mcast_group_addr is not taking the input value

[cyanaryan]

I am working on upgrading the jgroup to 4.x version. So while updating the configuration file I am currently doing this

<config xmlns="urn:org:jgroups"
        xmlns:xsi="[http://www.w3.org/2001/XMLSchema-instance"](http://www.w3.org/2001/XMLSchema-instance%22)
        xsi:schemaLocation="urn:org:jgroups [http://www.jgroups.org/schema/jgroups-4.2.xsd"](http://www.jgroups.org/schema/jgroups-4.2.xsd%22)>
   <UDP
         mcast_addr="${cluster.udp.mcast_addr:FF05::2592}"
         mcast_port="${cluster.udp.mcast_port:46654}"
         tos="8"
         ucast_recv_buf_size="20000000"
         ucast_send_buf_size="640000"
         mcast_recv_buf_size="25000000"
         mcast_send_buf_size="640000"
         max_bundle_size="64000"
         ip_ttl="${jgroups.udp.ip_ttl:2}"
         enable_diagnostics="false"
 
         thread_naming_pattern="pl"
 
         thread_pool.enabled="true"
         thread_pool.min_threads="2"
         thread_pool.max_threads="30"
         thread_pool.keep_alive_time="20000"
         />
 
   <PING/>
   <MERGE3 max_interval="30000" min_interval="10000"/>
   <FD_SOCK/>
   <FD_ALL/>
   <BARRIER flush_timeout="30000" />
   <pbcast.NAKACK2   
                  xmit_table_max_compaction_time="30000"             
                   use_mcast_xmit="true"                 
                   discard_delivered_msgs="true"/>
   <UNICAST3 conn_close_timeout="0"/>
   <pbcast.STABLE stability_delay="1000" desired_avg_gossip="50000" max_bytes="1000000"/>
   <pbcast.GMS print_local_addr="false" join_timeout="3000" view_bundling="true"/>
   <UFC max_credits="500000" min_threshold="0.20"/>
   <MFC max_credits="500000" min_threshold="0.20"/>
   <FRAG2 frag_size="60000"  />
   <!-- <pbcast.STREAMING_STATE_TRANSFER/> -->
   <pbcast.FLUSH timeout="0"/>
   <pbcast.STATE_SOCK pool_thread_keep_alive="30000"/>
</config>

Currently, the value in the mcast_group_addr it's taking 228.8.8.8 and not the ff05. In the previous version I was getting the ff05 address. Can u please specify, why is that so? Can u please help me on how to correct that.

Previous version: 2.x
Previous mcast_group_addr=/ff05:0:0:0:0:0:0:4

[belaban]

I'll take a look. It might be incorrectly parsed because of the multiple colons (::) present in the IPv6 address...

[rhusar]

In case this is really parsed incorrectly (the correct parsing IIUC should be find first colon and everything before is the expression and everything after is the value) you can workaround as:

1. remove the expression and just put in the value i.e. mcast_addr="FF05::2592"
2. remove the value and pass it via system property - i.e. mcast_addr="${cluster.udp.mcast_addr}" and start process with -Dcluster.udp.mcast_addr=FF05::2592

[cyanaryan]

@rhusar
I am using the first approach mcast_addr="FF05::2592" .Still it is taking the default value 228.8.8.8

[belaban]

The reason mcast_addr is not used is that you're using an IPv4 stack: since bind_addr is null and -Djava.net.preferIPv6Addresses=true is not set, JGroups prefers IPv4 addresses. This means that the value of mcast_addr is ignored [1].

You can change this by either setting -Djava.net.preferIPv4Stack=false -Djava.net.preferIPv6Addresses=true or by setting bind_addr in the configuration file to an IPv6 value.

[1] http://www.jgroups.org/manual5/index.html#IPAddresses

[belaban]

The parsing is actually correct