Configuring CISCO 1720 Router...

Posted on 2006-05-15
Last Modified: 2012-05-05
I have a Cisco 1720 Series router that I need help programming.  I am very new to Cisco products, so please bare with me.


1.  I do not know the password to access it via the management console, so that is my first question:  How can I reset the router with a new password?

2.  I know for certain the router was programmed in a "pass through" manner with no firewall or access list features enabled. So, basically, the WIC and Ethernet ports are programmed to hand off a T1 line to the ethernet.  I need to change the WIC IP info and the Ethernet info.

I am under a strict deadline [I know, aren't we all] and this project was just handed to me.  ANY HELP IS GREATLY APPRECIATED.

Here is my show ver details

Cisco Internetwork Operating System Software
IOS (tm) C1700 Software (C1700-Y-M), Version 12.1(8c), RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Fri 08-Feb-02 17:57 by shawnk
Image text-base: 0x80008088, data-base: 0x805ED0F8

ROM: System Bootstrap, Version 12.0(3)T, RELEASE SOFTWARE (fc1)

ExpressOne uptime is 1 hour, 4 minutes
System returned to ROM by power-on
System image file is "flash:c1700-y-mz.121-8c.bin"

cisco 1720 (MPC860) processor (revision 0x601) with 24576K/8192K bytes of memory
Processor board ID JAD06070D5V (417516928), with hardware revision 0000
M860 processor: part number 0, mask 32
Bridging software.
X.25 software, Version 3.0.0.
1 FastEthernet/IEEE 802.3 interface(s)
1 Serial network interface(s)
32K bytes of non-volatile configuration memory.
8192K bytes of processor board System flash (Read/Write)

Configuration register is 0x2102
Question by:Yort
    LVL 9

    Expert Comment

    Here's an instruction on how to do password recovery on the 1720.

    Recovering a Lost Password
    LVL 5

    Accepted Solution

    The WIC is probably listed as interface Serial0/0/0.

    The commands to change the IP address would be:

    Router#conf t
    Router(config)#itn Serial0/0/0
    Router(config-if)#ip address

    The ethernet interfaces would be as follows:

    Router#conf t
    Router(config)#itn fa0/0
    Router(config-if)#ip address

    This would change the IP addresses, but you would potentially need to change your routing commands so that traffic would be routed to the correct interfaces. Once you access your router, use the "show ip route" command and display your routing information and I or another member could aid you in making the correct changes.


    LVL 2

    Expert Comment

    I'm assuming you are using this as a gateway router to connect to your ISP? If so after programming the IP addresses add the line:

    ip route  X.X.X.X

    With X.X.X.X being the gateway IP of your ISP. This tells the router to send all triffis to IPs it doesn't know to go to the ip address X.X.X.X
    LVL 12

    Expert Comment

    If it's a 1720, the serial should be Serial0, not Serial0/0/0.

    You'd be safer with ip route Serial0 instead of ip route x.x.x.x.

    Write Comment

    Please enter a first name

    Please enter a last name

    We will never share this with anyone.

    Featured Post

    Why You Should Analyze Threat Actor TTPs

    After years of analyzing threat actor behavior, it’s become clear that at any given time there are specific tactics, techniques, and procedures (TTPs) that are particularly prevalent. By analyzing and understanding these TTPs, you can dramatically enhance your security program.

    New Server  was moved from behind Router R2 f0/1 to behind router R1 int f/01 and has now address But we want users still to be able to connected to it by old IP. How to do it ? We can used destination NAT (DNAT).  In DNAT…
    I recently attended Cisco Live! in Las Vegas, a conference that boasted over 28,000 techies in attendance, and a week of hands-on learning hosted by a solid partner with which Concerto goes to market.  Every year, Cisco displays cutting-edge technol…
    After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
    After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

    760 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    7 Experts available now in Live!

    Get 1:1 Help Now