NetWork

Basic Network Topology

1. STAR TOPOLOGY

2. RING TOPOLOGY

3. BUS TOPOLOGY

1.Explain the cirumstances under which a token-ring netwrok is more effective than an Ethernet network.

A Token Ring network is a local area network (LAN) in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time. The Token Ring protocol is the second most widely-used protocol on local area networks after Ethernet. The IBM Token Ring protocol led to a standard version, specified as IEEE 802.5. Both protocols are used and are very similar. The IEEE 802.5 Token Ring technology provides for data transfer rates of either 4 or 16 megabits per second. Very briefly, here is how it works:
1. Empty information frames are continuously circulated on the ring.
2. When a computer has a message to send, it inserts a token in an empty frame (this may consist of simply changing a 0 to a 1 in the token bit part of the frame) and inserts a message and a destination identifier in the frame.
3. The frame is then examined by each successive workstation. If the workstation sees that it is the destination for the message, it copies the message from the frame and changes the token back to 0.

4. When the frame gets back to the originator, it sees that the token has been changed to 0 and that the message has been copied and received. It removes the message from the frame.
5. The frame continues to circulate as an "empty" frame, ready to be taken by a workstation when it has a message to send.
The token scheme can also be used with bus topology LANs.
The standard for the Token Ring protocol is Institute of Electrical and Electronics Engineers ( 802.5. The Fiber Distributed-Data Interface (FDDI) also uses a Token Ring protocol.

Ethernet network is a standard communications protocol embedded in software and hardware devices, intended for building a local area network (LAN). Ethernet was designed by Bob Metcalfe in 1973, and through the efforts of Digital, Intel and Xerox (for which Metcalfe worked), "DIX" Ethernet became the standard model for LANs worldwide.

1. A basic hard-wired LAN consists of the following components:

2. Two or more computers to be linked together, or networked.
3. A network interface card (NIC) in each computer
Ethernet cable to connect to each computer.
4. A networking switch or networking hub to direct network traffic.
Networking software.

2. Although security issues were not mentioned in this chapter, every network owner must consider them. Knowing that open networks all data to pass to every node, describe the posssible security concerns of open network achitectures. include the implicatiions of passing logon procedures, user IDs, and passwords openly on the network.

In telecommunications, and in the context of Federal Communications Commission's (FCC) Computer Inquiry III, Open network architecture (ONA) is the overall design of a communication carrier's basic network facilities and services to permit all users of the basic network to interconnect to specific basic network functions and interfaces on an unbundled, equal-access basis.

The debate has raged for years. … Now seeing that people in security using open source are running across the same issue. One side of the argument says that closing the source is more secure because it's hiding how you are securing your network. The flip side of that argument is that open source has transparency, which translates into higher accountability. You actually can see how it is securing your network. [It shows] what the software is not doing, what it is doing, where the bugs are. That translates into accountability, and you want accountable. The other thing is that open source is a community. Proprietary software has a company behind it, open source has a community behind it. The software benefits greatly from the community

3.Remembering the discussion of deadlocks, if you were designing a networked system, how would you manage the treat of deadlocks in your network? Consider all of the following: prevention, detection, avoidance, and recovery.

the deadlock avoidance problem for the class of conjunctive / disjunctive (sequential) resource allocation systems (C/D-RAS), which allows for multiple resource acquisitions and flexible routings. First, a new siphon-based characterization for the liveness of Petri nets (PN's) modeling C/D-RAS is developed, and subsequently, this characterization facilitates the development of a polynomial-complexity deadlock avoidance policy (DAP) that is appropriate for the considered RAS class. The resulting policy is characterized as C/D-RUN, since the starting point for the policy development was motivated by the RUN DAP, originally developed for sequential RAS with unit resource allocations and no routing flexibility. The last part of the paper exploits the aforementioned siphonbased characterization of C/D-RAS liveness, in order to develop a su#ciency condition for C/D-RAS liveness that takes the convenient form of a Mixed Integer Programming (MIP) formulation. The availability of this MIP formulation subsequently allows the "automatic" correctness verification of any tentative C/D-RAS DAP for which the controlled system behavior remains in the class of PN's modeling C/D-RAS, and the e#ective flexibility enhancement of the aforementioned C/D-RUN DAP implementations. Finally, we notice that, in addition to extending and complementing the current theory on deadlock-free sequential resource allocation to the most powerful class of C/D-RAS, the presented results also (i) non-trivially generalize important concepts and techniques of ordinary PN structural analysis to the broader class of non-ordinary PN's, while (ii) from a practical standpoint, they can find direct application in the (work-)flow management of modern production, service and/or transportation environments.

4. Assuming you had sufficient funds to upgrade only one component for a system with which you are familiar, explain which component you would choose to upgrade to improve overall performance, and why?

If you have a new computer, then you will definitely need a Windows XP registry cleaner. I think the registry itself is not going to need fixing, if you don't ever do anything to your computer. But, once you start installing software, uninstalling software, making shortcuts on your desktop to your favorite programs, and even surfing the internet, you will need a good Windows XP registry cleaner. Let us cover the basics on what the registry files do, and why they are important. The registry files are the files, which tell the computer how a program is supposed to operate. It gives the basic instructions on what the program is suppose to do, and when it is suppose to do it. For comparison, they are like a recipe. With the recipe, and all ingredients, everything goes well. Without a recipe, you have no idea how to make something, or what order they go in. Even if you have all of the ingredients, you will still have a hard time cooking. It takes you much longer, if you even finish. Same goes for registry files. If these registry files are missing, or corrupted, the computer has a hard time doing what it is suppose to do. And, you will be amazed at how simple it really is mess up these files. If you install software, there is a change you will overwrite one of the registry files. So, now the file may work for the new program, and not the old program. Also, if you uninstall software, you can remove the registry file for another program. Now this program will not work....
Registry Repair: http://groups.google.com/group/regrepairsbv