Re: [Sigtran] M3UA: Synchronizing DPC availability state between ASPs in the same AS

Dan Gora <dan.gora@gmail.com> Mon, 10 April 2017 20:00 UTC

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From: Dan Gora <dan.gora@gmail.com>
Date: Mon, 10 Apr 2017 17:00:12 -0300
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To: bidulock@openss7.com, Dan Gora <dan.gora@gmail.com>, sigtran@ietf.org
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Subject: Re: [Sigtran] M3UA: Synchronizing DPC availability state between ASPs in the same AS
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On Mon, Apr 10, 2017 at 4:51 PM, Brian F. G. Bidulock
<bidulock@openss7.com> wrote:
> Dan,
>
> Brian F. G. Bidulock wrote:       (Mon, 10 Apr 2017 13:41:19)
>>
>> So, yes and no, you may have to correlate the receipt of
>> DUNA, DAVA, DRST, SCON at any ASP across all ASPs active
>> for the AS (if the SG does not broadcast); however, you
>> should never have to do so in response to DAUD.
>>
>
> See, for example, RFC 4666/5.4 Auditing Examples.  You
> will see that all transactions are between ASP and SGP,
> not between AS and SG.

Right... This is what led me to believe that we didn't have to
synchronize the DPC states (and various conversions on the mailing
list), but then again your description of considering ASPs in the same
AS connected to the same SG as links in a linkset is what made be
think that yes, we do need to synchronize the DPC states.

However, this customer's SG seems to be even worse in that it's
replying to a DAUD from ASP2 with a DAVA/DUNA to ASP1, _not_ ASP2 (or
so they say, we still haven't been provided with traces or debug logs
yet..).  That just seems broken to me..

If we have to "fix" this, it seems like it should be safe to
synchronize the states across all the active ASPs.  I cannot think of
a scenario where a DPC would be available in ASP 1 via SG1, but not
via ASP2 as long as both are connected and ASP-Active with the SG1
since the SG1 has to synchronize it's state among all the SGPs in the
SG.  Right?

thanks
dan