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New Member

Internet DS3 on a 3640

Customer has an immediate need to implement a DS3. Has empty slots on

his 3640. One reseller recommends the NM-1T3/E3 (to ATT) while another

recommends the NM-1HSSI with a HSSI-to-BNC adapter cable. I've never

herard of such a cable. Can anyone verify the HSSI approach would work

(clear channel, cbit framing, IP only). Direct email would be appreciated at

New Member

Re: Internet DS3 on a 3640

I think the question you should be asking here is this:

What is the handoff from the carrier and the DS-3 CSU? Most common DS-3 CSUs are HSSI based interfaces for the hand-off to the router.



New Member

Re: Internet DS3 on a 3640

The handoff is an ATT control mux (not a csu) that has been equipped with

a BNC port (not hssi). The NM-1A-T3 card married up well, however ATT wants

a PPP interface and not an ATM interface. ATT suggested a PA-T3 card, however that's for the 7206 and not the installed 3640. One reseller is suggesting the NM-1HSSI card with this adapter cable, and I'm 99.999% sure

(no matter what the reseller says) that a passive hssi-to-bnc cable isn't going

to support the clock and other interface signals required by the hssi card. But,

didn't want to inject (another) personal opinion and further confuse the


New Member

Re: Internet DS3 on a 3640

I think you are bound to the fact that the modules for the 3600 at those speeds are only HSSI and not BNC. I can think of two things here.

#1. Can ATT swap out the MUX with one that has a HSSI interface to the router?

#2. If you did use the HSSI-to-BNC cable, why wouldn't the signalling work? An electric charge on a wire is an electric charge. As long as the cable was smart enough to know how the pinouts and conversions work, then it should suffice. Otherwise, I cannot imagine why anyone would make such a cable if it didn't work at layer 1. Given that I have never used such a cable could result in me being absolutely wrong too!



Re: Internet DS3 on a 3640

When we put up our ds3 to the internet the provider said the 3640 couldnt handle it, even though it had the interfaces. I cannot remember the details but cisco agreed that it would not work at full ds3 speed.

New Member

Re: Internet DS3 on a 3640

The one network module you listed will work fine with the service that AT&T is providing. The NM-1T3/E3 provides exactly the connectivity and protocols that the provider requires.

The only problem is that they do not list the 3640 as a supported platform. Which indicates that your customer needs to upgrade the router inorder to provide this connectivity. I did notice a couple of high end 2600's listed in the supported platform area.

One additional note, if you change providers and you don't need the control mux in the future, you can connect your DS3 coax directly into the network module. It gives you a little flexability for future configurations.

Good luck.

New Member

Re: Internet DS3 on a 3640

Cutover is now done. Reseller that recommended the NM-1HSSI with BNC

adapter cable was all wet and finally admitted he didn't rearch it. Tried the

NM-1T3/E3 in the 3640 even though some Cisco documents say it works but

others say its not supported... would not recognize the card regardless of

which IOS we used (inlcuding a late 12.2 version). Ended up swapping the

router for a 2691 with updated IOS, and the NM-1T3/E3 card worked fine.

Also found the cisco ios planning tool (hardware compat) does not include the

NM-1T3/E3 card for either the 2691, 3640 or 3660. Looks like its not quit up

to date. Thanks to everyone that replied!!!

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