[cisco-voip] H.323 MTP Usage

[Nick Matthews]

For what it's worth - you can use CPU cycles on your router instead of
PVDM hardware for MTPs.  This works great when you have a few one-off
cases you need some MTPs for and say a 3845 that's not using all of
it's CPU.  It will do both G729 and G711 in software on the router.

-nick

On Tue, Apr 27, 2010 at 8:50 PM, Tom Mc <tomdmc at gmail.com> wrote:
> Thanks Jason,
>
> The purpose of the MTP is purely from a perspective of controlling the
> path that the rtp stream takes through the network.
> I'm getting push backs from the guys managing the core routing, but
> I'm managed to convince them to import the /32 h323 source loopback
> addresses for the international gateways into the domestic vrf which
> is the best solution.
> I'm now waiting to find out if they are in a contiguous block
> (something that I'm hoping is the case)
>
> Cheers,
> Tom
>
> On Wed, Apr 28, 2010 at 6:42 AM, Jason Aarons (US)
> <jason.aarons at us.didata.com> wrote:
>> From a design standpoint it's always best to avoid using MTPs.  Is the reason you need a MTP because the PBX doesn't support H.323v2 and Empty Capabilities Set?
>>
>> My past experience is that MTPs are undesireable due to scalability (unless you got money to burn on PVDMs), and that checking MTP is usually a workaround for a bug, etc.
>>
>> ________________________________________
>> From: cisco-voip-bounces at puck.nether.net [cisco-voip-bounces at puck.nether.net] On Behalf Of Tom Mc [tomdmc at gmail.com]
>> Sent: Tuesday, April 27, 2010 4:19 PM
>> To: Ryan Ratliff
>> Cc: cisco-voip at puck.nether.net
>> Subject: Re: [cisco-voip] H.323 MTP Usage
>>
>> Thanks guys,
>>
>> I'm using g.729. 'Software MTP only supports g.711', that would
>> explain it. I'm using dynamips in my test lab so I cannot test with a
>> xcode resource but it might be a possible solution.
>> The other option being using an IP-to-IP GW to terminate the call at
>> the cluster site, I was leaning this way myself but I adds a layer of
>> complexity that I may not get though by the weekend (wheels turn
>> slowly in this project).
>>
>> Cheers,
>> Tom
>>
>>
>>
>> On Tue, Apr 27, 2010 at 11:42 PM, Ryan Ratliff <rratliff at cisco.com> wrote:
>>> What codec is getting used for the calls through the MTP?  The software MTP only supports g.711 and if you are using any other codec CUCM will try to allocate a transcoder and this part sounds like it is failing based on your description.
>>>
>>> -Ryan
>>>
>>> On Apr 27, 2010, at 7:58 AM, Tom Mc wrote:
>>>
>>>> Hi guys,
>>>>
>>>> I have a query about how mtp can be implemented with h.323 gateways.
>>>>
>>>> We are going through a migration for a customer replacing a LCR solution.
>>>> Topology looks something like this:
>>>> PBX --> QSig --> 3845 --> H.323 --> CUCM 7.1 --> H.323 --> 3845 --> QSig --> PBX
>>>> CUCM has been configured for call routing using route patterns with
>>>> h.323 gateway destinations
>>>>
>>>> This solution has been implemented internationally for about 40 sites
>>>> all with 'any to any' connectivity which has not been a problem.
>>>> We now need to cutover Australia, and I have just been told that
>>>> routing to the other 40 sites at this point in time is not possible
>>>> and that media traffic will need to be routed via the CUCM cluster.
>>>>
>>>> I've tried to lab up this solution (replacing the pbx with ip phones)
>>>> trying to get the gateways to use an MTP (which is registered) and
>>>> thus forcing the media stream out to the internationally hosted CUCM
>>>> cluster.
>>>>
>>>> Ticking the box "Media Termination Point Required" in the gateway
>>>> config and assigning a MRGL with the CUCM software MTP's does not seem
>>>> to work.
>>>> Wireshark shows the media stream from GW to GW not GW to CUCM to GW as expected.
>>>> Setting the service parameter  "Fail Call If MTP Allocation Fails" to
>>>> true, predictably ends the call on answer attempt.
>>>>
>>>> Is what I am attempting to do possible with the CUCM software MTP's?
>>>> Do I need hardware resources to do this?
>>>>
>>>> The "Help, this page" on the gateway config page tells me the
>>>> following (which sort of tells me that this is not the purpose of the
>>>> MTP):
>>>>
>>>> "If you want a Media Termination Point to implement features that
>>>> H.323 does not support (such as hold and transfer), check the check
>>>> box.
>>>>
>>>> Use this check box only for H.323 clients and H.323 devices that do
>>>> not support the H.245 Empty Capabilities Set message.
>>>>
>>>> If you check this check box to require an MTP and this device becomes
>>>> the endpoint of a video call, the call will be audio only."
>>>>
>>>>
>>>> Cheers,
>>>> Tom
>>>> _______________________________________________
>>>> cisco-voip mailing list
>>>> cisco-voip at puck.nether.net
>>>> https://puck.nether.net/mailman/listinfo/cisco-voip
>>>
>>>
>>
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