Thank you for your fast reply....
so i can say that for example when i send a array with integers from node 0
to node 1 there are transported with tcp? ...but how informations
are transportet between the lam daemons (lamd)? And when i use lam mpi
between far away nodes (cluster) for example use over the internet...
is this not dangerous because udp is connectinless? where can i get
informations about network characteristics of LAM MPI?
thank you
----- Original Message -----
From: "Prabhanjan Kambadur" <pkambadu_at_[hidden]>
To: "General LAM/MPI mailing list" <lam_at_[hidden]>
Sent: Thursday, June 17, 2004 11:11 PM
Subject: Re: LAM: transport protocol and rsh ssh configuration
>
> Hi,
>
> We do make use of multiple protocols in LAM. TCP connections are used for
> all communications between MPI processes if the tcp rpi is selected (which
> is the default). There are other rpi's which can be used for inter-process
> communication which include crtcp, lamd, sysv, usysv and gm. UDP is used
> for out of band communication. For more information, please see the user's
> documentation at www.lam-mpi.org/using/docs.
>
> Hope this helps,
> Anju
>
>
> On Thu, 17 Jun 2004, Muhlis Akdag wrote:
>
> > Hello
> >
> > I know there are many posts with the topic transport protocoll in lam
mpi...but here my question
> >
> > i read that lam mpi use udp to transport informations between
nodes...but i also read that a tcp socket create it from lambootagent...
> > so my question:
> >
> > what are transport with udp and what is transport with tcp...
> >
> > i test a code with 2 nodes...a send and a receive:
> >
> > #include <stdio.h>
> > #include <mpi.h>
> > #include <math.h>
> >
> > #define WORLD MPI_COMM_WORLD
> >
> > int main(int argc, char *argv[]){
> >
> > int rank, size, i;
> >
> > MPI_Init( &argc, &argv);
> > MPI_Comm_rank(MPI_COMM_WORLD, &rank);
> > MPI_Comm_size(MPI_COMM_WORLD, &size);
> >
> >
> > int l=1;
> > int sendarray[l];
> > int recvarray[l];
> >
> >
> >
> > if (rank==0){
> > for (i=0; i<l; i++){
> > sendarray[i] = i;
> > }
> > printf("proc %d: sendarray[%d] = %d\n", rank, l-1, sendarray[l-1]);
> >
> > MPI_Send( sendarray, l, MPI_INT, 1, 123, WORLD);
> > }
> > else if (rank==1){
> > MPI_Status status_recv;
> > MPI_Recv( recvarray, l, MPI_INT,0, 123, WORLD, &status_recv);
> >
> > printf("proc %d received : recvarray[%d] = %d\n", rank, l-1,
recvarray[l-1]);
> > }
> >
> > MPI_Finalize();
> >
> > return 0;
> > }
> >
> > than i trace ist with ethereal a network sniffer...i have many udp
packets between node a and b and also tcp packets...but what are transport
with what?
> >
> > a second question is...when use lam mpi ssh and rsh...is this right
when i say: only in lamboot to hboot the other nodes? with mpirun both
configuration are the same?
> >
> > i hope some people can help me and understand my confuse english :)
> >
> >
> >
> >
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