btk@clem (Bryan Koch) (10/26/87)
While TCP/IP performance is constrained by a number of factors (buffer, window, and transfer sizes; speed of checksum calculation; hardware interrupt capacity; I/O bandwidth of supporting hardware), the situation is not nearly as grim as that assumed by Guru Parulkar's recent request for information. We have seen TCP/IP data rates (memory to memory w/data validation by receiver) of 11 Mbit/second over NSC HYPERchannel media. This was seen using 16 Kbyte blocks (MTU) and a 48 Kbyte TCP send/receive space between two CRAY-2 systems. Local (software) loopback rates for the same situation exceeds 60 Mbit/sec using 32KB MTU and 16KB send/receive space on a Cray X-MP/48. TCP and IP do have problems, but there is nothing there which constrains performance to the 1-8 Mbit/sec range. It would appear from our results that TCP/IP may well be appropriate protocols for use with FDDI media, though performance over FDDI will be heavily dependent on the TCP/IP implementation and parameters. -Bryan Koch Cray Research, Inc. btk%hall.cray.com@umn-rei-uc.arpa