[cisco-voip] Transcoding/Conferencing on the same ISDN Gateway

Fri Feb 12 01:28:29 EST 2010

These are from general numbers I've looked at in terms of CUBE
scalability.  It's not as drastic as 50%, and by that I mean more like
35-40%.  What really kills the CPU is the PPS that go directly to the
CPU because the RTP packets are targeted to a directly connected IP
address. It's the exact same reason why you get 10-15% more usage out
of vad on, because there is a linearly scaled number fewer packets
with that feature on.

-nick

On Thu, Feb 11, 2010 at 11:13 PM, Rhodium <rhodium_uk at yahoo.co.uk> wrote:
> Hi Nick,
>
> Thanks for the info. It re-iterates what is stated in the SRND and what I know of CPS.
>
> Quite an interesting fact about how MTP, etc approximately halve the number of calls, I assume simultaneous calls? Didn't think it was that drastic. Any documentation on that or just "experience"?
>
> Regards,
>
> J
>
> --- On Fri, 2/12/10, Nick Matthews <matthnick at gmail.com> wrote:
>
>> From: Nick Matthews <matthnick at gmail.com>
>> Subject: Re: [cisco-voip] Transcoding/Conferencing on the same ISDN Gateway
>> To: "Rhodium" <rhodium_uk at yahoo.co.uk>
>> Cc: "Matthew Saskin" <msaskin at gmail.com>, cisco-voip at puck.nether.net
>> Date: Friday, February 12, 2010, 1:42 AM
>> FWIW, if you're looking at 5+ CPS
>> you're probably looking at an
>> AS5X000 box.  Many of the concurrent call numbers that
>> are calculated
>> for gateways are not done at that high of a call rate
>> (implying short
>> duration calls).
>>
>> Regardless, you can run everything you want on the router
>> (VPN, MTP,
>> Xcoding, full BGP table) as long as the parameters of the
>> equation are
>> right.  If you scale your gateway the only problem is
>> CPU usage, not
>> feature overload.  The only addendum to that is that
>> most of these
>> numbers are calculated individually, so when you mix and
>> match the
>> calculations aren't quite as accurate.  Which doesn't
>> say much,
>> because depending on your call patterns you may get
>> different results
>> from the posted numbers anyways.  Long calls = better
>> for CPU, vad on
>> = better for CPU, codec selection = doesn't matter.
>> Most of the
>> problem you run into is the pure PPS of these streams
>> rather than the
>> overhead, which is why MTPs and such can get you higher CPU
>> pretty
>> quickly.  Xcoding and MTP roughly halve the amount of
>> calls you can
>> make through the box.
>>
>> hth,
>> nick
>>
>> On Wed, Feb 10, 2010 at 5:21 PM, Rhodium <rhodium_uk at yahoo.co.uk>
>> wrote:
>> > http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/gateways.html#wp1043594
>> >
>> > I am referring to CPS and not simultaneous call
>> volumes. We have multiple gateways decked with 210 channels
>> each (7 x E1) for redundancy and have higher call volumes
>> but we are focused on CPS as that brings down the number of
>> simultaneous calls on the gateways.
>> >
>> > Also our BHCA is in the region of 8000 so there is a
>> slight difference in type of traffic flow we are seeing.
>> >
>> > Regards,
>> >
>> > J
>> >
>> > --- On Wed, 2/10/10, Matthew Saskin <msaskin at gmail.com>
>> wrote:
>> >
>> >> From: Matthew Saskin <msaskin at gmail.com>
>> >> Subject: Re: [cisco-voip] Transcoding/Conferencing
>> on the same ISDN Gateway
>> >> To: "Rhodium" <rhodium_uk at yahoo.co.uk>
>> >> Cc: "Peter Slow" <peter.slow at gmail.com>,
>> cisco-voip at puck.nether.net
>> >> Date: Wednesday, February 10, 2010, 10:01 PM
>> >> Where in the SRND is the call limit
>> >> for various gateways listed?  I'd like to take a
>> >> look.
