walsh%bbn-labs-b@sri-unix.UUCP (04/24/84)
From: Bob Walsh <walsh@bbn-labs-b> I would like to find out if anyone has used trailers and found them beneficial. My own tests have shown that they have little effect on throughput. My tests used a VAX 780 and a VAX 750 connected to an ethernet by Interlan controllers. I have tried two programs. The first is my own benchmarking program to measure bit rates. The other is ftp. I used the benchmarking program to measure bit rates when writing 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, and 2048 byte sized buffers onto a TCP connection. For the different sized buffers, sometimes trailers produced higher bit rates and sometimes trailers produced lower bit rates. Trailer throughput was always within 3% the throughput achieved without trailers. Similar results were found with ftp. During these tests, socket send and receive buffering high water marks were set at 4096 bytes. Does a different hardware configuration bring forth the 200Kb/sec gain mentioned in the "Networking Implementation" paper found in volume 2C? Yes, I had remembered to turn trailers on for both VAXes. bob walsh