and structured               Attacks
    Legal controversy                         Security



P2P networks can be classified by what they can be used for:

        file sharing
        telephony
        media streaming (audio, video)
        discussion forums

Advantages of P2P networks

An important goal in P2P networks is that all clients provide resources,
including bandwidth, storage space, and computing power. Thus, as
nodes arrive and demand on the system increases, the total capacity of
the system also increases. This is not true of a client-server architecture
with a fixed set of servers, in which adding more clients could mean
slower data transfer for all users

Unstructured and structured P2P networks

The P2P overlay network consists of all the participating peers as
network nodes. There are links between any two nodes that know each
other: i.e. if a participating peer knows the location of another peer in
the P2P network, then there is a directed edge from the former node to
the latter in the overlay network. Based on how the nodes in the overlay
network are linked to each other, we can classify the P2P networks as
unstructured or structured.
Computer science perspective

Technically, a completely pure P2P application must implement only
peering protocols that do not recognize the concepts of "server" and
"client". Such pure peer applications and networks are rare. Most
networks and applications described as P2P actually contain or rely on
some non-peer elements, such as DNS. Also, real world applications
often use multiple protocols and act as client, server, and peer
simultaneously, or over time. Completely decentralized networks of
peers have been in use for many years: two examples are Usenet (1979)
and WWIVnet (1987).

Application of P2P network besides file sharing

      Bioinformatics: P2P networks have also begun to attract attention
       from scientists in other disciplines, especially those that deal with
       large datasets such as bioinformatics. P2P networks can be used
       to run large programs designed to carry out tests to identify drug
       candidates. The first such program was begun in 2001 the Centre
       for Computational Drug Discovery at Oxford University in
       cooperation with the National Foundation for Cancer Research.
       There are now several similar programs running under the
       auspices of the United Devices Cancer Research Project.

Security

Some P2P protocols (such as Freenet) attempt to hide the identity of
network users by passing all traffic through intermediate nodes.

								
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