Future Academy Networks 3rd year Computer Sciences Spring Semester 2009 Exercise (8) see text book ----------------------------------------------------------------------------------------------------- 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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