What is packet loss and how to reduce that?

PACKET LOSS

Packet loss is the failure of one or more transmitted packets to arrive at their destination. This event can cause noticeable effects in all types of digital communications. Packet loss occurs when one or more packets of data travelling across a computer network fail to reach their destination. Packet loss is typically caused by network congestion. Packet loss is measured as a percentage of packets lost with respect to packets sent.

There are many reasons for performance issues, but in this post, we'll focus specifically on packet loss. The following four causes are among the most common times you could encounter dropped packets:

1. Link Congestion

Your data must travel through multiple devices and links during its trip across your network. If one of these links is at full capacity when your data arrives, then it must wait its turn before being sent across the wire (this is known as queuing).

If a network device is falling very far behind, it won’t have room for the new data to wait (queue), so it does the only thing it can, which is to discard the information.

Recovery

There are two main ways to help reduce the effect of packet loss due to network congestion:

• 1. Increase the bandwidth of the congested link(s).
• 2. Implement Quality of Service (QoS) to give priority to real-time traffic. This will       not help the congestion of the link, but it can give priority to applications like             voice or video which lowers the likelihood of a drop.

2. Device (Router/Switch/Firewall/etc.) Performance

If your bandwidth is adequate, you can still face an issue if your router/switch/firewall is not able to keep up with the traffic.

Let’s take a scenario where you recently upgraded a link from 1Gb to 10Gb because traffic reports show that you were at full capacity during peak hours of the day. After the upgrade, your charts show the bandwidth going up to 1.5Gb, but you are still experiencing network performance issues. The issue could be that the device is not able to keep up with the traffic, and you have hit the maximum throughput your hardware can provide.

Recovery

You must replace the hardware with a new appliance that can handle your maximum throughput, or potentially cluster additional hardware to increase your throughput.

3. Software issues (bugs) on a network device

While we can hope that the software written for our network devices is perfect, I can assure you that it is not. These network devices are extremely complex, and it is a matter of time before you stumble upon a bug.

These bugs can cause new features to not work at all when you deploy them, or can go undetected for awhile before you may notice performance issues.

Recovery

You must upgrade the software on the affected device(s).

4. Faulty Hardware or Cabling

Your traffic report shows that your links are not over-utilized, and the hardware utilization is within specification. The next common issue that can lead to drops would be a physical component that is malfunctioning.

If hardware is not working properly, it will usually lead to error messages being seen on the console of the device or within system logs.

Recovery

The faulty hardware must be replaced, or the fault link must be repaired.

These are the most common reasons for packet loss on a network, but there are many other reasons that can contribute to packet drops. The best way to determine the root cause is through a network assessment and detailed troubleshooting.

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