Terminal server efficiency


Jim Warner (saturn!eshop@jade.Berkeley.EDU)
16 Nov 87 01:11:26 GMT


How important is the offered TCP window size for Ethernet
terminal servers?

Our Bridge LS1 terminal server offers a maximum window size
of 164 bytes. Our Micom terminal server offers a 384 byte
window. The small window forces our computers to send a full
screen update as many small packets instead of fewer larger
packets. It seems to me that this is expensive in terms
of CPU bandwidth both for the connected computer and any
intervening gateways. What do people think? Is this important?

Here's some data. I logged in to a 4.3BSD computer, read a 7
screen file (154 line, 10430 byte) with unix 'more' and logged out.
In all cases the terminal baud rate was 9600. "Total packets"
includes those necessary to log in and give the commands.

Terminal software Max Offered Total packets
attached to version rcv window (both ways)

Bridge LS1 13000 164 481
Micom NTS-100 V1.3-AC 384 241
VAX 750 4.3BSD 4096 159

Our Micom NTS-100 is running software that is still in beta test.
The production software offers a 320 byte window.



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