[jboss-jira] [JBoss JIRA] (JGRP-2023) Network unreachable with localhost addresses if -Djava.net.preferIPv4Stack=true isn't specified

[Richard Janík (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-2023?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13174700#comment-13174700 ] 

Richard Janík commented on JGRP-2023:
-------------------------------------

I have an update. After examining my routing tables with {{route -6}} and adding a new route for IPv6 localhost with {{sudo route -6 add ::1/0 dev lo}}, I was able to get rid of the error message. I still didn't manage to actually create a cluster when binding to localhost (IPv6). That makes sense though, since the only line in my routing table pertaining to the multicast address JGroups communicate on, is this:
{code}
Destination                    Next Hop                   Flag Met Ref Use If
ff00::/8                       [::]                       U    256 1  1133 enp0s25
{code}
Any attempt to add a similar route that sends messages to loopback interface, results in a route being added with "!" flag - which means the network is unreachable. I've added the multicast flag to my {{lo}} interface too: {{ifconfig lo multicast}}. I'm sure that there's something I don't know about IPv6 that's getting in the way.

I'd like to dig some more in it, but I don't think I'll be able to find much more time. Anyway, I now believe the problem is with my default configuration so I think this can be closed. Thanks.

> Network unreachable with localhost addresses if -Djava.net.preferIPv4Stack=true isn't specified
> -----------------------------------------------------------------------------------------------
>
>                 Key: JGRP-2023
>                 URL: https://issues.jboss.org/browse/JGRP-2023
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 3.6.7, 3.6.8
>         Environment: $ java -version
> java version "1.8.0_45"
> Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
> Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)
>            Reporter: Richard Janík
>            Assignee: Bela Ban
>
> When setting {{-bind_addr}} to localhost (either 127.0.0.1 or ::1) without specifying {{-Djava.net.preferIPv4Stack=true}}, JGroups fail to connect. The following errors are logged:
> {code}
> -------------------------------------------------------------------
> GMS: address=rjanik-24069, cluster=draw, physical address=0:0:0:0:0:0:0:1:37921
> -------------------------------------------------------------------
> Mar 03, 2016 11:41:12 AM org.jgroups.protocols.TP$BaseBundler sendSingleMessage
> SEVERE: JGRP000029: rjanik-24069: failed sending message to cluster (108 bytes): java.io.IOException: Network is unreachable, headers: PING: [type=GET_MBRS_REQ, cluster=draw], TP: [cluster_name=draw]
> ** View=[rjanik-24069|0] (1) [rjanik-24069]
> Mar 03, 2016 11:41:15 AM org.jgroups.protocols.TP$BaseBundler sendSingleMessage
> SEVERE: JGRP000029: rjanik-24069: failed sending message to cluster (56 bytes): java.io.IOException: Network is unreachable, headers: NAKACK2: [MSG, seqno=1], TP: [cluster_name=draw]
> {code}
> I'm not sure if there's some other configuration option that I forgot to add, but the example (in Steps to Reproduce) works with previous versions (3.6.6 for example), so I assume not.



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