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New Member

cisco 1721.... How do I set this up?


New here. Please bear with me, I have been in computers as a career for 8 years, but I am new to cisco routers.

I am trying to configure this router. It is a 1721 with a wic t1-dsu card in it. What I would like to do is use the sdm to configure this thing, but I cannot get it to work. What do I need? I have it connected right now with the blue cable (serial on one end), and when I boot up the router and have hyper terminal up and connected, it goes through the boot process fine. I just have no understanding of the command line structure. Hence me trying to use the sdm.

Is there a default ip address that I can use with the sdm? How do you reset the router back to the defaults?

I have just taken over a network that the old network administrator walked out on. No documentation, nothing. So I am playing catch up. This router was sitting on the shelf, he said (before he left) that he was going to put this one on the network and replace the 1720 router that is in place now.

I am trying to learn this one so if the other one goes down, I have a spare to throw in place.

If anyone can help me out, I would greatly appreciate it.

Thanks in advance.


Re: cisco 1721.... How do I set this up?

to get the router to its default (factory) configuration use the resetting router technique described in the following link:

more 1721 links:

Overview -

Configuration Guides -

Troubleshooting -

(this technique will assist you in setting the router to a state where you can access the command line to update any IP or config)

if you need configuration help, please state what you want the router to do and the topology it is to be placed into and we can provide configuration examples you can use.

New Member

Re: cisco 1721.... How do I set this up?

Good links. Thanks. I appreciate it.

I am figuring that since it is a spare, what harm could be done by me. So over the last day, I have gone in an I am learning the cli commands and how everything works.

The 1721 has in slot wic 0, a wic 1enet card, and in slot wic 1, a wic 1dsu t1.

Basically, I just want the router for the connection to our t-1 line, and to have the firewall enabled. The t-1 coming in right now goes to our 1700 router. I would like to be able to configure this router to take the place of the 1700 in event of emergency, by duplicating as much as possible the 1700's settings on the 1721.

Plus I am trying to learn cisco routers. Big job for a learn as you go deal.

I have tried to go into the 1721 and set the ip address back to so as to use the sdm. But for some reason I still cant get it to work.

Any other info you guys and gals need to help me out, let me know what it is.



New Member

Re: cisco 1721.... How do I set this up?

To set the ip address on an interface try this:

conf t -->hit enter

int ser0 -->hit enter

ip address -->hit enter

exit -->hit enter

exit -->hit enter

wr -->hit enter

Now you will have to set your default-gateway as well after this, it looks like it may be

I hope this helps a little bit.

New Member

Re: cisco 1721.... How do I set this up?

I bought this book when I was studying for my CCNA and it is invaluble. I love it, I still use it till this day as a reference.

And at that price you cant go wrong.

It will only help with CLI though.

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