[jboss-jira] [JBoss JIRA] Commented: (JGRP-515) UDP.java requires the multicast address in the multicastsocket constructor to fix crosstalk on certain operating systems

[Bela Ban (JIRA)]

    [ http://jira.jboss.com/jira/browse/JGRP-515?page=comments#action_12362462 ] 
            
Bela Ban commented on JGRP-515:
-------------------------------

[Regarding my comment on May 17 11:02am]

We currently use the wildcard address for receiving IP multicasting packets, so the socket bound to 45566 is 0.0.0.0:45566. This is the same as receive_on_all_interfaces, as traffic will be received on *any* NIC. 

MulticastSocket.set(Network)Interface() is only used for *sending* packets.

So, at one point, we need to decide whether to discard receive_on_all_interfaces, or whether to really bind to the interface defined by bind_addr. The down side of the latter is that we might have more cases where members don't find each other because they bind to different NICs.

In any case: even if we receive IP multicast traffic on *all* interfaces, the different multicast (class D) addresses should discard traffic sent to 228.0.0.2:50000 but we are listening on 228.0.0.1:50000 ! This is a bug, as described below:
Yes, Aleksander Kostadinov wrote a C test that shows it; you can see it 
on https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=231899.

Just to clarify; this problem does exist on Linux (not just Red Hat; we 
saw it on SuSE as well).  We don't see it on Windows XP and Solaris. If 
you want to test your OS you can have a look at the C test attached to 
the above bugzilla, or use the Java-based test attached to 
http://wiki.jboss.org/wiki/Wiki.jsp?page=PromiscuousTraffic.

> UDP.java requires the multicast address in the multicastsocket constructor to fix crosstalk on certain operating systems
> ------------------------------------------------------------------------------------------------------------------------
>
>                 Key: JGRP-515
>                 URL: http://jira.jboss.com/jira/browse/JGRP-515
>             Project: JGroups
>          Issue Type: Patch
>         Environment: Tested on Fedora Core 6, JDK 1.5.0_10
>            Reporter: ggimler
>         Assigned To: Bela Ban
>             Fix For: 2.5
>
>         Attachments: UDP.java
>
>
> I'm submitting a patch for a crosstalk issue described below.
> I'm trying to debug a problem I'm seeing when running JGroups on the
> same network/machine as another application that is sending/receiving
> data via regular multicast (not through JGroups).  I'm using version
> 2.4.1-SP3.  My scenario is as follows...
> JGroups send on 228.0.0.1:50000
> JGroups receive on 228.0.0.1:50000
> This works fine.  When I start up another application that does
> Sends regular multicast on 228.0.0.2:50000
> Receives regular multicast on 228.0.0.2:50000
> Then the JVM with the JGroups sender/receiver complains with:
> May 15, 2007 4:47:59 PM org.jgroups.protocols.TP handleIncomingPacket
> WARNING: packet from 192.168.101.133:36594 has different version
> (26725) from ours (2.4.1). Packet is discarded
> The patch is in UDP.java:

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