MATLAB DISTRIBUTED COMPUTING SERVER 4 - SYSTEM ADMINISTRATORS GUIDE Manuale Utente Scaricare il pdf (Pagina 47)

Troubleshoot Common Problems

Verify Multicast Communications

Note Multicast is required on the head node running the MATLAB job

scheduler (MJS) and on the client system, if you want to use the discover

cluster ca pa b ilities in Pa ra ll el Compu t in g Toolbox.

Multicast, unlike TCP/IP or UDP, is a s ubscription-based protocol where

a number of machines on a network indicate to the network their interest

in particular packets originating somewhere on that network. By contrast,

both UDP and TCP packets are always bound for a single machine, usually

indicated by its IP address.

The main tools for investigating this type of packet are:

•

tcpdump for UNIX operating systems

•

winpcap and ethereal for Microsoft Windows operating systems

• AJava

class included with the parallel computing products.

The Java class is called

com.mathworks.toolbox.distcomp.test.MulticastTester.Bothitsstatic

main method and its constructor take two input arguments: the multicast

group t o join and the port num ber to use.

This Java class has a number of simple methods to attempt to join a specified

multicast group. Once the class has successfully joined the group, it has

methods to send messages to the group, listen for me ssage s from the group,

and display what it receives. You can use this class both from a comm and-line

call to Java software and inside MATLAB.

From a shell prompt (assuming that

java is on your path), type

java -cp distcomp.jar com.mathworks.toolbox.distcom p.test.MulticastTester

You should see an output something like this:

0 : hos t1na me : 0

1 : host2name : 0

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MATLAB DISTRIBUTED COMPUTING SERVER 4 - SYSTEM ADMINISTRATORS GUIDE Manuale Utente Pagina 47