Here is how to config the cisco 67x's for static IP's in ppp mode.

      IMPORTANT: Before you begin configuring your modem, the DHCP client in the PC should be disabled and should be configured statically with one of your static IP's addresses from the assigned block with a subnet mask set to whatever your isp gave you. (DO NOT use your "gateway ip" which will be assigned to your cisco router)

Using the current User Guide for the Cisco 678, connect the 675 or 678 modem to a COM port on the PC.

Start the Hyperterminal program. Set the connection parameters for the program as provided in your manual. Be sure to disable any flow control

Enter the "exec" and the "enable" passwords (if set) and check that the software version is 2.4.6 for the 678. The factory defaults for these passwords are blank.

You will see the prompt CBOS#. CBOS stands for Cisco Broadband Operating System and the # sign indicates that the modem is in the "enabled" or "privileged" mode for accepting configuration commands.

Where it says TYPE, enter what is inside the quote marks but NOT the quotes Type "set nvram erase"

Type "write" This command, in combination with the previous one, erases all configuration commands from the non-volatile RAM.

Type "reboot" This causes the modem to reboot and come up with the default configuration. which is PPP mode.

upon reboot Enter the "exec" and the "enable" passwords again. You will see the prompt CBOS#.

Type "set nat disable" This disables Network Address Translation (NAT) so that private addresses cannot be routed by the 675 or 678.

Type "set dhcp server disable" This disables the 675 or 678 from acting as a DHCP server.

Type "set PPP wan0-0 ipcp 0.0.0.0" (zeroes and not the letter O.) This causes the modem to negotiate via PPP an IP address for the modem. The network has been configured by the engineers to send the second highest value via the PPP negotiation. This actually becomes the IP address of the Ethernet interface with NAT disabled.

Type "set ppp wan0-0 dns 0.0.0.0"

Type "set PPP wan0-0 login xxxxx" where xxxxx is your user name assigned by your ISP.

Type "set PPP wan0-0 password yyyyy" where yyyyy is the password initially assigned to you. IMPORTANT: The user name and password are case-sensitive.

Type "set PPP restart enabled" If for some reason the 675 or 678 goes "untrained" during a session, this will automatically attempt to re-train the unit until successful.

Type "set int eth0 address zzz.zzz.zzz.zzz" where zzz.zzz.zzz.zzz is the Gateway Address from your block of Static IP's

Type "set int eth0 netmask 255.255.255.xxx" where the xxx is the subnet mask number your isp gave you.

If the service is in CAP mode, Skip to the write step below.

If The service is in DMT mode, the Cisco modem needs the following commands as well:

Type "set int wan0-0 disable"

Type "set int wan0-0 vpi 0"

Type "set int wan0-0 vci 32"

Type "set int wan0-0 enable"

Type "write"

Type "reboot"

After reboot log in to the 675 or 678 with the exec and enable passwords.

Type "sh nat" Verify that NAT is turned off.

Type "sh dhcp server" Verify that the DHCP server is turned off.

Type "sh int eth0" The IP address of the Ethernet interface should be the IP that your ISP assigned to you for the "Gateway".