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Decision Support Systems Used In Network Hardware

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Decision Support Systems Used in Network Hardware

How does data pass through the internet? If you said decision support systems, you are correct. In an indecisive world, network hardware devices uses decision support systems (DSS) to efficiently and effectively route data, in a local area network, with the least amount of errors and inconsistencies. Decision support systems are the brains behind network hardware, and would be near impossible for them to work without the intelligent core of each distinct DSS. There are a variety of network hardware devices: switches, hubs, and routers; and they all use algorithms/procedures to transfer data towards the correct destination. Although there are many more DSS related methods used to route traffic, this paper describes how these three devices use them and each of there functions. Other types of decision support systems that network hardware devices may use are firewall technology, network address translation, and filter tables, which are all described in this paper.

Network hardware is used in the first three layers of the OSI reference model. The OSI reference model is the Open Systems Interconnections standard and consists of seven layers that build from the wire. At the first layer, "the physical layer", hubs maybe used for simple, inexpensive technology within a corporation. Hubs, when receiving data sent to it, sends that data too all network interface cards, or NICS on each computer. If the data is at its correct destination, the NIC to read the data, but if it is not, the data is discarded. Of course, this setting is much slower, because the other NICS are waiting for there turn, which is after the first message is delivered or timed out. Raymond R. Panko writes this about the waiting state a hub goes in when transmitting data: "This creates latency (delay), which grows as the number of stations grows. Another way of saying this is that the speed of the hub is shared. (Panko 108)" As, you can tell, hubs are simple, and don't use more information than needed.

Switches, which are layer 2 devices, use decision based routing by storing NIC hardware addresses and port numbers on a table in the switch. By doing this, when data is received by the switch, it knows where the source was, and where the data needs to go. This allows for faster data transmission for all NICS that are connected, because it uses the switches full bandwidth and there is no broadcasting across ports. Panko writes this about switches: "This approach allows multiple conversations to take place at the same time...There is no need to wait while another station is transmitting. (109)"

Whereas switches and hubs are used within single networks, routers are used to connect two or more networks together into an internet. Roozbeh Razavi of writes: "Routers use routing algorithms to find the best route to a destination. When we say "best route," we consider parameters like the number of hops (the trip a packet takes from one router or intermediate point to another in the network), time delay and communication cost of packet transmission. (How Routing Algorithms Work 2nd pg. par 1)" More data is collected in a routing table on routers than there is on switches. For instance, a routing table on a router includes these attributes: Row #, Network/subnet, Mask (/prefix), Metric (cost), Interface, and Next-Hop Router. Each row on the table accounts for a device connected to the router, and the last row on the table accounts for the broadcast channel for all devices. The network/subnet column of the table tells the router the address of another network connected to the router. The mask column is used by the router to calculate the network part of the network address, and the subnet part of the network address. The metric, or cost is the number or time it takes to reach a specific destination. The interface is the outgoing port on the router, and last but not least is the next-hop router, which tells the router the address of the next existing router that it is connected to. Michael J. Norton, a software engineer at Cisco Systems describes the next hop a little cleaner:

Routers maintain information about other routers in the network. A router that is on the same network segment as another router is said to be a routing neighbor. A distance metric is assigned to the neighbor router. This distance metric is called a hop. Neighboring routers are said to be one hop away from the local router (Norton par 11).

To learn how a router knows where to send a packet of information, this detailed description describes these processes:

The routing system selects an entry from the routing table and takes the netmask from that entry. The system then performs a logical AND of this value and the destination address. The resulting value is compared to the network address in the table entry. If the two values are the same then the destination can be reached through the gateway in that entry. If the two values are different then the routing system moves to the next entry in the table. If the table is exhausted and no matching entry is found, then the usual result is for the routing system to discard the packet and generate a message notifying the sending application that the destination network is unreachable. (Whipple par 1)

Routers, compared to the other two devices mentioned, hold more information about connections for the router to easily process requests. Of course, this makes routers more expensive, increasing in price as the number of connections increases. The price of this technology is dropping rapidly, as more and more people are switching to wireless routers and NICS. Soon, switches and hubs will be replaced by more intelligent routers which do not even use physical lines, just radio frequencies, making local area network access easier to setup and to connect too. Maybe someday, more attributes or columns will be added to the table, hoping to increase speed and intelligence. For now, these routers with routing tables located on them are the way to go, because they work, and they work intelligently fast.

Another form of decision support systems used by a router maybe a firewall, which protects a network from nonallowed messages from the outside. Jeff Tyson of writes this about firewalls: "Basically, a firewall is a barrier to keep destructive forces away from your property. In fact, that's why its called a firewall. Its job is similar to a physical firewall that keeps a fire from spreading from one area to the next" (How Firewalls Work par 3). Firewalls work wonders for companies that only want certain incoming data to be processed. The router itself either rejects or accepts an incoming message based on



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