View source for KB 104

===How do I set up a Cisco 675 or 678 router to use a routed subnet
(instead of NAT)?===
 Article:104
 Created:2002-07-16 18:02:51
 Categories:
   routing
   DSL

====Question or Symptom====
How do I set up a Cisco 675 or 678 router to use a routed subnet
(instead of NAT)?


====Resolution====
Once you flush the NVRAM, you will need to access the Cisco via a blue
management cable connected to the serial port on your computer.
  
To set the unit up for PPP mode we first need to flush the NVRAM. Type the 
following:
        enable
        set nvram erase
        write
        reboot
  

This takes a minutes to reboot. Next we'll set up PPP.  Use your email account
login and password on the "login" and "password" lines.
  
        enable
        set ppp wan0-0 ipcp 0.0.0.0
        set ppp wan0-0 dns 0.0.0.0
        set ppp wan0-0 login Your_Email_Login
        set ppp wan0-0 password Your_Email_Login_Password
        set ppp restart enabled
        set dhcp server enabled
        set nat disable
        set interface vip0 ip <ethernet_ip_of_cisco>
        set interface vip0 mask <subnet_mask_of_cisco>
  
The "dhcp" lines are optional.  Only use them if you want the Cisco 675 to
be your DHCP server.  If you have another DHCP server on your LAN or if
you assign static IPs to your machines, then you don't need to set up DHCP.
  
        set dhcp server pool 0 ip <pool_start_addr>
        set dhcp server pool 0 netmask <pool_mask> 
        set dhcp server pool 0 gateway <ethernet_ip_of_cisco>
  
If you have a 678 and your DSL protocol is DMT instead of CAP (all new Qwest
DSL circuits after April, 2001 are DMT), then you need to enter these additional
commands:
  
    set interface wan0-0 disable
    set interface wan0-0 vpi 0
    set interface wan0-0 vci 32
    set interface wan0-0 enable
  
Next, save the new configuration and reboot the router:
  
        write 
        reboot
  
At this point any passwords you previously set will be gone, so you'll want
to set a login and enable password. Please don't lose these!
  
         enable
         set password exec Your_Exec_Password
         set password enable Your_Enable_Password
         write
  

Here is a specific example of what the "interface" and "dhcp" lines might look
like.  This is assuming a subnet of 216.184.23.16/29, with IP address
216.184.23.17 assigned to the router, and addresses .18 through .22 assigned
via DHCP:
  
        set interface vip0 ip 216.184.23.17
        set interface vip0 mask 255.255.255.248
        set dhcp server pool 0 ip 216.184.23.18
        set dhcp server pool 0 netmask 255.255.255.248
        set dhcp server pool 0 gateway 216.184.23.17


====Related KB articles====
  [[KB 81]] How do I configure my Cisco 675 or 678 for Megabit service?

  [[KB 94]] How does one set up port forwarding on the Cisco 675 router?

  [[KB 95]] How does one change the internal IP address of the Cisco 675 router?