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New Member

Part# NM-HDV2-2-T1/E1

Can this part number be used for the following options:

One T1 Port would be connected to PSTN, and

the other one would be connected to IP/WAN at the remote location.

I have a Call Manager running in HQ, and the remote locations will have IP Phones connected Centrall to Call Manager in HQ.

Both ports will have to convert IP Phone Packets to PSTN Digital Format, and IP/WAN HDCL/PPP Format respectively.

Regards,

7 REPLIES
New Member

Re: Part# NM-HDV2-2-T1/E1

We are using this device for both WAN and PSTN connectivity at a couple of small sites. If you're using MPLS, you may want to look at 12.4.7(b) which combines both voice and MPLS routing. The other card to consider is the NM-HD-2VE which has more capability down the road, and is more flexible. Also, if you're using an ISR (2800,3800) the HWIC slots appear to be more reliable than the NM modules. When you configure the timing, you'll need to use only 1 timing source for both ports. (Recent discovery when using a T3 that was timed from an internal source led to issues on the voice circuits)

New Member

Re: Part# NM-HDV2-2-T1/E1

Hello scirlincione,

Thanks for the Info. Yes, I am using ISR routers 3845/3825. If I go with 2-port HWIC Slot then can I use one port for PSTN, and the other one for IP/WAN carrying both Data and IP Voice Traffic. or

Do you suggest use separate card for both connectivity. Any Help will be appreciated.

Regards,

Silver

Re: Part# NM-HDV2-2-T1/E1

You can run one port for voice and one for data - a sample config would be like this -

network-clock-participate wic 0

network-clock-select 1 t1 0/0/0

!

controller t1 0/0/0

description - PRI voice connection

framing esf

linecode b8zs

pri-group timeslots 1-23

!

controller t1 0/0/1

description - data connection

framing esf

linecode b8zs

channel-group 0 timeslots 1-24 speed 64

...

interface serial 0/0/0:23

description - connection to PBX

isdn switch-type primary-ni

isdn incoming-voice voice

!

interface serial 0/0/1:0

description - data connection to remote site

ip address 10.1.1.1 255.255.255.0

!

New Member

Re: Part# NM-HDV2-2-T1/E1

Is this really valid? According to documentation you can not share voice and data on a single VWIC module because each VWIC only supports a single clocking domain (or 2 for data). So it appeared that Voice/Voice is ok, and Data/Data, but not Voice/Data on one card. How is the clock being handled for the data and voice circuits in this scenerio?

Cisco Employee

Re: Part# NM-HDV2-2-T1/E1

The above config assumes the voice and data are in the same clocking domain. If the two services come from the same provider, then they generally are.

If they come from different vendors, we quite often see clock slips on one of the interfaces due to the sligh timing differences. In this case, you have to decide which interface can handle the errors better - in many cases you have to put up with what are essentially controlled slips on the data interface (since the majority of data apps are generally more resilient to the odd error that voice/fax/modem services).

The later model VWIC2 cards actually allow data interfaces to run independantly to a voice port, so the router backplane derives clocking from the voice interface and the data interface is in it's own local clocking domain.

Refer here for some more details -

http://www.cisco.com/en/US/docs/ios/12_2/12_2z/12_2zj/feature/guide/gthwecan.html#wp1068593

The independent keyword expands on the clock source internal and clock source line to specify that the port can operate on an independent clocking domain. Port 0 is the default primary clock source, and port 1 is the default secondary clock source and is loop-timed. With independent clocking enabled, this dependency no longer exists, so the independent keyword means that both ports can be independently clocked.

Note When independent clocking is configured, the controller will support only one channel group and no voice applications.

If more than one channel group is configured, the following error message occurs:

channel-group 2 timeslots 3

%Channel-group already created.

%Only 1 channel-group can be configured with

independent clocking.

%Insufficient resources to create channel

group

When you are configuring the clock source independent and no clock source independent, the channel group has to be removed from this configuration.

New Member

Re: Part# NM-HDV2-2-T1/E1

Thanks, this was my understanding. Lets say you have a 2-port VWIC and voice in port 0 and a point to point data T1 in port 1. You take clock off the voice as to avoid any slips. Can't you run the port 1 to use the clock off the voice port, and then run the far side of the PtP to recover clock from the line, so that this way slips can be avoided?

I thought about this, but everywhere I see point to points there is telco in the middle and a clocking is typically taken from the line on both sides, so I think that may screw it up.

Cisco Employee

Re: Part# NM-HDV2-2-T1/E1

You can derive clock off the first port and use this recovered clock to drive the second port. As you have pointed out, if you can then have the far end data connection synchronise off the clock the t1 card sends out, then it will all be sweet and as there is a common clock reference, there will not be any slips observed,

However ... most data connections are ultimately derived from a large carrier network and therefore it is difficult to convince them to accept clocking from the CPE.

In these situations, it is often better to use a single port VWIC for the voice connection and another single port VWIC for the data connection - this way each card can be in it's own clocking domain.

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