>> >>
>> >> The environment I was referring to was a UCCE
>> build
>> >> performed by Cisco AS.  4 gateways w/ 10-12 PRI's
>> each
>> >> handling upwards of 50K calls/day inbound and
>> outbound - all
>> >> calls were transcoded on these gateways after the
>> IVR and
>> >> before heading to agents.  During busy hour call
>> volumes
>> >> weren't above 250 calls/gateway but I'd like to
>> see
>> >> the reference.
>> >>
>> >>
>> >> Matthew Saskin
>> >> msaskin at gmail.com
>> >> 203-253-9571
>> >>
>> >> July 18, 2010 - 1500m swim (in the hudson), 40k
>> bike, 10k
>> >> run
>> >> Please support the Leukemia & Lyphoma Society
>> >>
>> >> http://pages.teamintraining.org/nyc/nyctri10/msaskin
>> >>
>> >>
>> >>
>> >> On Wed, Feb 10, 2010 at 4:53 PM,
>> >> Rhodium <rhodium_uk at yahoo.co.uk>
>> >> wrote:
>> >>
>> >> Hi Matthew,
>> >>
>> >> Appreciate the feedback. I am just concerned that
>> as this
>> >> is for a call centre, when the number of calls per
>> second
>> >> (CPS) increases, the number of simultaneous calls
>> >> decreases... so I can see a deployment with 1 to 3
>> CPS
>> >> working with the setup you have described but with
>> something
>> >> close to around 15 CPS, then according to the
>> SRND, that is
>> >> a maximum of 255 calls (for a 3845). As we are
>> decking out
>> >> the ISDN router with 210 channels, then that only
>> leaves
>> >> headroom for 45 calls not including CPU overhead
>> of SCCP,
>> >> which led to my mistaken recollection of
>> transcoders and
>> >> ISDN GWs when it was transcoders and CUBEs.
>> >>
>> >>
>> >> I guess based on the setup I described, the more I
>> think
>> >> about it, the more I am inclined to make it "off
>> >> box". Am I over riding financial judgement with
>> caution
>> >> too much?
>> >>
>> >> Regards,
>> >>
>> >> J
>> >>
>> >>
>> >>
>> >> --- On Wed, 2/10/10, Matthew Saskin <msaskin at gmail.com>
>> >> wrote:
>> >>
>> >> > From: Matthew Saskin <msaskin at gmail.com>
>> >>
>> >> > Subject: Re: [cisco-voip]
>> >> Transcoding/Conferencing on the same ISDN Gateway
>> >> > To: "Rhodium" <rhodium_uk at yahoo.co.uk>
>> >> > Cc: "Peter Slow" <peter.slow at gmail.com>,
>> >> cisco-voip at puck.nether.net
>> >>
>> >> > Date: Wednesday, February 10, 2010, 9:37 PM
>> >>
>> >>
>> >>
>> >> > I regularly see single gateways
>> >> handle
>> >> > all functions (PSTN termination,
>> conferencing,
>> >> transcoding)
>> >> > for sites of all sizes.  I know of nothing
>> >> [design-wise]
>> >> > preventing you from doing this.  In fact, I
>> can think
>> >> of
>> >>
>> >> > some very large installations I've seen that
>> were
>> >> done
>> >> > by advanced services where 3845's were being
>> used
>> >> to
>> >> > terminate 10-12 PRI's plus handle a few
>> hundred
>> >> > transcoding sessions.
>> >>
>> >> >
>> >> >
>> >> > Matthew Saskin
>> >> > msaskin at gmail.com
>> >> > 203-253-9571
>> >> >
>> >> > July 18, 2010 - 1500m swim (in the hudson),
>> 40k bike,
>> >> 10k
>> >> > run
>> >> > Please support the Leukemia & Lyphoma
>> Society
>> >>
>> >> >
>> >> > http://pages.teamintraining.org/nyc/nyctri10/msaskin
>> >> >
>> >> >
>> >> >
>> >> > On Wed, Feb 10, 2010 at 4:24 PM,
>> >> > Rhodium <rhodium_uk at yahoo.co.uk>
>> >>
>> >> > wrote:
>> >> >
>> >> > Hi Peter,
>> >> >
>> >> > Thank you for your reply.
