Ever-increasing network speeds and the construction of applications to exploit them are driving network administrators to meet the needs of a much more demanding research community. Researchers on campus and in labs have increasing expectations of network performance as applications become more sensitive and dependent on consistent, high-quality network performance.
CIOs and the networks they administrate find themselves poised to benefit from the implementation of extensive measurement tools. A number of drivers both inside and outside our institutions are moving our campuses toward implementing this infrastructure. They include:
- Increasing requirements for interdisciplinary and inter-institutional research and collaboration. Academic collaboration requires appropriate sharing of data and resources among institutions. Scientific communities must be able to communicate quickly and reliably over long distances. Massive amounts of data are sent between sites on a regular basis. Video conferencing and other distance learning tools would also benefit greatly from monitored network performance.
- Changing needs of researchers. As mentioned above, researchers today rely on applications that push technology to the limit. Extremely high-speed networks are a necessity to support the applications in use today. Basic network infrastructure must not be responsible for holding back research.
- Escalating expectations for 24-7 access to and use of optimally performing technology. On one hand, many users of high-speed applications have become used to below-optimal performance. However, as new applications are developed and objectives are created there is a need to proactively change user expectations and improve the image of the network.
- Increasing budgetary pressures. Networks must be effective and performing well to be cost-effective. Why rewire the network or install optical fiber if the end-to-end performance does not reflect that investment. Make sure that your investments provide all the return they can and earn you the recognition you deserve.
Often the best way to describe or illustrate the recommended uses of a given technology is through the use of case studies. Following is a list and related descriptions of types of specific performance monitoring applications known to be in production at other locations at the time of writing this document. The tools employed and technical terms are explained more fully in the Glossary. Application descriptions have been grouped into broad application categories to help the reader understand their role in an overall IT infrastructure.
Real time point-to-point data transfer
Tuning a path in preparation for a real time point-to-point data transfer is accomplished by testing multiple points along a network path to determine the network characteristics. Doing so requires direct contact with the network or system administrators who control the hosts along the path to conduct Iperf tests. These tests consume a great deal of bandwidth and administrators are, rightfully, wary of allowing others to perform such tests on their networks. If servers along the path have installed BWCTL, testers can schedule Iperf tests remotely, without contacting the administrator because BWCTL encapsulates the Iperf test, rendering it harmless to the server. As a result, the tester has the results he needs regarding performance and the network administrator does not have to worry about the bandwidth requirements of the test or grant privileges to individuals he or she may not know. In addition, should a problem be noted, the tester now has data to back-up his or her claim of non-performance and the administrator of the node in question has resources to support his troubleshooting.
While developers and users of applications would like the network to run perfectly – with high speed and zero-loss – network engineers recognize that the network will never run absolutely perfectly. But, until applications are developed to be more robust and able to withstand common network errors, network administrators and engineers will need to be able to tweak networks to deliver near-zero packet loss. Speed is not the only component to performance that can be of concern. Packet-loss can often be more devastating than slow traffic on the network. Using, and reporting, regularly to network “weather maps” can help network administrators diagnose problems on their own campus as well as point to problems along the path of interest in other domains.
High volume, regular data transfers
Occasionally, a user will experience a sudden drop in network performance while performing routine data transfers. When end-users are familiar with performance on their systems and have a good understanding of their network topology they are better prepared to address sudden changes in network performance. Having a set of network tools available to users will help define and isolate the problem. When such a problem occurs, immediately talking to network staff about upgrades or modifications to the path you are on will go a long way towards quickly resolving the problem. Simple switch and router configurations can have unforeseen consequences, especially in regards to performance and network administrators will not know of the direct impact unless end-users can inform them and back up their claims with data.
Using cakeboxes, or small, inexpensive PCs configured to register its presence with on a network so you can “find it”, network engineers can test H.323 video conferencing and other network application capabilities. Using the cakeboxes an engineer can locate where packet loss in a transmission may be occurring. The tests can be directionalized so that problems can be isolated to particular venues or areas of the network. Sometimes these problems are as simple as a duplex mismatch but without tools to help identify the location of the problem the resolution becomes much more difficult. Other diagnostic tools, such as the Network Diagnostic Tool (NDT), allow users to perform limited diagnoses from their desktop. These easy to install and inexpensive tools quickly eliminate specific paths as possible problems and can help point to the true culprit.