3845 DSP Upgrades

Answered Question
Jul 28th, 2008

We have a spare 3845 that we plan to use in a future VoIP design. It was bought as a security router, so it came with no voice upgrades.

I've been researching what I need to do to upgrade it to support voice.

Our plan is to have three T1s coming in (one from Verizon for outbound calling, two from AT&T for inbound 1800#s). Total number of lines is 60, but I suppose we should plan for a max of 72.

We will be using G.722, which from my reading Cisco tells me is a Medium-Complexity Codec.

So I'll probably need three PVDM2-64? How are these installed on the router, and what is the max on a 3845? It looks like you actually install them on the network module, not the router itself?

Is there a network module that would include the DSPs, or do you always order it seperately?

And lastly, which network modules should I be looking at for voice T1s in my 3845?

Thanks!

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Correct Answer by Chris Deren about 8 years 4 months ago

To add to Deji's great response, the 3845 router has 4 on-board PVDM slots, each can accomadate up to 64 channel PVDM (PVDM2-64), the router also has 4 HWIC slot where you can insert VWIC2 cards (PRI cards). This solution will be cheaper than getting NM-HDV2 card, but either way will work just fine.

Besides voice termination, you may also want to configure resources for conferencing and/or transcoding. You can use the DSP calculator to come up with the appropriate modules.

HTH,

Chris

Correct Answer by Ayodeji oladipo... about 8 years 4 months ago

Hi,

To plan the number of dsps you need for your scenario, use the DSP calculator. This is a great tool from cisco to plan your dsp requirement.

Here is the link.

http://www.cisco.com/cgi-bin/Support/DSP/dsp-calc.pl.

PVDMs are installed in PVDM slots. These slots are located on the motherboard on the router.

Network Modules usually ship with DSPS, you dont have to order it seperately.

For network modules..

Have a look at this doc, it shows the available network modules and the DSPS that come with them.

http://www.cisco.com/en/US/tech/tk652/tk701/technologies_tech_note09186a00800b65d6.shtml

I did some configs for you..

If you are going to use HWIC cards eg 1 VWIC-2MFT-T1 and 1 VWIC-1MFT-T1 (total is 72 channels)

Then you will need...

9 DSP(s).

one PVDM2-16 + two PVDM2-64

or

three PVDM2-48

or

three PVDM2-32 + one PVDM2-48

This is based on medium complexity codec..

voice-card 0

codec complexity medium.

If you are going to use network Modules..

eg NM-HDV-2T1-48 in slot 1

and NM-HDV-1T1-24 in slot 2..

Then you do not need to buy additonla dsps as they dsps on this modules are self sufficient.

HTH, please rate useful posts

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Correct Answer
Ayodeji oladipo... Mon, 07/28/2008 - 06:10

Hi,

To plan the number of dsps you need for your scenario, use the DSP calculator. This is a great tool from cisco to plan your dsp requirement.

Here is the link.

http://www.cisco.com/cgi-bin/Support/DSP/dsp-calc.pl.

PVDMs are installed in PVDM slots. These slots are located on the motherboard on the router.

Network Modules usually ship with DSPS, you dont have to order it seperately.

For network modules..

Have a look at this doc, it shows the available network modules and the DSPS that come with them.

http://www.cisco.com/en/US/tech/tk652/tk701/technologies_tech_note09186a00800b65d6.shtml

I did some configs for you..

If you are going to use HWIC cards eg 1 VWIC-2MFT-T1 and 1 VWIC-1MFT-T1 (total is 72 channels)

Then you will need...

9 DSP(s).

one PVDM2-16 + two PVDM2-64

or

three PVDM2-48

or

three PVDM2-32 + one PVDM2-48

This is based on medium complexity codec..

voice-card 0

codec complexity medium.

If you are going to use network Modules..

eg NM-HDV-2T1-48 in slot 1

and NM-HDV-1T1-24 in slot 2..

Then you do not need to buy additonla dsps as they dsps on this modules are self sufficient.

HTH, please rate useful posts

shanepresley Mon, 07/28/2008 - 07:06

Thanks for the excellent reply. I was wondering about the HWIC (and motherboard DSP) vs Network Module options, and your post explained it perfectly.

Correct Answer
Chris Deren Mon, 07/28/2008 - 06:37

To add to Deji's great response, the 3845 router has 4 on-board PVDM slots, each can accomadate up to 64 channel PVDM (PVDM2-64), the router also has 4 HWIC slot where you can insert VWIC2 cards (PRI cards). This solution will be cheaper than getting NM-HDV2 card, but either way will work just fine.

Besides voice termination, you may also want to configure resources for conferencing and/or transcoding. You can use the DSP calculator to come up with the appropriate modules.

HTH,

Chris

Ayodeji oladipo... Mon, 07/28/2008 - 06:45

Chris, Thanks for the compliment. Just a quick question what is the different between VWIC cards and VWIC2 Cards

Chris Deren Mon, 07/28/2008 - 06:48

The VWIC2-MFT is either T1 or E1 card depending on card type configuraion, the 1st generation cards VWIC-MFT were either T1 or E1, so if you need to ship router from US to Europe for example and configure E1 PRI on it you had to purchase new hardware, with 2nd generation cards you only need to reconfigure the card type command. The price is the same so, why would you get 1st generation card :-)

Chris

Ayodeji oladipo... Mon, 07/28/2008 - 06:57

Chris, This is nice! I have actually been using the VWIC2 and setting the card type without knowing this difference.

Thanks! +5points for this

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