Cisco 1812 subnet to subnet NAT

Discussion in 'Cisco' started by Amadej, Sep 3, 2007.

  1. Amadej

    Amadej Guest


    I'm a bit new to Cisco router configurations and I'm wondering if it
    is possible to specify a 1-1 NAT for whole subnets. I'd like our
    internal address range (let's say to be
    translated to our external address range (let's say
    x.x.x.1/ - but I can't find a way to configure the
    router to do this apart from entering static NAT rules for each IP
    translation (and there is apparently a 100 rule limit on the

    Basically I want to be translated to x.x.x.1 and to
    x.x.x.2 and so on.

    From what I understand I can't do it with dynamic NAT and address
    pools because I have no way of controlling which internal IP gets
    which external IP?

    So how does one insert a static 1-1 NAT for a whole address range? All
    I found were commands for a static 1-1 IP to IP nat.

    Thanks in advance!
    Amadej, Sep 3, 2007
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  2. Amadej

    Merv Guest

    Match Host

    The ability to configure NAT to assign the same Host portion of an IP
    Address and only translate the Network prefix portion of the IP
    Address. Useful where you are using the host portion as a means to
    identify or number users uniquely.

    Host Number Preservation:

    For ease of network management, some sites wish to translate prefixes,
    not addresses. That is, they wish the translated address to have the
    same host number as the original address. Of course, the two prefixes
    must be of the same length. This feature can be enabled by configuring
    dynamic translation as usual, but configuring the address pool to be
    of type "match-host":

    ip nat pool fred <start> <end> prefix-length <len> type match-host
    Merv, Sep 4, 2007
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