No announcement yet.

How to make Cisco 2811 public ip the same as internal ip

  • Filter
  • Time
  • Show
Clear All
new posts

  • How to make Cisco 2811 public ip the same as internal ip

    I have a new cisco 2811 router with a CSU card on it, this unit will replace an existing 2500 router which is running like this :

    T1 ----> 2500 (12.118.xx.70) ----> ETHE 0/0 (12.xx.xx.73 ) --->Unix server (12.xx.xx.78 ) public address
    ETHE 0/1 (12.xx.xx.65 )----> Voip Patton smartnode ( 12.xx.xx.66) public address

    The gateway is 12.xx.xx.65
    The Current Ethernet 0/0 is setup as 12.xx.xx.73
    Ethernet 0/1 is setup as 12.xx.xx.65
    The current serial 0/0 is setup as 12.118.xx.70

    So any user over the internet does 12.xx.xx.78 and gets into my unix server (email,web,ssh,etc)
    And remote smartnodes connect to 12.xx.xx.66 to my local smartnodes

    I tried copying the same configuration to the new 2811 by doing a "show configuration on the old 2500" but the public ip addresses .78 and .66 are not working when I try to access them from the internet, Could you please tell me if on the 2811 I have to set NAT ?

    If I'm on the CLI on the 2811 I'm able to traceroute to the 12.xx.xx.78 and traceroute to the outside world. I'm able from the outside world to see my router if I use the 12.118.xx.70 address.

    From the unix server I can log in into the 2811 when I do 12.xx.xx.73 but that's about it. Do I need a bridge to make my internal IP's outside IP's ?

    My firewall is OFF .

    Please help.
    Last edited by henry1970; 3rd June 2007, 21:50.

  • #2
    Re: How to make Cisco 2811 public ip the same as internal ip

    Hi henry,

    Sorry that no one has gotten back to you on this. Have you been able to solve this since then?

    Here are my two cents-

    No, as there are PUBLIC IPs on each side of the router, the router does not do NAT or bridging - it is routing.

    The config between the 2500 and 2800 should be almost identical but the interface numbers will have changed.

    If you are still having this problem, please post your config.

    Are there any ACLs on the 2500?

    David Davis - Petri Forums Moderator & Video Training Author
    Train Signal - The Global Leader in IT Video Training - Free IT Training Products
    Personal Websites: &