June 7, 2012

Adapters Help Mitigate IP-Packet Fragmentation

Mass.-based network-adapter maker Napatech has added a new feature it says  “intelligently identifies” fragmented IP packets, providing OEM vendors with an off-load tool to increase performance in networks with many fragmented packets.

According to Napatech, IP fragmentation occurs when large frames are split into smaller frames to suit the transmission characteristics of the network, meaning a large IP/TCP/HTTP frame will be split into two frames, where the first frame holds the IP, TCP and HTTP network headers together with the first part of the payload data, and the second frame holds an IP header together with the remaining payload data.

“This presents a challenge to network analysis appliances as the second frame does not contain any high level protocol headers, which makes it impossible for simple hardware filters and hardware flow distribution solutions to handle the fragment frames in a meaningful way,” it adds.

The Napatech IP fragmentation solution, now available on all 1 Gbps, 10 Gbps and 40 Gbps network adapters, reportedly solves this problem by identifying which fragments that belong to the same original IP frames, allowing fragmented IP frames can be filtered and can be distributed in the same way as non-fragment IP frames.

“Up to 33 percent of network traffic can be fragmented, and this creates an extra workload for network appliance vendors as fragments must be identified and reassembled before data can be analyzed,” notes CEO Henrik Brill Jensen. “By identifying IP fragments and collecting them for reassembly and analysis, Napatech intelligent network adapters can help relieve this work load.”

He continues, “IP reassembly is often the first step required before any IP data analysis can be performed. With this feature enhancement, we can help increase performance and enable new features to be implemented as more processing power is freed up for the application.”