AJAZ NAWAZ Tue, 11/13/2007 - 02:04
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Hi Adam

Taken from:




Integrated services router with AC power, 2FE, 4 Interface Card Slots, 2 PVDM slots, 2 AIMs, and Cisco IOS IP Base Software



Interface Card Slots

• 4 slots; 2 slots support HWIC, WIC, VIC, or VWIC type modules

• 1 slot supports WIC, VIC, or VWIC type modules

• 1 slot supports VIC or VWIC type modules


So the answer to both of your qtn's in yes.



pls rate the post if it helped

allan.thomas Tue, 11/13/2007 - 02:30
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Unfortunately although the router platform is capable of supporting four E1 modules and two pvdm2-64, the actual hardware specifications cannot.

As you are already aware in order to support 120 G711 Channels you will require two pvdm2-64, however the hardware can only possibly support 3O voice channels.

Please be cautious of the fact that there is always an associated overhead with DSPs and CPU utilisation.

If you require this module density then I would strongly recommend at least a Cisco 2821 router, although the 2811 gateway can support 120 voice channels, it highly likely that the CPU will be exceeded in this case.

The 2821 also support 3 DSPs, therefore you can add additional hardware transcoding/conference resource if required.



ajames2007 Tue, 11/13/2007 - 04:57
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excellent thanks. Do you have the document this came from?


allan.thomas Tue, 11/13/2007 - 09:05
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This is the same link as posted by Ajaz.


You can also find the DSP calculator tool invaluable too. If you try to configure the 2801 with multiple E1s and try to specify more than 30 G711 calls you will actually receive a warning that it can only support 30 channels.



AJAZ NAWAZ Tue, 11/13/2007 - 05:07
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Thanks for that - learn something new everyday.

I found the reference which states this:

"Cisco 2801 Routers

Cisco 2801 routers use the following PVDMs:

•PVDM2-8 (1 DSP)

•PVDM2-16 (1 DSP)

•PVDM2-32 (2 DSPs)

•PVDM2-48 (3 DSPs)

•PVDM2-64 (4 DSPs)

Conferencing needs dedicated DSP resources. A DSP will support eight conference calls on a G.711 codec, or two conference calls on a G.729/G.711 configuration. (The PVDM2-8 will support four conference calls on G.711 or 1 conference call on G.729/G.711.) There is a maximium of eight participants per conference. Up to 30 conferencing calls can be supported on the Cisco 2801 routers.

When conferencing service resources have been allocated, the remaining DSPs can be allocated to the voice and transcoding service requirements. A DSP supports six transcoding channels. The Cisco 2801 router supports up to 30 transcoding channels.

DSP usage for voice channel allocation can be optimized by changing the codec complexity of the analog VICs.

With a medium-complexity codec configured:

•One DSP can serve eight analog voice ports.

With a high-complexity codec configured:

•One DSP can serve six analog voice ports.

After the DSP channels are assigned to all the analog cards, the remaining unused DSP resources will first be assigned to BRI ports and then assigned to T1/E1 channels. "


oh, btw congratulations on the slvr badge ; )


allan.thomas Tue, 11/13/2007 - 08:59
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Thanks Ajaz appreciate it, congrats yourself. Looks like a long push to the next badge though.. ;-)


AJAZ NAWAZ Tue, 11/13/2007 - 09:05
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yeh and what about the one after that :-o

that's for the 'Old Timers'



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