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At the high end of wireless services are satellite, laser, and microwave. These solutions frequently connect entire networks and require the involvement of the network designer.
Satellite services are typically deployed to address two possible needs. The first involves the availability of cable-based installationsmany countries are cursed with the theft of copper cables. Stories are rampant about circuits that have mysteriously failed. Upon dispatch, the vendors have learned that miles of copper cable have been cut and removed from the poles.
The second satellite installation usually involves mobile stations, including ships. These networks link shipboard computers with monitoring stations that use real-time data to schedule maintenance and provide communications. While the biggest negative to satellite communications is cost, the designer should also consider link delay.
Laser and microwave installations are excellent short-range solutions. Each avoids the need to trench or pull cable in order to connect two networks, and the reliability of these solutions has increased substantially.
Designers should consider reliability and distance when evaluating these options. The cost savings can be substantial, as there is only a one-time charge for the initial hardware purchase and there are no ongoing leased-line fees to pay.
Advances in wireless technology will likely improve wireless coverage and reduce the costs of these solutions.
Most network managers and directors will point to documentation of the network as a key concern and trouble area. Another concern is case management.
Case management is a concept similar to trouble-ticket tracking, but it incorporates a broader scope. Many companies use trouble tickets to record problems called into the help desk or service center. Trouble-ticket tracking is the act of reviewing these tickets to improve customer service. Cisco provides an excellent example of case management that starts with the Cisco Connection Online Web site (CCO), located at www.cisco.com. Customers may reference trouble tickets and manually locate patch files and software images without the intervention of the TAC, or Ciscos technical assistance center. Should the customer find it necessary to speak to a staff member for problem resolution, the Web-based trouble ticket can automatically generate the request.
It is important to note that case management is more than just a ticket-tracking system. It is a philosophy that must incorporate ownership of the problems and, as Cisco has proven, admission of problems to customers in a timely fashion. Few other companies have been as brave in documenting their bugs and other problems as Ciscofew have been as successful in resolving them as well. In addition, Cisco surveys every customer and expects each technician to earn the highest satisfaction scores on every case. This acceptance of nothing less than the best has earned the company numerous distinctions.
Network design can augment the case-management process. As noted in Chapter 7, the use of naming conventions can greatly simplify the troubleshooting process. By linking machine names, IP addresses, and other network information to the ticketing system, a single call could generate a note to all other call takers (and ultimately an automated system) that documents the possibility of a larger failure. This can easily shorten the diagnostic process since administrators are focused on a single problem instead of looking at each call as an isolated issue.
Many organizations are also providing real-time network data to end users, or at least small groups of end users. This preemptive measure can greatly reduce the number of calls reporting a network capacity problem (described in the next section) because the user can see that a link is operating at only five percentthus showing that the problem is likely not caused by excessive utilization. While this does not exonerate the network, it does squelch the call to immediately upgrade the circuit. By providing this information, the designers and architect can initiate a stronger dialog with their users.
I was recently asked during an interview how I do trend analysis and capacity planning. I answered respectfully that I could provide two answersthe textbook response or the real-world truth. I passed over the question without further comment and accepted the position.
The sad truth is that many organizations havent the time or expertise to perform an accurate analysis of their network resources. Numerous products, including CiscoWorks and Concord Network Health, can greatly simplify the data-collection process, but at some point the designer needs to understand the specific utilization on a circuit in order to determine if additional capacity is warranted.
You may wonder what could possibly be analyzed when the circuit is running at 100 percent capacity. However, as an architect, you need to under-stand why traffic rates are so high and to ascertain if this growth was part of the original analysis. Frequently, designers will learn with research that a 256Kbps circuit is supporting unnecessary Web browsing or another optional traffic flowsometime these unnecessary data flows can consume 75 percent or more of a circuit.
|While each organization is different, the last three audits performed by my team (for two different organizations) showed that over 80 percent of the utilization was for stock quotes, sports scores, and other non-business-related material on the circuit. Each company must define acceptable business use, but when utilization is unrelated to the business, it becomes difficult to ignore the associated expense.|
Designers must become increasingly vigilant for the bandwidth trapthe addition of more and more bandwidth. This consideration will become increasingly important as the associated costs increase. Increasing costs are due to the fundamental limitations of WAN technologyhigh recurring costs and high latency (compared to local data stores and cached data). Of course, some organizations, including the government and the sciences, must transfer huge amounts of data daily. Business also may need to send large databases and other files, but compression and other techniques may provide a solution. Recently, a number of financial institutions audited their Web sites and reduced the size of their graphics files to accommodate their customers. Users of low-speed links immediately appreciated the effort, and little content was lost. Most important, however, the change extended the length of time that the current bandwidth capacity will continue to meet their needs. Historically, bandwidth demands have required a doubling of capacity every 6 to 12 months in this market.
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