References, "best" TCP/IP performance

Bryan Koch (btk@clem)
Mon, 26 Oct 87 11:57:13 CST

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.

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