Re: CIC as a RK

Tolga,

There are already statements that we placed in RFC 4666 (and 3332 before it):

This:

   For carrier grade networks, the failure or isolation of a particular
   signalling process should not cause stable calls or transactions to
   be lost.  This implies that signalling processes need, in some cases,
   to share the call/transaction state or be able to pass the call state
   information between each other.  In the case of ASPs performing call
   processing, coordination may also be required with the related Media
   Gateway to transfer the MGC control for a particular trunk
   termination.  However, this sharing or communication of
   call/transaction state information is outside the scope of this
   document.

which clearly scopes out issues within the MGC complex for sharing state
information between ASPs.

And, this:

   In the process of failover, it is recommended that, in the case of
   ASPs supporting call processing, stable calls do not fail.  It is
   possible that calls in "transition" may fail, although measures of
   communication between the ASPs involved can be used to mitigate this.

   For example, the two ASPs may share call state via shared memory, or
   may use an ASP to ASP protocol to pass call state information.  Any
   ASP-to-ASP protocol to support this function is outside the scope of
   this document.

Which also scopes it out.

For load sharing there is this:

   In the case of a Loadshare mode AS, receipt of an ASP Active message
   at an SGP or IPSP causes direction of traffic to the ASP sending the
   ASP Active message, in addition to all the other ASPs that are
   currently active in the AS.  The algorithm at the SGP for loadsharing
   traffic within an AS to all the active ASPs is implementation
   dependent.  The algorithm could, for example, be round-robin or based
   on information in the Data message (e.g., the SLS, SCCP SSN, or ISUP
   CIC value).  ...

As the loadsharing algorithm is implementation dependent (at the SGP) and
there is no protocol mechanism for determining what that algorithm may be,
the ASP in a loadshare AS must be prepared to handle any range of traffic
for the AS.

These principles for loadsharing and ASP state sharing have been present
in M3UA from the start.  Altering them would represent a significant change
to the document (and to loadsharing implementations).  Procedures for
backward compatibility (such as those provided by LOADSEL) would be
necessary.

--brian


Tolga Asveren wrote:                                                 (Thu, 09 Nov 2006 13:18:49)
> IMO, allowing CIC ranges as RK constructs and explaining how it is supposed
> to be used and addressing any issues related with it (hopefully not much) in
> the M3UA document may be useful.
> 
>     Thanks,
>     Tolga
> 

-- 
Brian F. G. Bidulock
[email protected]
http://www.openss7.org/