In the first few installments of this series on network troubleshooting solutions, we highlighted three tools that administrators can use to glean insight about network performance: the packet analyzer, the command level interface (CLI), and the Simple Network Management Protocol (SNMP).
These solutions are all similar in that they provide useful feedback related to device performance and packet flow. But they don’t provide much insight into end user activity, which can so often be the cause of slow speeds and communications issues. For this information, network professionals often turn to a tool called a traffic monitor.
What it is: A traffic monitor—like NetFlow and its brethren SFlow and JFlow— is a network protocol used to map network bandwidth usage. Network professionals use traffic monitors to identify slowdowns due to bandwidth constraints.
What it’s useful for: NetFlow, SFlow and JFlow are all powerful technologies which can be used to report who specifically used a network at a given point in time. For example, users may complain that a network is slow at the same time every day. Network administrators can use a traffic monitor to peek into the specified time and identify where the traffic is coming from on the network (i.e., a standing VoIP call or online meeting).
What it’s bad for: Traffic monitors are becoming less valuable as companies are migrating to faster wide area network (WAN) technologies and are dumping their 1.5 Mbps T1 circuits in the process. These new networks typically have 10 meg and 100 meg metro-Ethernet and MPLS WAN connections to remote offices and are typically not as congested as the old point-to-point T1 and frame-relay circuits of old. What’s more, solutions like NetFlow are incapable of identifying issues like packet loss, latency and jitter. It will simply point to who was using the network at a specific point in time.
Conversely, a real-time network troubleshooting solution like PathSolutions TotalView will allow you to see not only how bandwidth is being allocated across the network, but also why bottlenecking is occurring.
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