help getting pppd to use XON/XOFF flow control...?

Raymond Blum (
Wed, 22 Dec 1999 22:34:56 -0500

I have a machine that has been running pppd to do IP Masquerading for
my little network; everything was fine, then pppd starting complaining
about the connection. Then without warning pppd stopped getting
responses from the modem when using chat to send modem commands. The
modem RD & SD lights flash but no response was received from the modem
at all. (The TR light does come on when pppd runs chat)

I used other machines to diagnose the modem, which seems fine, and have
figured out that I can use minicom to talk to the modem as long as I
have hardware handshaking OFF and XON/XOFF on. I used stty to make sure
that hardware flow control was enabled on /dev/modem. So I assume that
something has gone wrong with my UART or other component of my on-board
serial port and that the CTS pin is not working.

I read the HOWTO and man pages and figured that I could use pppd with
XON/XOFF by using nocrtscts and xonxoff options. I also used stty to set
-crtscts and ixon ixoff. No effect. I have "escape FF" and "asyncmap
20A0000" options specified.

Can someone tell me what I am missing that is needed to get pppd to use
software flow control?

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