How to Troubleshoot Network Issues with Traceroutes

Most network engineers will tell you when it comes to troubleshooting network problems, you don’t have to do it alone.

There are many tools on the market to help, from traceroutes to network monitoring software.

To make sure that you can properly leverage the tools available to you, it’s important to understand how they work and how to interpret the information they provide. 

Since 1987, traceroute has been one of the most popular tools that network engineers and IT specialists use to troubleshoot network problems.

Traceroutes are considered a most advanced tool, which many people don’t fully understand how to use and interpret. Keep reading to learn about Traceroutes and the role they play in monitoring network performance.

What Are Traceroutes?

First invented in 1987, Traceroutes are considered the most commonly used tool to troubleshoot network issues. Traceroutes are used in IP Networks to show the route path from a source to a destination. 

With traceroutes, users can see the different routers, or Hops, and the latency and packet loss between each of them. This can help you pinpoint where a network issue is located. Also, inside the traceroute, the Reverse DNS names of the routers can give a good idea of the service provider and the city for each of them.

Traceroute Complexities 

When it comes to troubleshooting with traceroutes, there are a few problems that people usually encounter with traditional traceroute tools.

1. When to Perform A Traceroute: Another issue that people encounter is not knowing when exactly to run a traceroute to catch current or past issues. When network problems occur, you’re not always behind your PC, ready to launch traceroutes. Sometimes, by the time you hear about the problem, the situation has changed and the problem has disappeared. So you need tools to help you catch problems as soon as they happen by launching automatic traceroutes and logging data before the problems disappear.

2. Traceroute from Both Directions: Internet traffic is asymmetrical, which is why you need a reverse traceroute, or traceroutes from both directions, to catch reverse-path issues. Most times, companies don’t have local IT resources that can perform traceroutes from both directions for them. By installing a network monitoring agent at your key business locations, you can perform traceroutes at a distance, in both directions. 

3. Having a Comparison Point: Traceroute is a powerful tool that helps pinpoint network issues. But how can you know that there’s been a change in your network performance if you have nothing to compare it to? That’s why you need historical data as a baseline to compare good performance and poor performance. 

4. Missing the Proper Knowledge: Many people simply don’t know enough about traceroutes to understand and interpret the results they provide to use when troubleshooting. That’s why it’s important to understand traceroutes by reading information like the Complete Guide to Traceroutes.

Find and Fix Network Issues with Traceroutes

When it comes to troubleshooting network issues, you can identify network issues with traceroutes by analyzing two metrics for each hop or router: latency and packet loss. 

Latency is the time difference between the time when a packet was sent and when a response was received. Packet loss refers to the percentage of sent packets that never received a response out of the total number of sent packets.

With a tool like Obkio Network Performance Monitoring Software, which offers an advanced traceroute feature, you can find and fix network issues faster than ever, while addressing the concerns I mentioned above.

Obkio Network Performance Monitoring software is a simple SaaS solution that allows users to continuously monitor the end-to-end performance of their network and core business applications to identify network issues, collect data on network performance, and improve the end-user experience.

Here are some key traceroute features that simplify network troubleshooting:

Live Traceroutes 

Live Traceroutes is a feature that shows the forward and the reverse traceroutes with latencies and packet loss in real-time. It’s a perfect tool to pinpoint the location of network performance issues, the minute they happen.

• Traceroute Sharing: People are used to sharing traceroute results by sending screenshots, which are essentially only a picture of the results. With a network performance monitoring solution like Obkio, you can launch a Live Traceroute and share your traceroute with other team members as well as with third-parties such as IT consultants or service providers like your ISP, just using a URL. The URL provides access to the Live Traceroute session or a specific Live Traceroute you performed, allowing network operators to troubleshoot problems and see if the changes have an impact on the end-user while avoiding back-and-forth communications.
  
  You can share information about:
  • IP addresses of the Source and the Destination
  • A traceroute from Source to Destination
  • A traceroute from Destination to Source

• Traceroute From Both Directions: Traffic in IP networks is asymmetrical, meaning that the path used from a source to a destination is probably not the same used from the destination to the source. To help troubleshoot issues further, traceroutes give you data from sources and destinations that are in the same ISP – therefore giving you a reverse traceroute to compare the data and catch reverse-path issues.

Periodic Historical Traceroutes

With Periodic Historical Traceroutes, network monitoring agents execute a traceroute at periodic intervals and send the results to the cloud. With periodic, automatic traceroutes, it serves the purpose of solving some of the difficulties I mentioned earlier.

• Automatic Traceroutes:
  As mentioned earlier, some people don’t know when to run a traceroute. With periodic historical traceroutes, you’re sure to have continuous network monitoring data to catch issues as soon as they happen.

• Historical Data:
  The main objective of Periodic Historical Traceroutes is to collect a history of the traceroute to be able to compare the routes when network performance was optimal,  and when it was not. It is perfect for creating a baseline to compare poor network performance when optimal network performance. 

Triggered Traceroutes

Triggered traceroutes are traceroute which are triggered when a network event occurs. The objective of these traceroutes is to catch network issues as soon as they occur to help with the troubleshooting process. 

This is very key for identifying and solving intermittent network issues which may be hard to catch with Live Traceroutes. This also solves the problem of not knowing when to launch a traceroute. When using a traceroute tool along with a Network Performance Monitoring software like Obkio, your software will continuously monitor network performance and trigger a traceroute when it detects a network problem on its own.

Interpreting Traceroute Data

The last difficulty that people normally have when troubleshooting network issues with traceroute are interpreting the data they receive. To help you out, here are some other things to keep in mind:

• Routers Drop Packets or Have High Latencies:
  There are different reasons why a single router can drop traceroute packets or have higher latencies, and it doesn’t necessarily point to any network performance degradation. There’s a general rule of thumb when looking at packet loss from a Traceroute and that is: if the packet loss doesn’t continue with the following hops, then it’s not a network issue.

• Get Hidden Information from Traceroute DNS:
  The hostname of the traceroute hops can provide a lot of information about the real path from the source to the destination. There are four pieces of information that you can decode from Traceroute DNS:
  • ISP operating the router
  • The city where the router is located
  • The router name, number, or unique id
  • The ingress interface or port by which the traceroute packet came on the router

• Traceroutes for MPLS Networks:
  Service providers (SP) and large enterprises use MPLS to manage their networks. There are two aspects of MPLS networks that affect traditional IP traceroutes: ICMP Tunneling and TTL Propagation.

With ICMP Tunneling, latency and packet loss are different even if the network path is the same. So latency may take a big jump and then stay the same for hops that are far away from each other.

With TTL propagation, each time it reaches a router, it is decremented by one. When TTL propagation is disabled, some routers are not visible in the traceroute. 

MPLS networks change the way we look at traceroutes without giving us the exact picture of what is going on, so it’s important to understand how they can alter the data.

Traceroutes are an extremely useful tool to help you troubleshoot network problems. But, they are an advanced tool, which is why it’s important to understand how to use traceroutes and when to be able to fully leverage the information they provide.

You can try Obkio’s complete traceroute tool for free by signing up for their free 14-day trial.