Multiple PRI lines on 3825

[Dmitry Podtikhov]

Hi

I've got a 3825 router running Cisco IOS 12.4(24)T connected to the pbx via PRI line. Hardware is VWIC2-1MFT-T1/E1 and PVDM2-64 onboard. This PRI line tends to be overloaded so we want to add another VWIC2-1MFT-T1/E1 card and PVDM2-64 resource to the gateway and configure trunk group on the pbx side. The question is whethter it is possible to group this E1s into one logical trunk group on the router and to reference this grouping in the dial-peers? (or should I use dedicated devices such as cisco universal gateways).

[paolo bevilacqua · Accepted solution]

Yes, it is perfectly possible.

[Dmitry Podtikhov]

Thank you for your reply. Could not find any cisco doc with configuration example.

As I can understand I'll need to

1) Create global trunk group

trunk-group PBX

2) Assign interfaces to trunk group

    interface  serial 0/0/0:15

    trunk group PBX

    interface serial 0/1/0:15

    trunk group PBX

3) Reference this group in the dial-peer

dial-peer voice 9 pots

dest-pattern 9......

trunk-group PBX

What about the DSP resources? Do I need to configure  them in some special way or it will be enough to physically insert the second module and it will work with my trunk-group automatically?

[acampbell · Accepted solution]

Hi,

Yes what you describe is  the way to implement trunk groups etc.

As far as DSP resources are concerned to run 2 PRI/E1s you would need at leat a PVDM2-64 or the equivelant like 2 x PVDM2-32 etc

The OLD DSP calculator for a 3825 is available at http://www.cisco.com/cgi-bin/Support/DSP/cisco_prodsel.pl

You will need CCO login credentials

The new DSP calculator includinfgthe ISR-G2 range like 20xx & 39xx is on

http://www.cisco.com/web/applicat/dsprecal/dsp_calc.html

HTH

Alex

[Dmitry Podtikhov]

I use G729a and my present DSP module can only handle 30 calls. I want to add another PVDM2-64 to increase the number of simultaneous calls to 60. (The DSP calculator suggest to add one PVDM2-48 + one PVDM2-8 though. This is unclear to me because for 30 G729a calls it suggests one PVDM2-64. So if I need to double the number of calls my understanding was that another PVDM2-64 is required)

Anyway, I've never used more than one DSP module so my question is whether I need to configure them in some special way or should they wok with my trunk group automatically?

[Chris Deren]

each g729 call will use 2 Pvdm channels, so simply do the multiplication.

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