Neil,
Ping works without any losses (0% loss), but traceroute does not. I found
out that ping uses ICMP and traceroute UDP. I do not have any idea why this
is happening. To my knowledge the iptables is turned off. I am going to try
the ttcp but do you have any idea why this could be happening?
Gkikas
-----Original Message-----
From: lam-bounces_at_[hidden] [mailto:lam-bounces_at_[hidden]] On Behalf Of
Neil Storer
Sent: Wednesday, August 04, 2004 3:43 PM
To: General LAM/MPI mailing list
Subject: Re: LAM: LAM freezes, please help!
Gkikas,
If "ping" is working without any packets lost. e.g.
ping -c 100 host-abc
100 packets transmitted, 100 received, 0% loss
Then your network is probably OK. You should do the "pings" from each node
to each other node to fully test the system.
TTCP is a simple client-server application that uses SOCKETs to send data.
It doesn't use MPI however, MPI uses SOCKETs (by default), so if TTCP also
works OK, you have eliminated hardware and the underlying TCP/IP and routing
as sources of the problem.
For information on TTCP + how to get the source, use "google" or see:
http://www.nps.navy.mil/cs/su/cs4550/proj1.1.htm
The MAN page on my system is:
NAME
ttcp - test TCP and UDP performance
SYNOPSIS
ttcp -t [-lbuflen] [-s] [-nnumbufs] [-pport] [-u] [-D] [-L]
[-Aalign]
[-Ooffset] [-v] host [<in]
ttcp -r [-lbuflen] [-s] [-pport] [-B] [-Aalign] [-Ooffset] [-u] [-v]
[>out]
DESCRIPTION
Ttcp times the transmission and reception of data between two
systems using the UDP or TCP protocols. It differs from
common "blast" tests, which tend to measure the remote inetd as much
as the network performance, and which usually do not
allow measurements at the remote end of a UDP transmission.
Ttcp.c should be compiled for both ends of the path to be test.
It uses sockets and is easy to port to most machines
based on 4.3BSD.
The transmitter should be started with -t after the receiver has
been
started with -r. Test lasting at least tens of
seconds should be used to obtain accurate measurements.
Graphical presentations of throughput versus buffer size for
buffers ranging from tens of bytes to several "pages" can illuminate
bottlenecks.
Options
-t Transmit mode.
-r Receive mode.
-u Use UDP instead of TCP.
-llength Length of buffers in bytes (default 8192).
-nnumbufs Number of source buffers transmitted (default 2048).
-pport Port number to send to or listen on (default 5001).
-D If transmitting using TCP, do not buffer data when sending
(sets the TCP_NODELAY socket option).
-s If transmitting, do not source a data pattern to network;
use stdin instead. If receiving, do not sink or discard,
but print all data to stdout.
-B When receiving and using the -s option, only output
full
blocks, using the block size specified by -l. This
option is useful for programs that require complete
blocks,
like tar(1).
-Aalign Align the start of buffers to this modulus (default
16384).
-Ooffset Align the start of buffers to this offset (default 0).
For
example, "-A8192 -O1" causes buffers to start at
the second byte of an 8192-byte page.
-v Verbose: print more statistics.
-d Set the SO_DEBUG socket option.
--
+-----------------+---------------------------------+------------------+
| Neil Storer | Head: Systems S/W Section | Operations Dept. |
+-----------------+---------------------------------+------------------+
| ECMWF, | email: neil.storer_at_[hidden] | //=\\ //=\\ |
| Shinfield Park, | Tel: (+44 118) 9499353 | // \\// \\ |
| Reading, | (+44 118) 9499000 x 2353 | ECMWF |
| Berkshire, | Fax: (+44 118) 9869450 | ECMWF |
| RG2 9AX, | | \\ //\\ // |
| UK | URL: http://www.ecmwf.int/ | \\=// \\=// |
+--+--------------+---------------------------------+----------------+-+
| ECMWF is the European Centre for Medium-Range Weather Forecasts |
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