Slip Overruns

Slip Overruns

Post by Rainer Canava » Fri, 17 Sep 1999 04:00:00



Hi,

for now i have no cable to connect the ethernet port of my sparcbook,
so i'm using a slip connection to my PC running Linux.

Now if i run ifconfig sl0, there's an alarming rate of TX and
RX overruns, and i just can't believe that. I looked in dejaNews,
and people suggested in the past, that this were the just an indicator
for compressed headers. Is that true? I also believe that
the performance is pretty bad - i get only around 2k/s
on a 38400bps link so this would be an indicator for some overruns...
I have the MTU the same on both sides. What more is there to do.
Oh, yes the SparcBook runs Solaris 2.5.1, if that matters.

          RX packets:396627 errors:0 dropped:0 overruns:96006 frame:0
             compressed:0
          TX packets:174520 errors:0 dropped:0 overruns:124451 carrier:0

Rainer M. Canavan

 
 
 

Slip Overruns

Post by Rob van der Putte » Sat, 18 Sep 1999 04:00:00


Hi there


> Now if i run ifconfig sl0, there's an alarming rate of TX and
> RX overruns, and i just can't believe that.

Did you check your flow control (should be bidirectional RTS / CTS flow
control)?
Do you use 16550's or older com port chips?

Regards,
Rob

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Slip Overruns

Post by Rainer Canava » Sat, 18 Sep 1999 04:00:00



> Hi there


> > Now if i run ifconfig sl0, there's an alarming rate of TX and
> > RX overruns, and i just can't believe that.

> Did you check your flow control (should be bidirectional RTS / CTS flow
> control)?

Isn't the flow control set by software, i.e. slattach? The cables & the
ports should do hw handshake.

Quote:> Do you use 16550's or older com port chips?          

It's one of the PIIX (Intel PCI->Isa bridge with Floppy, Parallel, Serial,
whatever) integrated serial Ports. It really should be fast enough. If
there's a problem, I'd expect it to be somewhere in the slip setup.

ttyS03 at 0x02e8 (irq = 10) is a 16550A

The interrupt is correct, I have a clock-doubled Serial port on ttyS1
(irq=3) and therefor I have moved this port to irq 10.

Quote:> Regards,
> Rob

Rainer
 
 
 

1. SLIP: overruns and >38400 baud?

2 Questions:

        1) How do I get slip to run >38400 baud, I tried 57600 but
           dip forces the speed to 38400 -- is that a Linux limitation?

        2) after some slip usage ifconfig reports:

sl0       Link encap UNSPEC  HWaddr
00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
-00
          inet addr 130.62.133.194  P-t-P 130.62.133.47  Mask 255.255.0.0
          UP POINTOPOINT RUNNING  MTU 296  Metric 1
          RX packets 4235 errors 0 dropped 0 overruns 4061
          TX packets 5994 errors 0 dropped 0 overruns 5691

Is it normal to have that many overruns?  I am using a 16550A UART.
Running some sample ftp file transfers I get anywhere from
1.5 Kby/s (compressed files) up to 3.4 Kby/s (uncompressed text),
which seems to indicate the transfer speed isnt suffering.  Still
the overruns reported is disturbing.

--
David Lai

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