[cisco-voip] T1 Clock source question

[Dave Goodwin]

Disclaimer: I haven't deployed ISR4ks yet, not even in a lab environment to
try this out. However, the "Clocking" section on the following page seems
to disagree with something you've said. This page indicates there is a
"backplane clock" which certainly reads like a TDM bus. It's not clear what
it buys us, except more potential for clock collisions from different
providers!
http://www.cisco.com/c/en/us/support/docs/routers/4000-series-integrated-services-routers/118792-config-isr-00.html#anc7

That said, the page definitely states that TDM cards ports cannot utilize
the motherboard PVDM, and suggests to use the motherboard PVDM for DSP
services like conf/xcode. Oddly, it does not say whether unused PVDM
channels on the NIM PVDM could be used for DSP services as well. It also
does not say whether PVDM channels can be shared from one NIM to another.
Without further guidance or testing, I guess we should assume neither is
possible, and that all TDM circuit terminating PVDMs must be in that exact
NIM, and all DSP services like conf/xcode must be from the motherboard.

-Dave

On Wed, Apr 22, 2015 at 6:32 PM, Jeremy Bresley <brez at brezworks.com> wrote:

> On 4/22/2015 3:23 PM, Andrew Dorsett wrote:
>
>> Rob is correct in that you can use NMs that support DSPs on the NM to
>> have separate clocking domains.  On the new ISR4k line, we have the option
>> of placing DSPs on the T1 module (NIM) which will allow us to support
>> multiple clocking domains.  Some people are placing DSPs on the NIM for the
>> T1 interface and then DSPs on the on-board slots for DSP farm applications.
>>
>>
>>  One slight correction there from recent discussions with a TME on the
> ISR line.  You don't have the option of doing that on the ISR4Ks, you HAVE
> to do that.  There is no TDM bus in the ISR4Ks, so you can't share DSPs
> between a NIM and the motherboard.  So DSPFarm use requires a separate
> PVDM4 from the one being used for the NIM. Which may make a significant
> difference in what you need to order if you've been in the habit of
> ordering larger capacity PVDMs and sharing them between VWICs and DSPFarm
> in the past on ISR/ISR G2s. What we will probably do when we start
> installing ISR4Ks at our remote sites in the near future is to order a
> PVDM4-32 with the NIM to support using it for a single PRI, and continue
> getting a 32 or 64 for DSPFarm usage.
>
> Jeremy "TheBrez" Bresley
> brez at brezworks.com
>
> _______________________________________________
> cisco-voip mailing list
> cisco-voip at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-voip
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://puck.nether.net/pipermail/cisco-voip/attachments/20150422/c9537352/attachment.html>