pvdm?

itdaddyitdaddy Senior MemberMember Posts: 2,089 ■■■■□□□□□□
do I need a pvdm for fxo and fxs cards?

Okay I am goingto buy 2 x fxs cards for my cisco 1760 routers to hook up
2 pots phones
and I am buying 1 x fxo card

so then I would need 3 x pvdms????

thanks

Comments

  • hypnotoadhypnotoad Banned Posts: 915
    itdaddy wrote: »
    do I need a pvdm for fxo and fxs cards?
    Okay I am goingto buy 2 x fxs cards for my cisco 1760 routers to hook up
    2 pots phones
    and I am buying 1 x fxo card
    so then I would need 3 x pvdms????
    thanks

    No, you need basically one or two PVDM's capable of running 3+ channels. The 1760 has two slots I believe.

    Cisco 1751 and Cisco 1760 routers use the following PVDMs (http://www.cisco.com/en/US/docs/routers/access/1700/1751/software/feature/guide/dsp_cn.html):
    •PVDM-256K-4 (1 DSP)
    •PVDM-256K-8 (2 DSPs)
    •PVDM-256K-12 (3 DSPs)
    •PVDM-256K-16HD (4 DSPs)
    •PVDM-256K-20HD (5 DSPs)

    The number on the end is the number of channels it will run. So a -4 would run 4 channels. You might ask, when would I need 12 or more channels in my 1760? Well, while analog wic cards are just a couple channels, a T1 is ~24 channels.

    Also, one DSP can serve 4 analog voice ports. So you have to take number of DSPs in to account as well as number of channels.

    Hope this helps,
    HT

    By the way, this is all assuming you run plain old G.711 codec, if you have to convert between codecs ("transcoding"), it will use more resources, but that can be easily calculated and accounted for. Google "cisco dsp calculator".
  • itdaddyitdaddy Senior Member Member Posts: 2,089 ■■■■□□□□□□
    wow HT you are the man. like why arent you CCVP yet? haha
    thanks so much man happy new year. this helps a lot thank yuo
    getting my voip lab up and running soon this year :)
  • hypnotoadhypnotoad Banned Posts: 915
    itdaddy wrote: »
    wow HT you are the man. like why arent you CCVP yet? haha
    thanks so much man happy new year. this helps a lot thank yuo
    getting my voip lab up and running soon this year :)

    Personally...

    I found out I never passed a Cisco exam unless it's been something I've had to use in the real world - no matter how much labbing. I realized this, and then remembered we were an Avaya shop, and gave up. icon_sad.gif
  • itdaddyitdaddy Senior Member Member Posts: 2,089 ■■■■□□□□□□
    hypnotoad
    funny you should mention that....we are a Mitel shop but use cisco for some QOS stuff..my lab I hope to be full fledge lap with CUCM in the form of a VM.
    but I do know what you mean though...I am going to try.but it is always nicest to have real world experience along with....you are right it is a lot harder..
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