From: Glynn Clements (
Date: Fri Jul 13 2001 - 09:32:06 EST wrote:

> I connected two PCs back-to-back via a cross cable on COM2 ports.I
> configured serial interfaces using
> # slattach -p slip -s 9600 /dev/ttyS1
> I assigned IP addresses and added route to the routing table.I configured
> everything and I run ping command.
> ping results are not what I expected. because delay time is about 390.046
> ms. this is to much.
> I want it to be about 1 ms or less.

Clearly a 1ms ping (with the default packet size of 64 bytes) is
impossible over a 9600bps connection. Assuming 1 start bit and 1 stop
bit, the transmission time each way is 64 * 10 / 9600 = 0.067 = 67ms,
which gives a minimum round-trip time of 133ms. I don't know why
you're getting nearly three times this figure, though.
> and is there another way of connecting two PCs via a cross cable
> efficiently?

If you're concerned about speed, bear in mind that a 9600bps link is
10,000 times slower than 10Mbps ethernet.

Glynn Clements <>
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This archive was generated by hypermail 2b29 : Sun Jul 15 2001 - 21:00:25 EST