[ILUG] ISDN Ping Times.
kenn at linux.ie
Sun Sep 10 22:07:49 IST 2000
On Sun, Sep 10, 2000 at 09:58:57PM +0100, John Ronan wrote:
> I've found something which I'm going to have to investigate and its really
> annoying. I take a file, say a couple of hundred K and try and scp it
> from my machine to another, doesn't matter where.
> jronan at fluffy.xxxxxx.com's password:
> nmap.tgz | 168 KB | 84.0 kB/s | ETA: 00:00:01 |53%
> Netstat output:
> Proto Recv-Q Send-Q Local Address Foreign Address State
> tcp 0 52892 195.X.XX.XXX:1022 fluffy.xxxxxx.com:ssh ESTABLISHED
> That's it dead connection. Looking at the serial tx/rx lights shows tx
> for a while, then goes out. After that I get a (very) periodic rx light,
> followed by a burst of data from the tx light. In summary it takes about
> 7-8 minutes to transfer about 6K. The Uarts are 16550A's. I'm using
> wvdial with the speed setting of 115K2.
> Under windoze 98, using the USB port these symptoms don't appear.
> It could be my serial ports. It could be firmware in the TA, I'll try the
> 3com site for an upgrade, but basically any opinions/suggestions would be
> gladly accepted.
Get a tcpdump at both ends. Examining those should tell you if the problem
lies at one end or the other. E.g., is your local machine re-transmitting
all the time and not receiving ACKs from the remote? If so, is the remote
receiving your packets and transmitting ACKs?
Try pinging with large (1400-byte) packets when the transfer freezes like this.
See ping manpage.
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