[jboss-jira] [JBoss JIRA] Commented: (JGRP-961) Tests passing under IPv4 but failing under IPv6 in JGroups 2.4.5

[Richard Achmatowicz (JIRA)]

    [ https://jira.jboss.org/jira/browse/JGRP-961?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12466806#action_12466806 ] 

Richard Achmatowicz commented on JGRP-961:
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This was traced to a problem specific to IPv6: using link-local IPv6 addresses with no zone id specified.

Link-local addresses are non-global addresses in IPv6; they are identified by the prefixes fe80::/10 . When IPv6 is enabled on a host, link-local addresses are assigned automatically by the OS.
For example, fe80::215:58ff:fec8:81a8 is a link-local address.

When sending a message to a link-local address from a multi-homed machine, the  address must be qualified by the zone id - effectively the name of the interface you want the message to go out on. This is because the same link-local address may be defined on two or more network segments attached to the host, and it becomes ambiguous which network segment is desired. The new address is a scoped link-local address and has the form <link-local addr>%<scope id> where scope id is the name of the interface or its numerical representation.

So, for example,  fe80::215:58ff:fec8:81a8%eth0 is the scoped address for the link-local address fe80::215:58ff:fec8:81a8. The zone id indicates we want to send the message via the eth0 interface. 

If the zone id is omitted, the OS will assign a default interface, which may not be the one you want.

The problem I was having was using a link-local address as a bind address, but not specifying the zone id. A default zone id was being supplied by the OS and my messages were being sent on the wrong interface.

> Tests passing under IPv4 but failing under IPv6 in JGroups 2.4.5
> ----------------------------------------------------------------
>
>                 Key: JGRP-961
>                 URL: https://jira.jboss.org/jira/browse/JGRP-961
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 2.4.5
>         Environment: Fedora 9, JDK 1.4.2, JDK 1.5.0 
>            Reporter: Richard Achmatowicz
>            Assignee: Richard Achmatowicz
>            Priority: Minor
>             Fix For: 2.4.6
>
>         Attachments: ServerSocketReceiver.java, ServerSocketSender.java
>
>
> When running the JGroups testsuite against IPv6 addresses (as opposed to IPv4 addresses), some tests pass on IPv4 but fail on IPv6.
> This is an issue as IPv6 compatability is quickly becoming an important issue for EAP.

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