[asterisk-ss7] How Asterisk + sigtran ?

Jan Berger janvb at live.com
Tue Feb 9 07:13:38 CST 2010


All Dialogic needs to do is to provide a standard M3UA through SCTP ( or even TCP) - and if you do the same, regardless of vendor  on Asterisk it should work - assuming both following the standard. But, to me it sounds like this is a very propritary solution ???

As for Asterisk I clearly remember a M3UA in LGPL some years ago, but I have not seen the code for it lately. But, you are GPL so you can canibilize from OpenSS7.

If not I can provide source code in C for M2UA/M3UA in GPL compatible license assuming someone can assist on the Astrisk implementation. This is however work in progress, so it will take some time before it's ready.


Date: Mon, 8 Feb 2010 23:04:56 +0200
From: amish at 3g.co.za
To: asterisk-ss7 at lists.digium.com
Subject: Re: [asterisk-ss7] How Asterisk + sigtran ?


Hi John,

Routing contexts and keys were discussed at length on the IETF's
SIGTRAN mailing list, when M3UA was developed. You can look at the
benefits of this approach in the mailing list archives.

Anyway, would it not be possible for you to provide a M3UA
implementation for Asterisk (even if it is in binary format to protect
your proprietary code)? This would have the advantage of not requiring
us to maintain an additional Diastar server (a potential point of
failure). With the Diastar server, I would also need to purchase more
Diastar servers as my capacity/redundancy requirements increase (in
addition to increasing the asterisk capacity in the backend). 

M3UA would provide the benefit of multiple distributed asterisk boxes
that can be added or removed on the fly from their connectivity to the
signalling gateway. With M3UA we would also get the of from using SCTP
in the distributed architecture, with its support for multi-homing,
multiple streams, etc. features.

With Diastar we use SIGTRAN over SCTP towards the PSTN. Do we not loose
all the SCTP benefits by now using TCP from Diastar to Asterisk? As an
example, SCTP reduces head-of-line blocking while using TCP from
Diastar to Asterisk reintroduces head-on-line blocking.

Best Regards,


On 02/08/2010 09:55 PM, John Hermanski wrote:


  Hi Amish,
  The main advantage of the
client/server relation ship between
the DiaStar server and the Asterisk client is to be able to provide a
system where it is possible to separate the signaling and network
(DiaStar) from the application services.  (Asterisk)   This is an
advantage for
larger systems.  Multiple standard, easily built Asterisk boxes can
added or
removed on the fly without any adjustments to DiaStar.  There’s a clean
separation between the application and network connectivity.
  While, as you point out,
it may be possible to be more
efficient by moving M3UA to the Asterisk systems, our base SS7 products
Distributed Signaling Interface or DSI) do not allow this.  The various
components that make up SIGTRAN/ISUP operate as separate processes
by means of Unix message queues. They are controlled by a master
process that reads
the SS7 configuration and then starts up the needed stacks on the
system.  DiaStar uses DSI, so we have to live within its constraints.
  So, rather than dividing
work load based on routing contexts
or keys, call distribution to multiple Asterisk systems is done by
means of a “who’s
least busy and replies first” to the server’s request for someone
to handle an inbound call.  A “Hello” message is sent from DiaStar,
via Woomera, (the protocol used between Asterisk and DiaStar)  to all
systems that have registered with the server.  The Asterisk system who
first (presumably the least busy system) will be granted the call.  We
this is a reasonable way of call distribution.

  Dialogic Inc.

Monroe St.



Tel:       978

836 8028

  john.hermanski at dialogic.com
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