Mitel IP Trunking on the 3300

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I have a question about IP trunking and call admission control on the
3300, and I'm hoping someone here might be able to answer it.

I'll try to do a diagram to explain my question a little better.
Imagine the following network:

    A
   / \\
  /   \\
B ----- C

The lines represent the IP trunks on the 3300, not physical circuits;
however, we'll assume that these sites are fully meshed from a network
perspective, as well.

Now, let's say we have a maximum of three calls configured per trunk.
If there are already three calls in place between A and B, what happens
when one more person at A tries to call B? Will the call be blocked
because the IP trunk between A and B is full, or will the 3300 at A
realize that there is another path to B through C?

Thanks,
John



Re: Mitel IP Trunking on the 3300



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Ip trunking uses the same rules as normal trunking. So as long as you have a
route list setup to that then yes it will.

Ian




Re: Mitel IP Trunking on the 3300


What if this is for internal IP calls only? I was told that with the
3300 we would not have to do any configuration regarding a dial plan
for internal calls and that all PBXs would automatically learn where
all internal extensions resided. Based on your response, it almost
sounds like we'd have to construct a dialing plan for internal calling
as well as for external calling.

Is that true?



Re: Mitel IP Trunking on the 3300



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No

A call to an extension on switch B from switch A is an external call.
Even if  your system clustered or resilaint.  a user it looks like one
system but routes are still setup between systems s users can call between
systems.

How much do you know about sysadmin on the 3300 ? Do you understand ARS and
route lists ? If you do I will be happy to explain in more detail.

Ian




Re: Mitel IP Trunking on the 3300


I'm only slightly familiar with ARS. My company is evaluating a couple
of different VoIP solutions and Mitel is one of them. I'm trying to
make sure I understand this subject because it has some pretty serious
design implications for us.

So, let's say we started out with the three-node site I mentioned
earlier. Later, we a fourth site, then a fifth site, and so on. Will I
need to go back to the previously-installed PBXs and configure ARS so
that they know how to reach the internal extensions at the new sites?



Re: Mitel IP Trunking on the 3300



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Ok

I will assume that you will be managing the systems with Ops/Ent manager. If
not you will need to go back to the dealer and ask why they havent designed
your solution correctly.

So very briefly here is how it works..

All your systems will be given a node ID. for example 201 for site A 202 for
site B and 203 for site C, As sites are added they are given the next ID
The Node is referenced by the ceid so ceid 1 is node 201 etc.

you then create routes on your systems A-B A-C B-C etc

we then have ex2001 on system A ex2002 on system B and ex2003 on system C.
these when set up in Ops are defined as to which system they are on so 2001
is routed by the system as 2012001 if called from system B but as a user you
dial 2001 . The remote directory takes care of the lookup as to how to route
the call. then the ARS for 201 with  4 following digits takes care of how it
is physicly routed

I hope thats not too confusing, When training engineers I usually take over
a day to go over this bit of clustering.

So in conclusion yes you will have to add routes as you add systems but if
the cluster is planned well its very very simple and very resiliant.

Ian Plain

www.cyber-cottage.co.uk

Free world Dial 43143




Re: Mitel IP Trunking on the 3300


There is some programming required, but its not complicated. You tell each
system the IP addresses of the other and create the ARS needed to reach each
3300. Because the PBX's can have the same extension numbers ( conflict
dialing ), I think "learning" what extensions are where, could create
problems.


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Re: Mitel IP Trunking on the 3300



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Re: Mitel IP Trunking on the 3300


Who ever told you that is incorrect. The 3300's don't learn routes like a
router. They must be programmed. You don't say if your A, B and C are
clustered or not.


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Re: Mitel IP Trunking on the 3300


They would be clustered. Does this type of arrangement scale well if
you have a fully-meshed data network? We have over 110 locations, over
80 of which would need a 3300. This type of design seems like it would
work okay in a smaller network or in a partially-meshed environment,
but perhaps it isn't the best choice for a network this size.

What are your thoughts on this?

Many thanks,
John



Re: Mitel IP Trunking on the 3300



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Well I have one customer with over 50 SX2000 and by the end of the migration
ovr 250 3300's
Clustering is a very robust tecnology. And when done with IP trunking as
long as a there is a link between sites they can be trunked, remeber
clustering is also supported over MSDN trunks as well so even if you dot
have a data link they can be clustered.
Basicly it will be down to design as to how well it works.

