Fragmentation

Fragmentation significantly reduces overall system performance through causing applications to retransmit original data if the distent end application is unable to utilize fragmented packets. This can become a compounding effect as the sending application continues to retransmit packets which are now well known to become fragmented in flight, causing more retransmissions of the same packets leading to more fragmentation. The overall effect creates conditions of extreme local congestion, application loss, and poor network utilization. In these environments the ration between “goodput”, the actual usable data successfully delivered, versus throughput, the overall amount of transport medium being used regardless of quality, very quickly degrades. As seen in the image below (utilizing the same application and transport medium as in our Latency example), the introduction of encryption has heavily degraded the performance of the connection. This erosion of performance is caused by packet fragmentation introduced by the encryption process. The encryptors, in this example an AES256 VPN and a high speed bulk encryptor must insert x amount of overhead data on every packet, if the packet is already sized at (MTU-x)+1 bits then it will be fragmented every time. Of a rated 5Mb/s capacity the performance dropped from ~557kb/s with zero errors to ~121kb/s with a 6.3% error rate.