number of DSPs needed for 5 ISDN PRI interfaces on 2811 platform

Answered Question
Jan 23rd, 2009

Hi all!

I have one Cisco 2811 router as a VoIP gateway between Telco and my CCM.

Currently, there's one ISDN PRI over 1-port T1/E1 Multiflex Voice/WAN Interface Card. There is PVDM2-32 module also and everything works fine so far.

Now I need to connect to CCM the four additional ISDN PRI interfaces from telco.

My question is can I achieve it on this router with:

1. adding two 2-port T1/E1 Multiflex Voice/WAN Interface Cards and

2. upgrading to two modules PVDM2-64 in total?

or

maybe should I go with a new router (which is less desired solution)?

In other words, would it be a problem to have 5 PRI interfaces with 2x PVDM2-64 modules in total on 2811 platform. Would it be enough?

TIA

Zoran Milenkovic

Correct Answer by Paolo Bevilacqua about 8 years 1 month ago

I realized my mistake and corrected my reply.

The point is that if you don't have enough DSP, you cannot configure the PRI interface at all, so as I said either get a bigger router, or install an NM-HDV2-xx.

Correct Answer by Paolo Bevilacqua about 8 years 1 month ago

Hi, you cannot use only PVDM2 on 2811 for 5 x E1, because the the 2811 has only two PVDM2 slots, and you need 3.

5 x 30 = 150 channels, 2 PVDM2-64 makes only 128 channels.

So, eithjer replace the router with abigger one, or use the PVDM2 on borad in conjuction with an NM-HDV-xxx.

If you have service contract, you can use the online DSP calculator for this kind of things.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (2 ratings)
Loading.
Correct Answer
Paolo Bevilacqua Fri, 01/23/2009 - 03:16

Hi, you cannot use only PVDM2 on 2811 for 5 x E1, because the the 2811 has only two PVDM2 slots, and you need 3.

5 x 30 = 150 channels, 2 PVDM2-64 makes only 128 channels.

So, eithjer replace the router with abigger one, or use the PVDM2 on borad in conjuction with an NM-HDV-xxx.

If you have service contract, you can use the online DSP calculator for this kind of things.

mizoran78 Fri, 01/23/2009 - 03:30

Thanks for answering but 2811 has only two PVDM2 slots :( That means that I can have two PVDM2-64 modules at maximum!

So if I have 5 ISDN PRI interfaces, I am wondering would it be enough?

Can we assume those two PVDM2-64 modules as a kind of 80% coverage of ISDN interfaces by DSP resources or not? Somebody with experience in similar scenario?

Thanks,

Zoran Milenkovic

Correct Answer
Paolo Bevilacqua Fri, 01/23/2009 - 03:54

I realized my mistake and corrected my reply.

The point is that if you don't have enough DSP, you cannot configure the PRI interface at all, so as I said either get a bigger router, or install an NM-HDV2-xx.

mizoran78 Fri, 01/23/2009 - 04:03

That's exactly what I wanted to know!

Thanks!

Zoran Milenkovic

Actions

This Discussion