T1 Phsyical Layer Question

Z

z8z

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Jan 22, 2016
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I recently saw my first T1 installation, which is carrier I know nothing about, and I noticed there was a 56Kbps modem attached to a Cisco ISR via a serial cable which I assume was RS-232.

I'm just wondering what the function of 56Kbps modem is in a T1 setup and what a good starting point would be for learning more.

Thanks HF.
 
Chances are the 56K was a backup method for getting into the router if the T1 is down. We used to do something similar for our remote sites when I worked for a local datacenter. If the main link was down, we could still get into the routers and see why and troubleshoot.
 
Yes the 56k Modem is just that a modem connection to access the router. We also did similar for remotely accessing equipment that we lost access to.
 
This is normal. Pretty much any decent provider does this for dedicated service. Whether that be copper (T1,T3,etc) or fiber.
 
Thanks ryan, sinclair, deaedius, usr.

I did have a feeling that the role of the modem had something to do with redundancy.
 
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The general term used is "out of band management." The redundancy is purely for management of the router. We would typically combine a modem with a terminal sever, or better a combo device, to manage routers, firewalls and switches on the customer prem.
 
I know with my company most of our customers have some sort of dial backup. I know of one customer right off that has a Cisco router connected connected to a old dial-up modem. And, like other people said, it's for when the main connection goes down so the site can still function.
We also do a lot of wireless backup connections that do the same thing.
 
Thanks guys, lot of good keywords that are helping my search for knowledge.
 
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