[ILUG] ISDN Ping Times.

[Kenn Humborg]

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.

Later,
Kenn