The only other solution that will scale in the sameway is a Cisco one.

Ian





Re: Mitel IP Trunking on the 3300


One problem I have with this approach is that we'll have 110+ sites
that are fully-meshed on the data network (MPLS-based VPN). We want to
have any-to-any connectivity for data and voice. With Mitel, the voice
data traffic is any-to-any but the signaling traffic has to follow
these IP trunks. That means that call admission control (maximum calls
per trunk) is based on a path entirely different from the actual voice
path, and that's going to cause problems for us.



Re: Mitel IP Trunking on the 3300



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Hi
Ok. I think you may be missunderstanding on how Ip tunking works.
Its all IP, And on most IP systems the voice and control are seperate.
control has to go via a contoller. but the rtp traffic is Set to set or set
to contoller if its to a TDM device.
IP trunking is a way of limiting call traffic on a link So for example
between site a and b you have a 2 meg link but always want 1 meg avalible
for data you would define 10 ip trunks (assuming G711).

Why do you assume you will have problems? All calls are in the IP cloud and
as is the way of IP clouds they find their way by the lowest cost route.

Ian




Re: Mitel IP Trunking on the 3300


You described the precise problem: the voice RTP traffic is set-to-set
while the signaling follows the IP trunks. However, the call admission
control is based on the signaling path, NOT the voice path! This is
really annoying because we have a fully meshed data network. If we
don't design it correctly we could end up blocking calls to sites that
have plenty of bandwidth or allowing calls to sites that don't have
enough bandwidth.

Take my initial diagram as an example, assuming 5 calls allowed per
trunk. If all three sites are available than A could potentially make
10 calls to B. However, if C falls off the network, A can only make 5
calls to B despite the fact that the bandwidth available hasn't changed.



Re: Mitel IP Trunking on the 3300



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As you say, It down to good design.

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The chance of a system falling off the network is remote. and yes 3 sites
are not that resiliant.
Up the sites to 4 and then look at the routing, but in reality if you have
bandwidth avalible for 10 calls then you should have 10 channels between
sites.

You cant base a decision on resiliancy by how  3 systems route, when you say
you are looking a 100+ systems. You need to to look at what happens with 100
systems and one drops off.

But in the end it works and is proven.

Ian









Re: Mitel IP Trunking on the 3300


The 3300s are pretty robust John. Even in as complex of a network design
as you propose I honestly doubt you're going to be seeing controllers
dropping out, certainly no moreso than the circuit path to them. Keep them
running in clean, temp-stable environments on clean UPS-backed power as
you would any other mission-critical piece of gear and I think you'll find
them at least as reliable as the rest of your network hardware. These also
run the same proven call control that's been in the SX-2000 product for a
couple of decades. In a temp-stable 68~72-degree room they'll run just
fine even with the fans disabled. The price you pay is for first line,
carrier-class gear. There are no Radio Shack parts inside.


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Re: Mitel IP Trunking on the 3300


I'm not thinking in terms of controllers failing. I'm more concerned
with a circuit failure at a site, which is far more common. And I
realize that three sites doesn't translate to 100, I was just wanting
to make sure I understood how it worked. My manager and I have
brainstormed for quite a while, trying at least eight different IP
trunk network designs and we haven't found one that fully meets our
requirements. We either lose on resiliency or we lose by not being able
to *tightly* control the amount of bandwidth in use for voice at a
specific site (not on a trunk.)

The number of calls on a virtual IP trunk is irrelevant! I want to be
able to control how much bandwidth is in use on a circuit regardless of
the number of calls and mixture of codecs. Their implementation makes
sense if you have a partially-meshed data network because your data has
to follow your trunk paths (well, sort of.) We have a fully-meshed data
network so it makes no sense for call admission control to be based on
these virtual trunks when the voice calls don't follow the same path.

I have a meeting with Mitel on Monday that will allow them to clear
this up for me. The entire purpose of the meeting is to discuss this
design issue. I'll be sure to let everyone know how it turns out.

Thanks!
John



Re: Mitel IP Trunking on the 3300


You need to spend more time studying this as you appear not to understand
how IP trunks work on a 3300.


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