Subject: Can Traffic Mode be Dynamic?

From: Jacques Rajchgod <[email-masked]>
Date: Thu, 15 Nov 2001 10:34:47 -0600

A question has arisen during our test cycle of M3UA, that probably applies
to all "UA's":

Traffic mode assignment is done at ACT time. The mode is specified as a
param attached to the ACT message:
ASPACT(LdShr). Please, kindly advise:

My impression is, that traffic mode defaults at init time to "LdShr". This
allows all ASPs to traffic as needed.Then:
When an ASP determines that a sudden pressure exists at its bearers (the
MGW), it ACTs with an OVERRIDE request to monopolize all traffic resources
thereafter, until pressure at its bearers has subsided. Then, once the
pressure has subsided, the OVERRIDING ASP is supposed to revert to normal
traffic mode so as to allow other ASPs to traffic...

How would an ASP request "bandwidth" dynamically - would it perform as
follows?

1) ACTs as LdShr at Init time.
2) Detects pressure at bearers, then generates ASPIA to get out of LdShr.
3) Generates ACT(Override) to re-enter traffic as lone trafficker to handle
its sudden pressure.
4) Everybody is out except the overrider.
5) Pressure has subsided.The Overrider detects that traffic no longer
requires a lot of "bandwidth".
6) It generates ASPIA to get out of OVERRIDE so to allow other ASPs to begin
trafficking.
7) It generates ACT(LdShr) to get out of OVERRIDE.

Is this how an ASP would do it? Or would an ASP sends ACT's(Traffic_mode=x)
w/o "logging-out"?
Is this the way "Bandwidth-on-demand" would work at an ASP?

Thanks,

Jacques Rajchgod
MCI Worldcom
Next Generation System Evaluation
Tel: [972] 729-7180
E-mail: [email-masked]

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From: Mark Davidson <[email-masked]>
Date: Thu, 15 Nov 2001 16:21:40 -0500

My understanding of override mode is that it is used for handling connections to
active/standby
equipment (e.g. MGC) and allows the active portion of the equipment to direct
traffic towards itself.
In the case of a failover (active MGC fails) the standby becomes active and
sends ASPACT(OVERRIDE).

The M3UA draft does not allow changing between override and standby traffic
modes, since it requires an
error message when a mode different from the currently configured one is
received:

   from 4.3.4.4 ...
   If the SGP determines that the mode indicated in an ASP Active
   message is unsupported or incompatible with the mode currently
   configured for the AS, the SGP responds with an Error message
   ("Unsupported / Invalid Traffic Handling Mode").

Thus you cannot dynamically change between traffic modes.

As for default mode, the draft states

   If the traffic handling mode of the Application Server is not already known
   via
   configuration data, then the traffic handling mode indicated in the
   first ASP Active message causing the transition of the Application
   Server state to AS-ACTIVE MAY be used to set the mode.

It doesn't give any means for dynamically changing the mode.

One of our concerns is when there is too much traffic for a single ASP to
handle, but
we want to use an active/standby configuration.  I.e., need override mode, but
need to switch
between sets of ASPs rather than single ASPs. Suggestions?

-Mark Davidson
[email-masked]

Jacques Rajchgod <[email-masked]> on 11/15/2001 11:34:47 AM

Please respond to [email-masked]

To:   "sigtran" <[email-masked]>
cc:    (bcc: Mark Davidson/Raleigh/TEKELEC)
Subject:  Can Traffic Mode be Dynamic?

Thanks,

Jacques Rajchgod
MCI Worldcom

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 15 Nov 2001 16:09:17 -0600

Mark,

Several comments...

Standby mode has been removed from the draft.

