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Slow Network, Slow Application or Slow Server?

One of the biggest gripes heard by company network administrators is that the network is slow. In February, we provided tips for determining whether the network or the application was to blame for latency. IT folks have engaged and continue to engage in the debate around what is to blame for slow performance – the application, the server, or the network? This “blame game” has gone so far as to create real animosity in some organizations among developers, sys admins, network administrators, and end users. True story – the WildPackets professional services team occasionally is summoned by customers to do nothing more than settle these arguments.

While the answer to the question “What is to blame for slow network performance?” obviously depends on a case-by-case basis, we can provide with certainty four reasons for a slow network:

1. Overall network utilization

Network utilization is the ratio of current network traffic to the maximum traffic that the port can handle. When network utilization exceeds the ceiling under normal conditions, the result will be low transmission speeds, intermittence, and request delays — in other words, a slow network. High network utilization can stem from a number of sources, but some obvious culprits caused by end users include music, video downloads and video streaming.

2. Devices on the network consuming a considerable amount of bandwidth

Almost every network has unnecessary traffic. Some devices (especially printers) support stacks and protocols that aren’t in use in the environment. Often, WLAN traffic has not been pruned. Sometimes, protocols that help manage the network, like routing protocols, SNMP, etc., can be found on those WLANs without any purpose, eating up available bandwidth, again, with no benefit.

3. Overall health of the network (in terms of broadcast storms)

Since the network is dynamic, it is critical that organizations consistently review network activity. Businesses should verify that the processes and/or devices architected are accomplishing what they need to and that the overall network profile has not changed. It is very important to see new trends approaching and make changes to the network to account for behavioral changes in an organization’s user communities. If not, organizations could unknowingly become victims of broadcast storms where the network is overwhelmed with constant broadcast or multicast traffic that can lead to a complete loss of network connectivity as the packets proliferate.

4. Particular ports or new applications that have been introduced to the network

Every organization will have different priorities. In fact, each network segment may have different protocol priorities because of the specific applications that traverse those segments. Certainly, the top application (based on business importance) on the sales segment will be different from the top application on the marketing segment. Those application protocols need to be handled in terms of importance on each segment. But, when those protocols get to the same wire at the core or elsewhere, it is important that they still respect other segments’ needs. After all, applications are the primary reason organizations invest in networks.

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