Dear rhn-engineering-bban and sdouglas1@redhat.com, I encountered problems with UDP multicast on IPv6, intimately related to my earlier report on UNDERTOW-454.

Facts

• all servers bound to global scope IPv6 address 2620:52:0:105f::ffff:0
• test runs on a single box, on a one NIC
• pure IPv6 RHEL6 x86_64, i.e. no IPv4 interfaces configured (not even localhost)

Configurations

UDP multicast config matrix

• GLOBAL = global scope UDP multicast, starts with ff0e::*
• NETWORK_LOCAL = local network nodes UDP multicast, starts with ff02::*
• INTERFACE_LOCAL = interface local UDP multicast, starts with ff01::*

EAP 6.4.0 and EAP 7.0.0.DR13 config

• EAP 7.0.0.DR13 acts both as worker and balancer, depending on the configuration; see Section Results below

Interfaces

The same for all the test runs:

<interface name="management">
<inet-address value="2620:52:0:105f::ffff:0"/>
</interface>
<interface name="public">
<inet-address value="2620:52:0:105f::ffff:0"/>
</interface>

UDP multicast config matrix

• GLOBAL

  <socket-binding name="jgroups-mping" port="0" multicast-address="ff0e::12" multicast-port="45700"/>
  <socket-binding name="jgroups-udp" port="55200" multicast-address="ff0e::12" multicast-port="45688"/>
  <socket-binding name="modcluster" port="0" multicast-address="ff0e::a" multicast-port="35432"/>
  

• NETWORK_LOCAL

  <socket-binding name="jgroups-mping" port="0" multicast-address="ff02::0" multicast-port="45700"/>
  <socket-binding name="jgroups-udp" port="55200" multicast-address="ff02::0" multicast-port="45688"/>
  <socket-binding name="modcluster" port="0" multicast-address="ff02::a" multicast-port="35432"/>
  

• INTERFACE_LOCAL

  <socket-binding name="jgroups-mping" port="0" multicast-address="ff01::14" multicast-port="45700"/>
  <socket-binding name="jgroups-udp" port="55200" multicast-address="ff01::14" multicast-port="45688"/>
  <socket-binding name="modcluster" port="0" multicast-address="ff01::a" multicast-port="35432"/>
  

Apache HTTP Server config

• either from JWS 3.0.2-ER1 or EWS 2.1.0
• Listen [2620:52:0:105f::ffff:0]:8847
• GLOBAL AdvertiseGroup [ff0e::a]:35432
• NETWORK_LOCAL AdvertiseGroup [ff02::a]:35432
• INTERFACE_LOCAL AdvertiseGroup [ff01::a]:35432

Results

UDP Multicast	Workers	Balancer	Result	Comment
GLOBAL	EAP 6.4.0	EWS 2.1.0		No comment.
NETWORK_LOCAL	EAP 6.4.0	EWS 2.1.0		harmless SocketException
INTERFACE_LOCAL	EAP 6.4.0	EWS 2.1.0		No comment.
GLOBAL	EAP 7.0.0.DR13	JWS 3.0.2-ER1		No comment.
NETWORK_LOCAL	EAP 7.0.0.DR13	JWS 3.0.2-ER1		JGroups don't start MSC000001
INTERFACE_LOCAL	EAP 7.0.0.DR13	JWS 3.0.2-ER1		No comment.
GLOBAL	EAP 7.0.0.DR13	Undertow 1.3.3.Final		No exceptions; balancer advertising doesn't work
NETWORK_LOCAL	EAP 7.0.0.DR13	Undertow 1.3.3.Final		JGroups don't start MSC000001
INTERFACE_LOCAL	EAP 7.0.0.DR13	Undertow 1.3.3.Final		No exceptions; balancer advertising doesn't work

Regarding "advertising doesn't work"

The EAP 7.0.0.DR13 Undertow 1.3.3.Final balancer seems to be working, according to the log:

INFO  [io.undertow] (MSC service thread 1-1) UT005039: Undertow starts mod_cluster proxy advertisements on /ff0e:0:0:0:0:0:0:a:35432 with frequency 10000 ms
...snip...
09:37:53,018 DEBUG [io.undertow] (default I/O-1) UT005040: Gonna send payload:
HTTP/1.0 200 OK
Date: Thu, 5 Nov 2015 09:37:53 -0500
Sequence: 1
Digest: 70074bf470f252362639a18364e27a45
Server: 2b0c7b3b-3869-41f4-bcfc-923da9f774a9
X-Manager-Address: 2620:52:0:105f:0:0:ffff:0%eth0:8484
X-Manager-Url: /
X-Manager-Protocol: http
X-Manager-Host: 2620:52:0:105f:0:0:ffff:0%eth0

Workers also seem to be in order, up and running:

INFO  [org.jboss.modcluster] (ServerService Thread Pool -- 65) MODCLUSTER000032: Listening to proxy advertisements on /ff0e:0:0:0:0:0:0:a:35432

None of the workers ever replies to the balacner though. Any suggestions, sdouglas1@redhat.com?

Please, share your view on the topic. Thanks guys.