I checked your configuration, what we have there is a Slip prone setup
> for sure, slips will not affect voice calls but
> faxes and modems will not work since they might report a poor line
> condition, on this setup we have data T1s coming from a
> different clocking than the clocking that comes on the voice lines -
> even worst I'm not taking into consideration
> that the data lines might not be coming from the exact same router
> therefore they might not be the exact same clocking
> same thing for the voice lines, we do not know if they come from the
> same Telco switch therefore they might not have
> the same clocking - we will need to isolate clocking domains by adding
> Network modules for each different clocking coming into the router,
> the following might clarify how clocking deploments must be done to
> avoid slip errors.
>
> Here's a small diagram of the 2800s and 3800s architecture
>
> ******************************************************* <<< Motherboard
> * HWIC-----\ *
> * HWIC----------------TDM Bus-----DSPs *
> * HWIC-----/ *
> *******************************************************
>
>
> The TDM bus takes care of taking the clocking from one T1 (main clock
> source) and pass
> that clocking to any other controller that is configured as internal
> in order to spread
> the clocking coming in from the main source to any other device
> connected to the router that might require clocking,
> a clocking domain must have only one source of clocking coming into
> the router.
>
> The Chassis has its own clocking domain and a voice network module can
> have its own
> clocking domain as well.
>
> Clocking Problems:
>
> Router
> |----------------|
> Clock1====T1===|>> Clock1 coming in
> | TDM Backplane
> Clock2==T1=====|>> Clock2 coming in
> |----------------|
>
>
> As I mentioned we must have only one clock coming into the router, all
> the HWICs on the
> chassis conform the motherboard clocking domain, a set up like this
> will give us Slip
> errors for sure, since we have two different clocks coming into the
> router.
>
>
> Router
> |----------------|
> |====T1===|>> Clock1 coming in
> Clock1 | TDM Backplane
> |====T1===|>> Clock1 coming in
> |----------------|
>
> As you can see it is the same clock coming into the router, since the
> source of the
> clocking is the same, then no Slips appear.
>
> Router
> |----------------|
> Clock1==T1==|>> Clock1 coming in
> | TDM Backplane
> Clock2==T1==|>> Clock2 coming in
> |----------------|
>
> This set up will have slip errors, the point is that we must keep a
> unified
> clocking terminating on the VWICs installed in the chassis, since all
> the HWICs belong to
> the clocking domain.
>
> Solutions:
>
> Split the clocking domain by using a Voice Network module like an
> NM-HDV with a
> VWIC-2MFT-T1, clock2 will terminate clocking on the NM and clock1 will be
> terminating clocking on the chassis, therefore they would be on
> different clocking domains
> and no Slip errors would occur since each clocking domain will contain
> its own different
> clock source.
>
> Router
> |----------------|
> Clock1===T1====|>> Clock1 coming in
> | TDM Backplane
> |----------------|
> | NM TDM backplane
> Clock2==T1======|>> Clock2 coming in
> |-----------------|
>
> On this case we won�t have Slip errors since the 2 different clocks
> will go
> to different clocking domains.
>
> You can also find this explained on the book: "Cisco Voice Gateways
> and Gatekeepers" page 195.
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