[asterisk-ss7] How Asterisk + sigtran ?

[Jan Berger]

hi Amish

< snip >

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,

Amish


< snip>

Yes you loose out on performance using TCP rather than SCTP, but it should work ok on small-scale implementations where performance is not critical. However - SCTP was designed to solve some of the issues with signalling over TCP.

Jan



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
distributed
system where it is possible to separate the signaling and network
connections
(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
(Dialogic
Distributed Signaling Interface or DSI) do not allow this.  The various
SS7
components that make up SIGTRAN/ISUP operate as separate processes
communicating
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
single
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
Asterisk
systems that have registered with the server.  The Asterisk system who
replies
first (presumably the least busy system) will be granted the call.  We
think
this is a reasonable way of call distribution.
   
  John
Hermanski
  Technical
Marketing
Engineer
  

  Dialogic Inc.

  5
Monroe St.
  Salem,
MA

  USA

  

Tel:       978
744
9098

  Cell:     
  978
836 8028

  Email:  
  john.hermanski at dialogic.com
  Web:   
  www.dialogic.com
   
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