Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Cisco 1721 Router Need quick help please

Howdy. I am very new to the wonderful (but advanced) Cisco world. My 1721 router was configured a long time ago and has been working perfectly for many years, but a few days ago we changed our ISPs and now I need to enter in new IP information for my new ISP and have no idea where to start.

I have the console cable hooked up to the back of the router in the console port, going to my laptop with windows XP.

I am guessing I start hyper terminal, but have no idea what to do next. Can anyone help me step my step on what to do. I have been reading and reading, but get lost as soon as the manual tells me to put router > enable.

I am sure to some of you, you have memorized the few commands it will take to change the wan infomartion and if you can share it that would be amazing, and if I have to pay for some info, I dont mind that either, just hoping someone can take mercy on me and help me, my business is dieing with no internet. Thanks a lot


Re: Cisco 1721 Router Need quick help please

Start Hyper Terminal

You'll be prompted to name a new connection. Name it anything you want.

In the next window drop down the "Connect Using" box and select the com port that is connected from your PC to the Router.

In the next window match these settings...

Bits per second: 9600

Data bits: 8

Parity: None

Stop bits: 1

Flow Control: Hardware

Hit enter till you get some output on the screen. What happens next depends on how the Router is configured. If prompted, enter your credentials (Hopefully u know them). If it takes you straight to this prompt Router> type enable and hit enter. you'll either go straight to this prompt Router# or you'll be prompted for credentials.

Once you get to the enable prompt Router# enter the sh run command. Post the output here. Be sure to remove passwords, public IP addresses, and any other sensitive data before posting.


New Member

Re: Cisco 1721 Router Need quick help please

Thank you sooo much for your quick reply, I knew I had come to the right place for help. 

I appreciate your help, the only problem is that when I actually physically get to the router, I will have about one hour or so to solve this, and don't think I would have the chance to go back and work on it for a second time. That's why I was trying to gather as much information I possibily could before I went out to the router. If this is not possible, and I must do what you said and post the results, then I have no choice, but if there was additional information you could give me that would maybe get me a little further, and I would be able to piece things together, that would be great too.

Regardless, thanks for taking your time to help me out, I really appreciate it. I will be looking forward to your response

Hall of Fame Super Gold

Re: Cisco 1721 Router Need quick help please

Why don't you engage a true network enginner for the job ? Won't cost much and you will be guarantted it will be made properly and professionaly.

Re: Cisco 1721 Router Need quick help please

Roger that.


There are so many possible variables to consider. If you are lucky all you'll have to change is an IP address and a default gateway. If the Router has been setup well you'll likely need to change ACL's etc... If you're new to ACL's this wouldn't be the ideal time to start playing with them.


CreatePlease to create content