Fragments On The Wire

Intro

As networks become more complex and diverse, the issue of fragmentation has become increasingly important to network administrators. Fragmentation is a process in which data packets are broken into smaller pieces to traverse through networks with varying Maximum Transmission Unit (MTU) sizes. While this process is necessary for data to be transmitted over different networks, it can also have significant impacts on network performance and security. In this technical blog post, we’ll explore the effects of fragmentation on network traffic and equipment, and discuss how network administrators can mitigate these impacts for optimal network performance.

What is it

Fragmentation is a process in which data packets are broken into smaller pieces to traverse through a network that has a smaller Maximum Transmission Unit (MTU) size than the original packet. When the packet reaches its destination, the smaller pieces are reassembled into the original packet. This process is necessary to ensure that data can be transmitted over different networks with varying MTU sizes.

Possible impact

Fragmentation can have a significant impact on network traffic and network equipment. Here are some ways fragmentation can affect network performance:

1. Increased network latency: Fragmentation can increase network latency, which is the time it takes for data to travel from the sender to the receiver. When a packet is fragmented, it takes longer to transmit the smaller pieces, increasing the overall time it takes for the packet to reach its destination.
2. Reduced network throughput: Fragmentation can also reduce network throughput, which is the amount of data that can be transmitted over a network in a given period of time. When packets are fragmented, it takes longer to transmit the smaller pieces, which reduces the overall amount of data that can be transmitted over the network.
3. Increased CPU usage: Fragmentation requires additional processing power from network equipment, such as routers and switches, to reassemble the packets at the receiving end. This can increase the CPU usage on network devices, which can lead to slower performance.
4. Security risks: Fragmentation can also be used as a technique for malicious attacks, such as denial-of-service (DoS) attacks. Attackers can use fragmentation to overwhelm network equipment with an excessive number of packets, leading to network downtime.

Mitigation

To mitigate the impact of fragmentation on network performance and security, it is essential to understand the MTU sizes of the networks and devices being used. The MTU size determines the maximum size of a packet that can be transmitted over the network. In general, the larger the MTU size, the fewer packets will need to be fragmented, reducing the impact on network performance.

However, increasing the MTU size can also lead to other issues, such as increased packet loss and decreased reliability. Therefore, it is essential to find a balance between MTU size and network performance. Network administrators can use tools such as ping and traceroute to determine the optimal MTU size for their network.

In conclusion, fragmentation is a necessary process for data to traverse through networks with different MTU sizes. However, it can have a significant impact on network performance and security. Understanding the MTU sizes of networks and devices and finding the optimal MTU size can help mitigate the impact of fragmentation on network performance and security.