Ever wonder how the ancient merchants like Marco Polo figured out the best routes to travel around the world? Well, I don’t. But I do wonder how to get my data across the globe in the quickest way possible, and the routing tools in Network Performance Monitor (NPM) can help you do that.
There are five resources found in NPM 10.5 and later, that can help you troubleshoot routing issues to get your network back on track and optimized for maximum performance.
- Routing Table
- Top 10 Flapping Routes
- Routing Neighbors
- Default Route Changes
- Routing Details
Note: The easiest way to see all of the Routing Resources together by default, is to click the "Network" sub-view on a Router’s Node Details page.
The table below describes each of the aforementioned routing resources, providing a basic understanding of the feature set.
Each Router has its own Routing Table and each Routing Table is potentially different for any given router in your network. As you can see the Routing Table information is displayed across 6 columns:
• Destination Network - a list of networks you can reach from the Router you are on.
• CIDR - The Classless Inter-Domain Routing for the given Destination Network.
• Next Hop – The next router, or “next hop”, you need to go through to get to the given Destination Network.
• Interface – The actual interface on the Next Hop router that the packets are sent through.
• Metric – Routing Tables only keeps the best routes available and each protocol has its own of set metrics used to determine what the best route is. In general the lower the number the faster the route.
• Source – The Source column shows the protocol being used.
Top 10 Flapping Routes
The term “flapping” refers to a condition where a Router advertises a destination network via a particular route and then quickly sends another advertisement for a different route. When interfaces on a router go up and down unexpectedly or more frequently than they should, this causes a recalculation of routes in your Routing Tables. This actually slows down routing, and the slow network speed may result in outages or other connectivity issues.
The Top 10 Flapping Routes resource shares some columns in common with the Routing Table, so we will just focus on what is different and unique here:
The Routing Neighbors resource shows you which routers are directly connected to the router you are currently viewing and it provides status on this relationship. This table can be useful in the case where neighboring routers might be down or display other issues that might hinder the ability to route packets through your network.
The Routing Neighbors resources shows several more columns of information useful for troubleshooting:
Default Route Changes
The Default Route Changes resource provides a quick view of any changes made to default routes and help you narrow down when changes have occurred and help you correlate with other known data to help with your troubleshooting. You can set the view from the last 24 hours, the last 3 days, last 7 days, last 14 days and the last month.
|The Routing Details resource provides you a quick glance at when Protocols were last polled so you will know how fresh your routing data is. Special note, the row which says “Routing Table poller” is just showing you when the routing table was last polled by NPM for this device.|
Customer feedback for the new Routing Tools in Network Performance Monitor has been overwhelmingly positive and the tools are doing a great job at what they are designed to do, speed up troubleshooting of routing issues and make your work life much easier!
In my upcoming blog post we will walk through some troubleshooting scenarios using the Interactive Online Demo to give you a better sense of how to actually use the routing tools.