perfSONAR User Q&A and Other Discussion

[Brian Candler <>]

On 05/05/2016 18:33, Andrew Lake wrote:

If you do not specify those options, then the underlying tool is going to always prefer IPv6 if both endpoints in the test have v6 addresses, otherwise it will fall back to IPv4. MaDDash in that case will just ask for any result, not caring if its v4 or v6, and display/alert on whatever it gets back. It sounds like this behavior is what you are running into, so creating a couple of tests with ipv4_only and ipv6_only should get the desired result.

OK: creating two meshes with ipv4_only and ipv6_only should do it, I'll give that a go. Thank you.

Eli Dart wrote:

> In general, if there is an A record and a AAAA record for the same name, host stacks prefer IPv6.

>

> My understanding is that this is intended to facilitate the transition from IPv4 to IPv6.

>

> This is host-level behavior.

This may be true in general; however it's not true of manually-configured tests in perfsonar, where you can select to use ipv4, ipv6, or both:



Hence it was surprising (to me) that maddash behaved differently.

For tests which I've manually configured in the GUI with both IPv4 and IPv6 checked, they appear like this in regular_testing.conf:

<test>
    <parameters>
        packet_length   180
        test_ipv4_ipv6   1
        type   powstream
    </parameters>
    target   xxx.example.com
    description   POP to POP
    <schedule>
        type   streaming
    </schedule>
</test>

which indeed is documented here:
http://docs.perfsonar.net/config_regular_testing.html#test-ipv4-ipv6-directive

Whereas maddash is different, and instead has "ipv4_only" and "ipv6_only" options:
http://docs.perfsonar.net/config_mesh.html#ipv4-only-directive

I didn't find documented what happens if you omit both.

Regards,

Brian.