From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 27 Sep 1999 10:14:35 +1000 Message-Id: <199909270014.KAA25683@tango.anu.edu.au> From: Paul Mackerras To: rrschulz@cris.com CC: linuxppc-user@lists.linuxppc.org, linuxppc-dev@lists.linuxppc.org In-reply-to: (message from Randall R Schulz on Sat, 25 Sep 1999 18:49:14 -0700) Subject: Re: Inbound TCP Circuits over PPP Stall; MTUs and Kppp Reply-to: Paul.Mackerras@cs.anu.edu.au References: Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: Randall R Schulz wrote: > By using tcpdump, I have discovered what seems to be a relevant fact: > When the stream stalls, the sending side (always the remote) is > resending the same range of bytes (sequence numbers) over and over > again with an inter-packet arrival time that increases gradually > until it reaches about two minutes where it holds until one side or > the other gives up and closes the stream. Each such packet has the > PUSH flag set and elicits an ACK from my system, but for whatever > reason, the remote just keeps sending repetitions of a packet > containing the same range of sequence numbers (with a total of 1448 > data bytes each). This sounds like the remote system isn't getting the ACKs (or they are getting corrupted). Try putting the `novj' option in your ~/.ppprc file and see if that makes any difference. > I have captured the tcpdump output from one of these "sessions" > (beginning when I clicked a FTP URL link in Navigator through until I > cancelled the stalled transfer after several repetitions at the > two-minute inter-packet arrival time. There are 140 lines of tcpdump > output. If anybody can make use of this in diagnosing the problem, > I'd be happy to send it... I would be interested to see it. > This problem is easily repeated, Hopefully we can track it down then. > I'd like to try changing my PPP MTU from 1500 to 1514, but I don't > know where to control it under kppp and the documentation doesn't > mention it. Try making yourself a ~/.ppprc file containing the line `mru 1514'. In fact the MTU is determined by the MRU (max receive unit) that the peer asks for so you can't directly control it except to give a maximum value with the mtu option. Paul. ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/