Subject: Call agent issue

From: Hiren Shah <[email-masked]>
Date: Wed, 26 Apr 2000 13:27:44 +0530

Hi all
I have a small doubt in concept.
Is there a one to one relationship between a call agent and a media gateway.
If not, then what are the considerations involved for having more than one call agent.
One of the consideration is that the media gateways may be of different vendors and therefore there the call agents also will be different .
Lets assume that the media gateways are from the same vendor and provide a standard and identical interface.
Now if this is the case ,will the geographical locations of the media gateways  have an impact on the decision whether there has to be a call agent per gateway.
Please clarify my doubt and please give me the attributes that matter in making a desicion to deploy more than one call agents.

regards
Hiren

A Candle never  loses any of its light by lighting other Candles

---

From: "Rosen, Brian" <[email-masked]>
Date: Wed, 26 Apr 2000 08:05:41 -0400

Hi all
I have a small doubt in concept.
Only one?  Keep thinking, you are sure to find more!!!

Could be, but usually thought of as one to many in the current version, with
the possibility
of many to many.

If not, then what are the considerations involved for having more than one
call agent.
Lots, I'll go through yours and then add some more

One of the consideration is that the media gateways may be of different
vendors and therefore there the call agents also will be different .
Sure, we would say that Media Gateways implement packages on terminations.
In order
to assure that a Call Agent (we call them Media Gateway Controllers) can
properly control
a Media Gateway, the MGC has to support the packages of the MG.  So if you
had more than
one MGC that was different, one way to decide which MGC controlled which MGs
would
be which MGC implemented support for the packages implemented on the MGs.
For simplicity
we also have the "profile" concept, where if the MG and MGC implement the
same profile,
then they are compatible.

Lets assume that the media gateways are from the same vendor and provide a
standard and identical interface.
Or all the MGs implement the same profiles, or the MGCs all implement the
union of the profiles
implemented on the MGs to be controlled

Now if this is the case ,will the geographical locations of the media
gateways  have an impact on the decision whether there has to be a call
agent per gateway.
While it's possible that geography determines this, it would be a side
effect of network connectivity.   You need addressibility and some amount of
bandwidth between the MG and
MGC, and latency is also an issue.  Sometimes, network elements physically
nearer to one another have better connectivity.  This is not the case in
many networks however.

Please clarify my doubt and please give me the attributes that matter in
making a desicion to deploy more than one call agents.
Here is my list, others may have more:
    1. Administrative domain - a network may have more than one
administrative domain.
            Assignment of MGs to MGCs may be made on administrative domain
boundaries
    2. Bandwidth/latency as discussed above
    3. Call capacity.  A set of MGs may be able to generate a very large
number of calls.
            A MGC  has some limit to the number of calls it can handle.  You
add MGCs to
            your net to allow more calls
    4. Services.  Different MGCs may offer different services.  An MG may be
attached to
            a specific MGC based on what services it requires
    5. Reliability, there are mechanisms to support handoff of an MG from
one MGC to
            another.

Please also note that an MG may be controlled by more than one MGC.  See the
discussion
of "Virtual MGs" in the text.  This is how you get many to many connections.

regards
Hiren

---

From: Tom-PT Taylor <[email-masked]>
Date: Wed, 26 Apr 2000 08:09:15 -0500

I assume that by "Call Agent" you mean what in Megaco we call the MGC (Media
Gateway Controller).  This isn't an automatic assumption -- the architecture
above the MG could be more complicated -- but it's reasonable.

First point: the whole reason to define a standard is so different vendors'
products can interwork.  Just because you have media gateways from multiple
vendors doesn't mean they can't be controlled by the same call agent.

Second point: in my engineering judgement, it is hard to see that having a
call agent per media gateway would be economic.  You might as well combine
the two units, eliminating the cost of supporting the Megaco/H.248
interface.  The whole point of the decomposition into call agent/MGC and
media gateway components is to achieve economies through geographic
dispersion of the complete gateway function.

> -----Original Message-----
> From: [email-masked] [SMTP:[email-masked]]
> Sent: Wednesday, April 26, 2000 3:58 AM
> To:   [email-masked]
> Subject:      Call agent issue
>
> Hi all