Originally Posted By: Quattro Pete
Some of the switches, like that SMC that Volvohead posted support jumbo frames. Have any of you experimented with it? Has it improved speeds (assuming all your devices can support it, too)? Is it a feature worth getting?
Check
this article about jumbo frames.
From the article:
Why Jumbo Frames?
Every data unit on a network has to be assembled by the sender, and its headers have to be read by the network components between the sender and the receiver. The receiver then reads the frame and TCP/IP headers before processing the data. This activity, plus the headers added to frames and packets to get them from sender to receiver, consumes CPU cycles and bandwidth.
Sending data in jumbo frames means fewer frames are sent across the network. This generates improvements in CPU cycles and bandwidth. A single 9k jumbo frame replaces six 1.5k standard frames, producing a net reduction of five frames, with fewer CPU cycles consumed end to end. Further, only one TCP/IP header and Ethernet header is required instead of six, resulting in 290 (5*(40+18)) fewer bytes transmitted over the network.
It takes over 80,000 standard Ethernet frames per second to fill a gigabit Ethernet pipe, consuming a lot of CPU cycles and overhead. Sending the same data with 9k jumbo frames, only 14,000 frames need to be generated, with the reduction in header bytes freeing up 4 Mbps of bandwidth.
These savings in CPU cycles and bandwidth can produce some significant increases in network performance. In a 1999 study on jumbo frames over gigabit Ethernet, "Microsoft, Sun, Compaq, Hewlett-Packard, and IBM all recorded at least 50% increases in TCP throughput with reduced CPU utilization on single- and multi-processor systems using jumbo frames."
