Cisco 678 Subnet

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DSL Configuration for Cisco 678 in PPP (DMT), Multiple IP Addresses

Before you begin, you will need connect the management serial cable that came with your 678. It will need to be connected to the "MGMT" port on the back of the 678 and a serial port on your computer. You will then need to connect to the 678 with terminal software (e.g.: Hyperterminal, ZTerm, Minicomm, Telix). The speed the terminal software will communicate with the 678 will be either 9600 or 38400, no software or hardware handshaking.


  1. At the [Password] prompt, hit the Enter key.
  2. Type "enable" and hit the Enter key twice.
  3. show version
  • Note: The Cisco 678 requires v2.4.0 or higher for proper PPP operation. XMission

recommends v2.4.3. This is available for customer FTP by logging into "ftp.xmission.com" with customer's account and password then changing to the "/archive/dsl" directory. Instructions for upgrading are contained within the README file.

  1. set nvram erase
  2. write
  3. reboot
  • Note: The 678 will reboot and bring you back to a "Password" prompt.
  1. Press Enter.
  2. Type "enable" and hit the Enter key twice.
  3. Set interface wan0-0 disable
  • Note: Some versions require "set interface wan0-0 close".
  1. set interface wan0-0 vpi 0
  2. set interface wan0-0 vci 32
  3. set interface wan0-0 enable
  • Note: Some versions require "set interface wan0-0 open".
  1. set web disabled
  2. set web port 8081
  3. write
  4. reboot
  • Note: Again, the 678 will reboot and bring you back to a "Password" prompt.
  1. Press Enter.
  2. Type "enable" and hit the Enter key twice.
  3. set ppp wan0-0 ipcp 0.0.0.0
  4. set ppp wan0-0 login acctname (where acctname is your XMission username)
  5. set ppp wan0-0 password mypasswd (where mypasswd is your XMission login password)
  6. set ppp restart enabled
  7. set bridging rfc1483 off
  8. write
  9. reboot
  • Note: The 678 will, again, reboot.
  1. Press Enter.
  2. Type "enable" and hit the Enter key twice.
  3. set nat disabled
  4. set interface eth0 address x.x.x.x (where x.x.x.x is the first usable IP in your subnet)
  5. set interface eth0 netmask 255.255.255.x (where 255.255.255.x is your subnet mask)
  • Note: To calculate your subnet mask, subtract the number of IP addresses in your

subnet from 256. The result is the last number of your subnet mask. For example, if you have 8 IP addresses, subtract 8 from 256. The resulting subnet mask is 255.255.255.248.

  1. set password exec myexecpw (where myexecpw is any password you choose)
  2. set password enable myenablepw (where myenablepw is any password you choose)
  • Note: CBOS version v2.4.0 will not allow telnet from any source until passwords

have been set for both "exec" and "enable" modes. Earlier versions allow telnet, and in fact will allow any access to its configuration unless password protected. In both circumstances, XMission recommends you set passwords for your router.

  1. write
  2. reboot