>> >> >
>> >> > I dug out a report from Cisco Advanced
>> Services that
>> >> stated
>> >> > that CUBEs should only be used for SIP trunks
>> and not
>> >> for
>> >>
>> >> > transcoding/mtp. Knew I read something
>> somewhere. Just
>> >> not
>> >> > the details... :)
>> >> >
>> >> >
>> >> > So we are all definite that for an ISDN GW,
>> we can
>> >> use
>> >> > re-use the DSPs for transcoding in line with
>> >> Cisco's
>> >>
>> >> > recommendations? I want to recommend getting
>> a
>> >> dedicated
>> >> > router for these functions but need to
>> justify the
>> >> cost so
>> >> > if there are no design recommendations, then
>> I guess I
>> >> can
>> >> > just put it all on one box.
>> >>
>> >> >
>> >> >
>> >> > Regards,
>> >> >
>> >> > J
>> >> >
>> >> >
>> >> > --- On Wed, 2/10/10, Peter Slow <peter.slow at gmail.com>
>> >> > wrote:
>> >> >
>> >> > > From: Peter Slow <peter.slow at gmail.com>
>> >>
>> >> >
>> >> > > Subject: Re: [cisco-voip]
>> >> Transcoding/Conferencing on
>> >> > the same ISDN Gateway
>> >> > > To: "Rhodium" <rhodium_uk at yahoo.co.uk>
>> >> > > Cc: cisco-voip at puck.nether.net
>> >>
>> >> >
>> >> > > Date: Wednesday, February 10, 2010, 5:02
>> PM
>> >> >
>> >> >
>> >> >
>> >> > > That is not necessarily correct. It
>> >> > > depends heavily on the type of
>> >> > > gateway you're talking about, and the
>> number
>> >> of
>> >>
>> >> > transcoding
>> >> > > or
>> >> > > conferencing sessions you might be
>> needing.
>> >> >
>> >> > >
>> >> > > -peter
>> >> > >
>> >> > > On Wed, Feb 10, 2010 at 7:24 AM, Rhodium
>> <rhodium_uk at yahoo.co.uk>
>> >>
>> >> > > wrote:
>> >> > > > Hi Experts, :)
>> >> > > >
>> >> > > > I am sure I read somewhere in a
>> design doc
>> >> or the
>> >> > SRND
>> >> >
>> >> > > that it is not advocated to put
>> transcoding or
>> >> > conferencing
>> >>
>> >> > > resources on a voice gateway handling
>> about 150
>> >> > calls.
>> >> > > >
>> >> > > > Am I recalling right or are the old
>> brain
>> >> cells
>> >> > > getting weaker with age.
>> >> >
>> >> > > >
>> >>
>> >> > > > If that is correct, a link would
>> be
>> >> appreciated
>> >> > as I
>> >> > > can't find it.
>> >> > > >
>> >> > > > Regards,
>> >> > > >
>> >> > > > Jason
>> >> > > >
>> >> > > >
>> >>
>> >> > > >
>> >> > > >
>> >> >
>> >> > > >
>> >> _______________________________________________
>> >> > > > cisco-voip mailing list
>> >> > > > cisco-voip at puck.nether.net
>> >>
>> >> > > > https://puck.nether.net/mailman/listinfo/cisco-voip
>> >> >
>> >> > > >
>> >> > >
>> >> >
>> >> >
>> >> >
>> >> >
>> >>
>> >> >
>> _______________________________________________
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>> >> > cisco-voip at puck.nether.net
>> >> > https://puck.nether..net/mailman/listinfo/cisco-voip
>> >>
>> >> >
>> >> >
>> >> >
>> >> >
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >
>> >
>> >
>> >
>> > _______________________________________________
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>> >
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