How to Fix Packet Loss in 3 Steps

How to Diagnose and Fix Packet Loss in 3 Steps

While packet loss can seem complex, the process of diagnosing and fixing it can be simple.

Step 1: Diagnose Packet Loss

Diagnosing packet loss typically begins with a single observation: the network is performing badly. The diagnostic process involves several steps aimed at identifying the source of the issue.

Test Wired Connections

First, it’s crucial to test wired connections between both ends of the communication – this could be between a workstation in an office and an enterprise’s remote application server. To establish where the slowdown is, ping the server as closely as possible.

Ideally, this would be the remote endpoint, but firewalls may prevent direct pinging, in which case the LAN interface on a router can serve as a substitute.

The goal is to observe whether packet loss occurs during this test.

• If packet loss is detected, the problem is often either insufficient bandwidth or a faulty network interface controller, like an ethernet cable. In such cases, it’s important to trace the network route and begin troubleshooting from a midpoint, which typically reveals whether the issue lies on one side or the other.

• If no packet loss is detected initially, further testing is required. This may involve increasing the number of pings or using larger packet sizes to stress the network and expose any potential issues. If these steps do not yield results, the next phase involves examining Quality of Services (QoS) policies and interface statistics across the entire path between the endpoints, to identify any configuration or hardware issues affecting packet flow.

Reconsider the Diagnosis

If these efforts do not pinpoint the problem, it becomes necessary to reconsider the diagnosis.

At this stage, the only definitive method for detecting packet loss is to perform simultaneous packet captures at both endpoints. Tools such as Wireshark or traceroute can be employed, either directly on the hosts or via network taps and sniffer network devices.

It’s how you can assess whether the packet reached the router in the first place, or whether the response was lost on the reverse path.

Consider Alternative Explanation

Finally, it is important to consider alternative explanations rather than simple packet loss alone.

In some cases, what appears to be packet loss may actually be the result of server-side delays, such as when a database is moved to a location with higher latency, leading to slower query responses – rather than data loss.

Step 2: Act on the Diagnostics

Once you know exactly where the source of the network issue is, it’s time to take action.

• If the issue stemmed from a faulty ethernet port or cable, this can be replaced relatively easily after its identification.
• If it’s a deeper issue within a device’s network interface controller, this can also be replaced.

Software Issues

Sometimes it’s not the physical components that can create heavy packet loss, but the firmware your networking hardware is running off.

For instance, at the heart of network switches’ ability to ferry packets around a network is the routing table:

• if an error crops up – whether through a misconstrued update or erroneous bug – packets get sent to the wrong destination and dropped entirely at an unacceptable rate.
• If a router has a routing issue, but doesn’t respond with an error message, it’s often due to a mechanism known as rate limiting. Some routers, especially those built for home and small offices, have built-in rules to limit how frequently they send ICMP TTL Exceeded messages. These rules typically exist to protect the router’s CPU and are in many cases unconfigurable. When routers don’t send error messages at all, it can make it unnecessarily difficult to troubleshoot network issues in the future.

Routing tables aren’t the only breakable component within a router’s firmware: sometimes, the buffer overflow can be overwhelmed. This stores data temporarily, to better handle network spikes. However, should the traffic increase beyond that buffer limit, packets are discarded to prevent congestion.

Fixing these issues ties into some core components of network resilience.

Step 3: Prevent Packet Loss

High packet loss can be a sign that your network infrastructure needs a degree of TLC. It doesn’t have to break the bank, but consider these three preventative measures:

Increase Bandwidth

If packet loss results primarily from network congestion, often following significant growth or changes in network architecture, increasing bandwidth can help.

By allowing more data to flow through at once, you reduce bottlenecks and delays. However, remember that a network performance depends on the integrity of each component: if any part of the system exceeds its capacity, it can slow down the entire data flow.

If your internal network seems sufficient, be sure to check the firewalls and routers that the packets pass through for any issues.

Implement Deep Packet Inspection (DPI)

Deep Packet Inspection (DPI) offers a more sophisticated way to filter network traffic by examining the contents of data packets in real-time. DPI can identify, classify, and then reroute or block packets based on their content, which helps streamline traffic and reduce congestion.

Often offered by stateful firewalls, this method also allows administrators to prioritize important packets, ensuring that high-priority data is processed faster, reducing the risk of packet loss for critical information.

Optimize Network Configurations

Misconfigured networks are a common cause of packet loss issues, whether it’s due to incorrect settings on individual devices or inconsistencies across multiple systems.

These configuration errors can disrupt traffic and cause data to be lost. To prevent this, IT administrators should implement a strong network configuration management system, ensuring devices are consistently set up and regularly monitored for any issues.