The performance of applications across the WAN are faced with many issues, such as latency, congestion, and low bandwidth. Your approach to determine how to troubleshoot the issues will vary based primarily on your budget.
For those on a limited budget, consider the following lost cost monitoring and troubleshooting options. If your network is slow then use the Netflow that comes embedded within the IOS of your router. Netflow can tell you things like the number and destination of packets coming from the interfaces of a router, as well its amount of packet load traffic. The statistics you collect will allow you to create a baseline for your network. It is from this baseline you can begin to learn when and where your bandwidth issues occur. Netflow is easy to setup and generally consists of a few lines of configuration to enable it. You can easily check to see if your Cisco devices support Netflow by going to here a performing a technology search.
Keep in mind that vendors use different types of flow technologies.
- Netflow- Cisco, Adtran
- Jflow – Juniper
- sFlow – HP, Foundry, Extreme. (sFlow is summarized, where as Netflow is detailed)
- IPFIX – next generation
If you are monitoring remote site performance then consider setting up Cisco IP SLA. Cisco IP SLA is also embedded in various routers and switches and can be enabled depending on the IOS. In fully meshed or Ethernet style networks, IP SLA will give you an understanding from a remote perspective. IP SLA statistics can be viewed from a command line or leveraged using a free tool. From the free SolarWinds IP SLA Monitor tool you can assign thresholds for up to five operation types. Define your warning and critical thresholds per operation and the tool will then go out to the router to perform queries. The results are pulled directly from the router of your operations and presented in a dashboard. With data from multiple operations, such as UDP echo, ICMP path echo (ping), TCP connect time, DNS resolution, and HTTP response, you can begin to troubleshoot your remote routers and prioritize bandwidth.
Another avenue to consider would be CBQOS. CBQoS (Class Based Quality of Service) is a Cisco feature set that is part of the IOS 12.4(4)T and above. This will provide data about the QoS policies applied and traffic patterns within your network. CBQoS can make network performance and bandwidth utilization more effective.
Use the network monitoring tools within your existing routers, such as Netflow, to monitor core CPU's , traffic over major links. Or a simple NetFlow analyzer tool can help you analyze the flow packets and monitor network traffic.
In the case of Cisco devices, use IPSLA, CBQOS, Netflow to help you monitor and troubleshoot network issues.