Meaning of RX/TX packet overruns in SLIP?

Meaning of RX/TX packet overruns in SLIP?

Post by Andreas Lem » Wed, 20 Apr 1994 04:57:01



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

 
 
 

1. sl0 RX overrun 20 TX overrun 57

Hi all!

Any comment about the following?

I have two Linux boxes connected via CSLIP and direct wire.
No matter whether the speed is 9600, 19200 or 38400 bauds.
Kernel version is 1.1.37 (but 1.0.8 acts in a similar way).

Routing is set up correctly, ping works brilliantly in both
directions. Telnet works so slowly that it times out before
I can log in. Ftp also works very slowly. ps shows that
in.telnetd on the server side is running. Ifconfig shows
that some overrun of packets occurs on sl0 (ethernet works OK):

----------------------------------------------------------
pygalik:/etc/rc.d# ifconfig
lo        Link encap Local Loopback
inet addr 127.0.0.1  Bcast 127.255.255.255  Mask 255.0.0.0
UP BROADCAST LOOPBACK RUNNING  MTU 2000  Metric 1
RX packets 0 errors 0 dropped 0 overrun 0
TX packets 52 errors 0 dropped 0 overrun 0

sl0       Link encap Serial Line IP
inet addr 200.40.40.95  P-t-P 200.40.40.96  Mask 255.255.255.0
UP POINTOPOINT RUNNING  MTU 296  Metric 1
RX packets 3058 errors 0 dropped 0 overrun 20
TX packets 3293 errors 0 dropped 0 overrun 57

eth0      Link encap 10Mbps Ethernet  HWaddr 00:00:E8:C3:D4:97
inet addr 193.40.127.4  Bcast 193.40.127.255  Mask 255.255.255.0
UP BROADCAST RUNNING  MTU 1500  Metric 1
RX packets 4345 errors 0 dropped 0 overrun 0
TX packets 4987 errors 0 dropped 0 overrun 0

pygalik:/etc/rc.d# netstat -i
Kernel Interface table
Iface   MTU Met  RX-OK RX-ERR RX-DRP RX-OVR  TX-OK TX-ERR TX-DRP TX-OVR Flags
lo     2000   0      0      0      0      0     52      0      0      0 BLRU
sl0     296   0   3066      0      0     21   3308      0      0     63 PRU
eth0   1500   0   5045      0      0      0   5919      0      0      0 BRU
pygalik:/etc/rc.d#
---------------------------------------------------------------------------
Can anyone explain, what does this overrun mean
and what influence has it on performance?

                                        Anto,

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