How to Monitor Network Performance with Traceroutes
When it comes to troubleshooting network problems and monitoring network performance, there are a variety of tools available.
12:53 12 November 2020
Each tool plays an integral part in optimizing network performance, but it’s important to understand which tools you may need in certain situations.
Traceroute is one of the most popular tools that network engineers and IT geeks use to troubleshoot networks. Invented in 1987, Traceroutes are still highly relevant and frequently used today.
To help you learn more about Traceroutes and the role they play in monitoring network performance I’ll be covering some topics related to network monitoring with Traceroutes.
What Are Traceroutes
First invented in 1987, Traceroutes are considered the most commonly used tool to troubleshoot network issues. A traceroute traces the IP route from a source to a destination inside of an IP network. It collects data to show users the routers and round-trip latency from the source to each of the routers.
Traceroutes works using an 8-bit field in the IP Header, called Time-to-live (TTL). The traceroute software uses the TTL to discover the routers between a source and a destination. Learn more about how traceroutes work in the full article.
There are many different traceroute tools on the market, but when it comes to monitoring network performance with traceroutes, deploying an end-to-end monitoring software with traceroute capabilities will give you a more complete overview of network performance to help you troubleshoot network problems faster.
Obkio’s Network Performance Monitoring Software offers a Live Traceroute feature, used in combination with the network monitoring sessions. Live Traceroutes allow users to calculate the forward and the reverse traceroutes with latencies and packet loss in real-time. It’s the perfect tool to pinpoint the location of network performance issues.
Users can share the results with their team but also with third-parties such as IT consultants or service providers. With access to the live traceroute feature, everyone will be able to troubleshoot network problems as fast as possible.
Pinpoint Network Issues with Traceroutes
You can identify network issues with traceroutes by analyzing two metrics for each hop or router: latency and packet loss. The latency refers to 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 which never received a response out of the total number of sent packets.
Traceroutes monitor both of these important metrics, and identify network issues based on the results.
Why Routers Drop Data 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.
Decode 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
How to Catch Reverse Path Issues
When looking at a traceroute, people often forget that traffic on the Internet is asymmetrical most of the time. This is called the Hot Potato Routing.
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
Share a Traceroute With Your ISP
Whether a network problem is located in your ISP’s network or somewhere else on the Internet, reach out to your ISP’s NOC (Network Operation Center) to help troubleshoot. Explain to them the issue with the following information:
- IP addresses of the Source and the Destination
- A traceroute from Source to Destination
- A traceroute from Destination to Source
- Historical traceroutes where everything is running fine (if you have them)
- A way to replicate the issue (more on that later!)
A tool like Obkio’s traceroute tool allows you to share a traceroute with your ISP so they get all the data they need to help you troubleshoot.
Load Balancing and Multiple Paths on Traceroutes
To increase capacity between routers, many IT specialists choose to have more than one connection between them. If at any point a router does not support higher speed interfaces, the only solution to support a higher capacity would be to aggregate two or more ports together.
There are usually two possible configurations that allow you to set up multiple connections between routers: the Link Aggregation and the Equal Cost Multi Path (ECMP).
For the more accurate data, you need a Traceroute software that allows you to choose which ports to use. Therefore, you can use ICMP to have an easy to read traceroute or use TCP (or UDP) with random ports to see the full paths between the source and the destination.
Traceroutes for MPLS Networks
Service providers (SP) and large enterprises use MPLS (Multiprotocol Label Switching) networks to better segment and 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 the 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 on 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. Since they are an advanced tool, it’s important to understand how to use traceroutes and when, to be able to fully leverage the information they provide!