[jboss-jira] [JBoss JIRA] (JGRP-1808) Mac OS: no multicast route for 127.0.0.1

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12983955#comment-12983955 ] 

Bela Ban commented on JGRP-1808:
--------------------------------

This started to occur when sending of a multicast packet was changed from using the MulticastSocket {{mcast_sock}} to using the DatagramSocket {{sock}} in {{UDP}}. 
This change was needed so that receivers can identify the sender's IP address: if sent via mcast_sock, the address might be {{228.8.8.8:45566}}, but if sent via {{sock}} it would be something like {{192.168.1.5:34526}}, which identifies the sender's IP address and port.
This is needed e.g. to discard _multicast messages_ sent by self at the transport, without having to de-serialize the message.

> Mac OS: no multicast route for 127.0.0.1
> ----------------------------------------
>
>                 Key: JGRP-1808
>                 URL: https://issues.jboss.org/browse/JGRP-1808
>             Project: JGroups
>          Issue Type: Task
>      Security Level: Public(Everyone can see) 
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>            Priority: Minor
>             Fix For: 3.5
>
>
> On Mac OS (Mavericks), there is no multicast route in the routing table. So the default route is used (say 192.168.1.1). However, this doesn't work for nodes bound to 127.0.0.1 (don't know why).
> So for loopback, an mcast route has to be added, e.g.
> {noformat}
> sudo route add -net 224.0.0.0/4 127.0.0.1
> {noformat}
> This adds a default route to all class D (multicast) addresses via loopback. However, this doesn't work if the node is bound to 192.168.1.x !
> TODO:
> * See if we can get a default multicast route through 192.168.1.1 and make nodes bound to 127.0.0.1 use it
> * If this doesn't work, define multiple mcast routes for different mcast addresses, e.g.
> {noformat}
> sudo route add -net 224.0.0.0/4 127.0.0.1
> sudo route add -net 230.0.0.0/8 192.168.1.0
> {noformat}
> This adds loopback as default mcast route, but uses en0 if a multicast address starts with 230.x.x.x.



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