[cisco-voip] CAC Recommendation for a VoIP Network

[Ted Nugent]

Honestly no offense intended however, I'm afraid that
you might need to take another look at the SRND and/or
understand how Locations based CAC actually works.
Location based CAC uses the CallAgent (CM) as the
point of reference for all calculations and
adds/subtracts bandwidth in reference to the CM
Cluster Location (aka hub spoke). If you are using a
partial or fully meshed topology your calls will
nullify these calculations. Let take for example the
stick figure topology below.

      Site1
HQ <    |
      Site2

Links from HQ to Site1 and Site2 and another link
between Site1 and Site2 directly. If a g729 call is
made from Site1 to Site2 and your not "forcing" the
voice path to hub spoke, the call is traversing the
direct link between Site1 and Site 2 however CM
assumes the call goes from Site1 to HQ and then to
Site2 and ticks off 24kps from each location (link),
when in actuality the call is not touching these
links. This is a very simply scenario but I think you
can under the basis. 
If you don't believe me or the SRND then feel free to
take a look at your locations in perfmon. GK CAC is a
bit more forgiving in its zone configuration however
it suffers from the same probably that it is not aware
of the topology. 

If you feel I'm missing something then please
elaborate. I'm all ears.

SRND
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a00806e8c1e.html#wp1073144






--- Craig M Staffin <cmstaffin at ra.rockwell.com> wrote:

> Ted,
> 
> This really is not true.  We have a full mesh
> network through VPN and we 
> use CCM CAC and it works great.  We have calls from
> and to many sites at 
> one point in time.  How locations work in CCM is
> that you add all things 
> physically at the site into one location and so on. 
> There for even if you 
> have 20 sites all connected any call out of that
> site will count against 
> the total.  I also do not know why GK wouldn't be
> able to do the same 
> thing as it works the same way.
> 
> Craig
> 
> 
> 
> 
> Ted Nugent <tednugent69 at yahoo.com> 
> Sent by: cisco-voip-bounces at puck.nether.net
> 02/01/2007 07:31 PM
> 
> To
> embeleco <embeleco at gmail.com>,
> cisco-voip at puck.nether.net
> cc
> 
> Subject
> Re: [cisco-voip] CAC Recommendation for a VoIP
> Network
> 
> 
> 
> 
> 
> 
> Unless you "force" the voice path to hub-spoke which
> could break your CAC if a link goes down your stuck
> using RSVP. Neither GK CAC nor Locations based CAC
> are
> Topology aware and require a hub spoke topology of
> some sort.
> 
> 
> --- embeleco <embeleco at gmail.com> wrote:
> 
> > Hi.
> > 
> > I would like CAC recommendations for a VoIP
> network
> > that consist of 6-10
> > (backbone sites) sites connected in a fully mesh
> > topology (not
> > hub-and-spoke). Currently is a toll-by-pass
> solution
> > consisting of Legacy
> > PBX connected to Cisco VoIP Gateways using
> > ISDN-PRI/Q.SIG signaling. Also
> > customer has Gatekeepers in order to centralized
> > dialplan. We are defining
> > which CAC (Call Admission Control) to use with the
> > fully mesh topology.
> > 
> > We were thinking to use CAC at the gatekeeper but
> > that will work best for
> > hub and spoke scenarios. It meas that gatekeepers
> > will not know where the
> > call is going within the network... the other CAC
> > solution that we are
> > considering is RSVP.
> > 
> > 
> > Any suggestions? Recommendations? Which CAC
> solution
> > to consider?
> > 
> > Thanks in advanced.
> > > _______________________________________________
> > cisco-voip mailing list
> > cisco-voip at puck.nether.net
> >
> https://puck.nether.net/mailman/listinfo/cisco-voip
> > 
> 
> 
> 
> 
>  
>
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