SLIP Serial packet *overruns*

SLIP Serial packet *overruns*

Post by Bart Kin » Sat, 09 Jul 1994 05:17:33



Hay all,
I have a problem with my local pointopoint SLIP connection. During the
connection, and especially during transfer of large chunks of data, I get
about 20% Packet Overruns in the Linux box. ( I give a IFCONFIG to look at
them).

I connect my Windows computer to the Linux with a SLIP link, using
SLIPLOGIN. Both machines are 486, with 16450 Serial cards, use 38400 baud.
In Windows for Workgroups 3.11, I am using Trumpet Winsock, which is setup
with compression and *hardware handshake* enabled.

I use a full null-modem cable. No other processes are running on either
machine, except for the Internet /Ethernet link from the Linux box to the
Routers.

I have also tried 19200 baud, but no improvement.
After about 5000 packets, I see about 1200 overruns on RX *and* on TX both!

Transfers become very slow, due to IP retries timeouts

Anybody knows what the reason is of this problem? Who controls the hardware
handshake on Linux: SLIPLOGIN or the Kernel???

Any help welcome!

Greetings, Bart.

 
 
 

SLIP Serial packet *overruns*

Post by Karl Key » Fri, 08 Jul 1994 23:45:09



Quote:>During the connection, and especially during transfer of large chunks of data, I get
>about 20% Packet Overruns...[stuff deleted]..

>Both machines are 486, with 16450 Serial cards, use 38400 baud.

I hate to say this but I don't think 16450s are up to much at all! For anything
at all serious (especially in a multi-tasking environment) you're going to need
16550A's. They're cheap - that's the good part!

Karl

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1. Meaning of RX/TX packet overruns in SLIP?

I have slip up and running fine in principle. The connection is via two
14400baud modems and 19200baud modem<->computer on both sides. However,
I get only an ftp transfer rate of a little less than 1 KB/sec.
ifconfig states both for RX and TX a overrun rate which is a bit below the
corresponding packet count. No errors or dropped packets. If I ftp a file
on one vt and watch the output of ifconfig permanently on another vt both
counts (packet count and overrun count) increase almost equally.

$mtu set in dip to 1500
slip server reports an mtu of 1500

my computer is a 486/DX50, 16MB, modem at cua1 with 16450.

I took a look at the kernel and the ifconfig sources but got lost in it.

Thanks for any help,
   Andreas

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