[cisco-voip] Clocking/slips issue with Nortel

[Nick Matthews]

Hi Andrius,

In this scenario it would be more practical for Nortel to provide the
clock since they are receiving it on the PSTN.  For Cisco routers at
least, each set of DSPs can only keep track of 1 clock.  Unless you
have an HDV plus DSPs on the motherboard, you have one set of DSPs,
and Nortel is likely in the same scenario.  The way you've described
it they need to keep up with your internal clock plus the PSTN clock.

Have them set themselves as network, and set clock source line.  I
don't believe the network clock select commands will be properly
applied when you're doing internal clock anyway, but you will need it
when you are in clock source line.

Other than that, try different cables/hardware, or use nortel commands
to reduce the dB if they exist.

-nick

On Tue, Dec 15, 2009 at 9:01 PM, Andrius Kislas <andrius-conf at kislas.lt> wrote:
> Hi,
>
> I have a clocking / slips problem connecting Cisco 3845 to Nortel
> CS1000M r4.5. The scenario is following:
>
> Nortel is already connected to PSTN and is getting clock from network
> (PSTN). Now I connect C3845 to Nortel using QSIG protocol and NM modules
> NM-HDV2-2T1/E1. They ask me to be a network side and to provide
> clocking. I do the following:
>
> network-clock-participate slot 1
> network-clock-participate slot 2
>
> controller E1 1/0
>  clock source internal
>  pri-group timeslots 1-31
> !
> controller E1 1/1
>  clock source internal
>  pri-group timeslots 1-31
> !
> controller E1 2/0
>  clock source internal
>  pri-group timeslots 1-31
>
>
> L2 us up, L3 is up (calls initiate) but unfortunately on both sides we
> see slips. I don't get any clocking from line, so I cannot use
> "network-clock-select". Here is one "show":
> Router#sh network-clocks
>  Network Clock Configuration
>  ---------------------------
>  Priority      Clock Source    Clock State     Clock Type
>    11          Backplane       GOOD            PLL
>
>  Current Primary Clock Source
>  ---------------------------
>  Priority      Clock Source    Clock State     Clock Type
>    11          Backplane       GOOD            PLL
>
> I have also tried to "no network-clock-participate slot 1 (and 2)" but
> still the same - slips. Is there anything else I could do to correct
> configuration and provide a proper clocking?
> Am I right that best practice would be if Nortel would be a clocking
> source as it gets clocking from PSTN?
>
> Thanks for any comments,
> Andrius
>
>
>
>
>
>
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