>In short: Can I hook a 56k DSU that seems to have a serial interface to a
>Linux box and use the Linux box as a router to replace my dead Cisco?
>In longer format:
>I have a Cisco 2501 that died the other day. I need to get something running
>in a hurry. I'd love to replace it with Linux, and show the people in higher
>places in my company how cool Linux is, and how cool I am. <G>
>Anyhow, I need to connect a linux box to an Adtran DSU 5600, which is a 56k
>DSU that seems to have a serial connection. The label above the db25 port on
>it is "EIA-232", which, when I looked it up, is short for Electronics
>Industry Association, or something like that, anyway, it's equivalent to
>When I look at the pinout for this DSU and compare it to the pinout for an
>external modem, everything is the same except for two pins. Those two pins
>On the DSU:
>15 Transmit Clock (SCT)
>17 Receive Clock (SCR)
>22 Ring detect
>Do I need to make a cable that uses SCT/SCR, possibly in replacement of
>DTR/Ring? What kind of software do I need to use?
>When querying the Cisco, it says that it's setup with PPP encapsulation to
>the outside world (thru the DSU), and the serial interface that the DSU is
>connected to has no IP address. I plugged the DSU into the linux box as if it
>were a modem, and ran pppd as if there was a modem connected to that port.
>The DSU lights up a few lights for a few seconds, during which pppd is still
>a running process. Then, after those mayb 5 or 10 seconds go by, the pppd
>process is terminated and the lights on the DSU go off.
>Please, any help would be appreciated, especially if you can tell me how to
>make it all work. I looked thru all the FAQs and HowTos on
>http://www.linux-howto.com and didn't find anything relevant, but if you know
>of a faq or howto that pertains to me, please, feel free to point me at it.