[ovs-dev] DNS support feature (was: Re: DNS support options)

Yifeng Sun pkusunyifeng at gmail.com
Wed Oct 25 21:16:28 UTC 2017

I feel that unbound stands out in the available open source DNS resolver.

Below is the summary for unbound:
* The actual resolving work is done by a background process or thread. A
background process or thread seems unavoidable. Linux's getaddrinfo_a
clones a thread similarly.
* It is ported on Linux, BSD, Windows, MacOS/X and Solaris/SPARC. This is
good because OVS runs on a large range of platforms.
* It complies to the standard, with optional DNSSEC support. Some of its
features may not be needed in our case.
* The unbound context is thread-safe. Its internal locks may bring some
overhead. But since the DNS resolving is not frequent in OVS, I suppose
this small overhead is not an issue.

Unbound looks like a good option. Another option is to create a background
thread which processes DNS resolving requests from the main thread and
sends back the resulting events to the main thread. This method is quite
simple and straightforward.

The above are what I got so far. Please give your thoughts, thanks a lot.

Below is the link for original discussion:

On Wed, Oct 25, 2017 at 2:11 PM, Ben Pfaff <blp at ovn.org> wrote:

> Hello everyone, please allow me to introduce Yifeng Sun (CCed), who
> recently joined VMware's Open vSwitch team.  I've asked Yifeng to start
> out by working on DNS support for Open vSwitch.  Yifeng, can you tell us
> about what you've discovered so far, based on this thread from August
> that I'm reviving, and your tentative conclusions?
> Thanks,
> Ben.

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