perfSONAR User Q&A and Other Discussion

[Eli Dart <>]

Hi Brian,

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.  I expect that it's unlikely to change.  It certainly causes problems for test and measurement in multi-address-family environments - we have struggled with this at ESnet as well. We currently have a separate name for the IPv6 address for most of our testers (e.g. bost-pt1.es.net vs. bost-pt1-v6.es.net).  One exception to that is sacr-pt1.es.net (it helps to have a dual-stack host around to see what the behavior of a dual-stack host is).

Thanks,

Eli

On Thu, May 5, 2016 at 9:28 AM, Brian Candler <> wrote:

When I have a maddash mesh which includes hostX.example.com and hostY.example.com, and there are only A records for those names, it runs tests over V4 fine.

But when the names have both A and AAAA records, the tests only run on IPv6; the IPv4 tests stop. This is seen from looking at the collected graphs at the /toolkit/ home page. The v4->v4 and v6->v6 graphs are both listed, but the v4->v4 data stops at the time the AAAA records were added.

(I do realise that the dashboard itself is going to have difficulty rendering a single traffic light where there are multiple data sources, so perhaps that's the underlying cause of this behaviour)

So my question is: is running a maddash where the same hostname has both A and AAAA records not supported? Does this mean I need to create separate v4 and v6 hostnames, *and* create two separate meshes (i.e. one between the v4 interfaces and one between the v6 interfaces?)  Or is this likely to be allowed in future?

I can give some sample URLs off-list if required.

Regards,

Brian Candler.

P.S. Running latest perfsonar; these boxes auto-updated to 3.5.1

--

Eli Dart, Network Engineer                          NOC: (510) 486-7600

ESnet Office of the CTO (AS293)                          (800) 333-7638

Lawrence Berkeley National Laboratory 

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