[reSIProcate] DNS SRV multiple records and timeouts

[Scott Godin]

Hi Nathan,

For Whitelisting - what do you mean about knowing all the hosts upfront?
I was referring to enabling the resip DNS Whitelisting feature - this
doesn't require knowing anything up front.

Records are greylisted so that they are tried after all other potentially
good records are tried - this way if the server happened to come back
oneline we will use it sooner than waiting for a blacklist entry to
timeout.

Scott


On Thu, Aug 15, 2013 at 1:34 PM, Nathan Stratton <nathan at robotics.net>wrote:

> On Thu, Aug 15, 2013 at 11:38 AM, Scott Godin <sgodin at sipspectrum.com>wrote:
>
>> Hi Nathan,
>>
>> As you mentioned grey listed items will only be tried when all other
>> non-blacklisted results are checked.  This means we will not try the grey
>> record first.  So new requests should be using the non-greylisted and
>> non-blacklisted entries.
>>
>> Some additional points:
>> 1.  Records are only greylisted for 32 seconds.  So after that time
>> expires, we could end up trying the potentially bad record again, and
>> repeating the greylist process.  Making the greylist time configurable
>> would be nice.
>> 2.  If you are creating a client and don't need to load balance your
>> outbound requests, then you could enable Whitelisting support - this enable
>> get your client to stick to a good record tree when one is found.  This is
>> disabled by default, since it breaks load balancing in SIP server
>> applications.  See  http://www.resiprocate.org/DNS for more info on how
>> to enable whitelisting (a compile time flag).
>>
>
> Yes, we could whitelist, but that would require knowing all the hosts
> upfront. We could have our gateway add timeouts to the blacklist, but as I
> was thinking about it I was just wondering why they were gray and not
> black. Why would you want to continue to try a host that you know will
> timeout?
>
> --
> ><>
> Nathan Stratton                                               Founder, CTO
> Exario Networks, Inc.
> nathan at robotics.net                                     nathan at
> exarionetworks.com
> http://www.robotics.net
> http://www.exarionetworks.com/
>
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