Mark Davidson wrote:                                         (Thu, 15 Nov 2001 16:21:40)
> 
> My understanding of override mode is that it is used for handling
> connections to active/standby equipment (e.g. MGC) and allows the
> active portion of the equipment to direct traffic towards itself.  In
> the case of a failover (active MGC fails) the standby becomes active
> and sends ASPACT(OVERRIDE).
> 
> The M3UA draft does not allow changing between override and standby
> traffic modes, since it requires an error message when a mode
> different from the currently configured one is received:
> 
>    from 4.3.4.4 ...
>    If the traffic handling mode of the Application Server is not
>    already known via configuration data, then the traffic handling
>    mode indicated in the first ASP Active message causing the
>    transition of the Application Server state to AS-ACTIVE MAY be used
>    to set the mode.
> 
> One of our concerns is when there is too much traffic for a single ASP
> to handle, but we want to use an active/standby configuration.  I.e.,
> need override mode, but need to switch between sets of ASPs rather
> than single ASPs. Suggestions?

TMT is optional everywhere.  SG and ASP can always be statically
configured for whatever other traffic distribution patterns their
implementors care to imagine.  I know that doesn't speak much to
interoperability, but where close coupling is required...

Your problem is illustrative of the fact that one might need to
group ASPs.  I have the beginnings of an extension draft which
provides for a load-selector which would describe an ASPs placement
in a load-group.  TMT would be applicable between load groups and
load-selection within a load-group.  This would allow you to pool
ASPs into a load-group yet distribute traffic between groups.
Load-selection within a load-group could be on the basis of fixed
load-selection within the group, loadsharing within the group, or
broadcast within the group.  This would allow for the equivalent
of striping *and* mirroring.  (Now we have only striping *or*
mirroring.)

It is a fairly easy thing to do in extension draft.  All that it
adds is an optional load-selector parameter to RKMM/ASPTM messages
for the ASP to indicate its position within the group (and possibly
the SGP to indicate its position back).

Interested?

--brian

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

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From: Verwimp Gery <[email-masked]>
Date: Fri, 16 Nov 2001 09:44:27 +0100

Hi,

What we need instead of dynamic changes in the TMT, is some congestion/flow
control in the ASPTM messages. ASPs could e.g. refuse to receive new calls
etc.

Also, the TMT itself could be more refined, because sending notifications
and awaiting active/active_ack doesn't cut it if one wants an immediately
available backup that however doesn't get any traffic for the RC under
normal circumstances.

Loadshare mode could be defined as n+k (n ASPs actively loadsharing in
normal conditions, k backups ready to get traffic without further notice),
override mode reduces to 1+k loadshare mode.

Within a loadsharing group, broadcast groups could be defined. All these
groups are defined at configuration/registration time; an ASP cannot alter
this dynamically via ASPTM ... we actually would change the RC then.

Comments ?

____________________________

Gery Verwimp
> SIEMENS ATEA
> ICN D CS D5
> Tel. : +32 14 25 3424
Fax : +32 14 25 3212
mailto:[email-masked]
____________________________________

-----Original Message-----
From: Mark Davidson [mailto:[email-masked]]
Sent: donderdag 15 november 2001 22:22
To: sigtran
Subject: Re: Can Traffic Mode be Dynamic?

My understanding of override mode is that it is used for handling
connections to
active/standby
equipment (e.g. MGC) and allows the active portion of the equipment to
direct
traffic towards itself.
In the case of a failover (active MGC fails) the standby becomes active and
sends ASPACT(OVERRIDE).

   from 4.3.4.4 ...

   If the traffic handling mode of the Application Server is not already
known
   via
   configuration data, then the traffic handling mode indicated in the
   first ASP Active message causing the transition of the Application
   Server state to AS-ACTIVE MAY be used to set the mode.

One of our concerns is when there is too much traffic for a single ASP to
handle, but
we want to use an active/standby configuration.  I.e., need override mode,
but
need to switch
between sets of ASPs rather than single ASPs. Suggestions?

-Mark Davidson
[email-masked]

Thanks,

Jacques Rajchgod
MCI Worldcom

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