Subject: RE: [Sigtran] Question related with DAUD Message

From: "Colmenares, Oscar (Oscar)" <[email-masked]>
Date: Wed, 31 Jan 2007 10:02:59 -0700

Andrew

	My concern here is that is multiple ASP and SG providers are having
their own interpretation to the standard and we can have inter-operability
problems in the future.

	So far we as an ASP we are trying to implement multiple point codes
in the same DAUD message and we can support up to 1024 point codes but the
SG interpretation was to set a limit in the numbers of point codes per DAUD
message up to 16, so we are facing some developments problems due different
interpretations.

	I think it will be a good idea to have a recommendation from the
Sigtran expert as how this should work in order to align all the ASP and SG
and define a way to use this kind of message.

	So my answer here will be, this help but not enough due there is no
way to decide who is right or wrong performing this setting in the message.

	Please if you or your team have recomendations in how to set this
(something official) please let us know, because this is very important for
us.

Regards

Oscar

-----Original Message-----
From: Andrew Booth [mailto:[email-masked]]
Sent: Miércoles, 31 de Enero de 2007 12:18 p.m.
To: Colmenares, Oscar (Oscar)
Cc: [email-masked]
Subject: Re: [Sigtran] Question related with DAUD Message

I think the ASP can send DAUD in any way it sees fit, according to the RFC.

The following comments are my own and are not specified in the RFC.

I think assuming that state is always synchronized is a dangerous
assumption.  For instance, what if the SG is in overload and discards a
DAVA?  What if there's a bug on one end or the other?  What if the ASP
is connected to two SGPs and receives DUNA + DAVA from SGP1 and DUNA +
association loss from SGP2, in that order?
The main risk would probably be a missing DAVA, since a missing DUNA
would get discovered by a response DUNA if traffic is sent to the
destination.

>From an operational standpoint I'd be careful sending DAUD with a big
wildcard, since it's difficult to estimate how many responses you might
get and how fast, so it's hard to avoid potential overloads.  Also, you
won't necessarily know when you have all the responses (if you care).

Other than that, it's more bandwidth efficient to send multiple affected
PCs in one message, but that's only a concern if you're running over
bandwidth constrained networks or auditing many PCs.  So, take your pick.

Does that help?
Andrew

Colmenares, Oscar (Oscar) wrote:
> Sigtran Experts
>
> 	I was looking for some help related with how to set the DAUD
> message, I was reading some message from HS Jang related when the ASP need
> to use the DAUD message, explain as follow
>
> Let me summarize about DAUD in SUA ASP with your postings and my
> understanding. first of all,
>  1) ASP does not need to send DAUD in normal situation. because SCCP in SG
> cares it with its mechanism and inform the ASP of the changes in DPC/SSN
> with SSNM message. i.e. the state information about destinations are
> synchronized all the time.
>  2) the only time ASP needs to send DAUD is when the ASP is recovered from
> isolation because ASP has no state information about destinations now. (
but
> this is also not necessary for normal operation of data transfer. it is
only
> necessary when ASP really wants to know the state information of
> destinations for example, in the respect of OAM or something ) 
> 3) there are mentions about sending DAUD periodically in RFC but it is
> somewhat wrong. 
> 	
> 	Now base on these explanation and related with point 2, send DAUD
> message when the ASP is recovered from isolation, my question is there is
> any rules in other to how to send these point codes?? do we have or must
> send multiple messages with one point code information per message, or
send
> just one message with all the point codes information???
>
> 	The main idea here is understand if I have a system with multiple
> point codes, for example 25 point codes, how the standard said we need to
> send the DAUD message, just one message with all the point codes inside or
> 25 single messages with just one point code per message.
>
> I really appreciate your help on this question
>
> Best regards
>
> Oscar
>
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>   

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From: "Ankit Kumar Sharma" <[email-masked]>
Date: Wed, 31 Jan 2007 17:15:24 +0000

I have also faced this problem in past. Some stack vendors limit it on no.
of point codes in DAUD message and some on the length of DAUD message(DAUD
message greater than xx limit would get discarded).
If I am not wrong then as per RFC, there isn't any limit on number of Point
codes in DAUD. If any vendor is not following this then its a bug in their
stack.
I think there should be some upper limit set on number of Point codes in
DAUD for better interworking.

cheers,
Ankit