Most large companies have established computer networks. Few companies would willingly throw out their existing computer network to create a new computer network. Instead, they typically add new technology, such as wireless LAN (WLAN), to existing networks, where it makes sense. Smaller companies and new companies, however, often face the prospect of designing and implementing a new computer network from the ground up. This is sometimes called a Greenfield installation.
The first step is to do a high-level network design. The company may use an internal network architect or hire an outside consultant for this purpose. The network architect chooses the network topology, network protocol, and network architecture best suited to the network users' needs. The network architecture must also provide for fault tolerance and redundancy (via clustering, mirroring or other techniques), so no data will be lost in the event of a network failure.
After the completion of design, the company would purchase and install the hardware and software contained in the network design. The task of managing the network then falls to the network administrator or administrators, who are charged with ensuring the network is available, performs well, and is secure from unauthorized users (whether inside or outside the organization). Network administrators use a variety of network management software and tools to do their jobs.
A network monitoring application is one form of network management software. This software "watches" network traffic, compares it with various measures of network health, and warns if the network is about to go down. If one network circuit is becoming overloaded, for example, the network monitoring software would automatically send an alert (such as an email or page) to the network administrator, who would then take action. Most network monitoring tools present consolidated information on a console resembling the cockpit of an airplane so the network administrator can judge at a glance how the network is faring. Remote network management software gives the network administrator remote access to the network management tool so he can see how things are going - from home, for example - and even fix problems that arise.
Network performance management software reports on network quality of service (QoS) metrics such as sub-standard application performance and conformance with applicable service level agreements. This type of tool analyzes past network performance and proactively suggests ways to avoid problems in the future.
Network security is of increasing importance given the burgeoning number of attacks on computer data, including viruses and worms. Many companies have a separate computer security department or designate one network administrator to focus on security. The network security specialist uses an arsenal of software tools to help protect network data. For example, intrusion detection systems sit on the network perimeter and analyze traffic patterns for signs of attack. These widely deployed systems often result in more paper printouts than the security person could possibly hope to absorb. Intrusion prevention systems are a newer addition. While intrusion detection points out possible attacks after they have occurred, intrusion prevention technology attempts to identify unwanted types of traffic and preventing them from getting on the network in the first place.
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