Path: utzoo!attcan!uunet!husc6!think!ames!pasteur!ucbvax!NNSC.NSF.NET!craig
From: craig@NNSC.NSF.NET (Craig Partridge)
Newsgroups: comp.protocols.tcp-ip
Subject: re: telnet over x.25 tcp/ip costs?
Message-ID: <8811281453.AA08751@ucbvax.Berkeley.EDU>
Date: 28 Nov 88 13:12:51 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 32


> I would appreciate hearing (anecdotal) reports of the costs people have
> observed running tcp/ip over international x.25 networks.  I am
> particularly interested in how the packet charges add up when there is
> sporadic interactive use with telnet-like applications.

Dave:

    Two weeks ago I had the interesting experience of telneting in to
read my mail in Boston from an NTT site in the Tokyo area.

    Regarding packet charges, two observations are likely to be of interest
to you:

    (1) International X.75 gateways typically only allow X.25 windows
	of size 2.

    (2) Because of (1) the Nagle algorithm + type ahead really helps.
	The round-trip times were on the order of 20-30 seconds, so
	waiting for the first character to be echoed was silly.  I just
	typed in my commands as fast as I could.  When the ack for
	the first character came back, by typing ahead and allowing
	the Nagle algorithm to buffer up the data, I ensured that
	there was lots of data to go in the next packet.

In other words, if you use the Nagle algorithm you should only very
rarely see one character per packet.  And if you don't use the Nagle
algorithm you probably won't be able to use the connection at all --
2 characters every 30 seconds just doesn't cut it, while once I got
to typing ahead, I found the connection usable, if slow.

Craig