What is Packet Loss? How does it happen?

Where does the term packet loss come from?

When data travels over the internet, this is usually done through small sections of data encapsulated as data called packets. These packets contain a set of information that are sent from the source address to the target device. Usually, such packets will reliably reach from the client to the destination, however, in the case of a packet being lost in transit between two devices, the packet can be lost and never reach its destination. This counts as a lost packet.

When a series of packets are lost in transit, this is where the term Packet Loss comes from. It describes the percentage amount of lost packets between the target and destination.

How can you detect packet loss?

When using diagnostic tools such as ping or traceroute, you may have noticed a term being used called "packet loss." These tools will send a series of packets, usually over the ICMP protocol. The target device will then respond by echoing back the response. By measuring the number of successfully communicated packets, we can then measure the percentage of lost packets between the destination and the client.

How can packet loss occur?

Packet loss often occurs with a client-side networking issue; from being too far away from your wireless network to a faulty network cable -- even a solar flare passing through can interfere with the delivery of traffic.

However, that is not to say that packet loss always occurs due to a client issue! As mentioned above, it only happens to most users as a result of their own network, however, packet loss can occur anywhere throughout a packet's journey to a particular destination. Packet loss can occur due to any one (or more) of the following:

• Interference
  • Poor wiring (damaged shielding on your Ethernet cable), high noise environments (example: your wiring around a microwave)
• Congestion
  • This can be caused by a fibre cut (forcing traffic to be rerouted), DDoS attacks, overloaded routers, or overloaded ports (i.e. a way to think of this is with your home network; assuming you get the full speed of your 100 Mbps Internet package, your network will become "congested" when one user starts a download at full speed while another user attempting to watch a video will have little-to-no bandwidth left)

Conclusion

Having listed some of the most common ways that packet loss can occur, it becomes clear that it is very easy for a packet to be lost (once in a while). If packet loss occurs often to a specific network, it may be an issue of congestion; however, if packet loss only occurs on traffic exiting your network, it will likely be an issue with your wiring, choice of cabling or local congestion.