Newbie: Cisco Routing Subnet Zero - Inconsistent Address and Mask

Discussion in 'Cisco' started by gseedy@hotmail.co.uk, Apr 11, 2005.

  1. Guest

    Hi All,
    Im new to cisco and I am trying to configure a new cisco 1721 router.
    My intention is to keep our 2 networks more or less seperate except to
    send small amounts of data to and from each other when necessary (i.e.
    keep network traffic seperate). One network is using the range
    192.168.1.1 - 192.168.1.254 with the sunet mask of 255.255.255.0 and
    uses a DHCP server. The other network, which hasn't been setup yet, I
    would like to use the range 192.168.2.1 - 192.168.2.254 with the same
    subnet mask of 255.255.255.0 but IP's will be statically assigned.

    I need the DHCP'ed PC's to be able to access the statically assigned
    PC's on the other network for data sharing.

    As I'm new to cisco I was hoping someone would be able to give me some
    pointers as to what needs to be configured on the router.

    So far what I have done is:
    Enabled fastethernet0 with a no shutdown command
    Issued ip subnet-zero command in the config section
    Set the ip address of the interface to 192.168.2.1 255.255.255.0
    'Tried' to map route to switch using 192.168.2.1 255.255.255.0
    192.168.2.2

    This last command fails and returns the message inconsistent address
    and mask. Whilst experimenting I got it to map successfully using the
    mask 255.255.255.255 but as I want both networks on the subnet
    255.255.255.0 I need to get it working with the other subnet.

    >From what I've read I understand that cisco, by default, does not allow

    zero subnets although a ip subnet-xero command show allow this. I've
    tried this and am still getting an inconsistent address and masak
    message.

    Anyone got any ideas??
     
    , Apr 11, 2005
    #1
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  2. RobO Guest

    Re: Newbie: Cisco Routing Subnet Zero - Inconsistent Address and Mask

    Hi,

    Looks to me like you are not putting the correct route statement in,
    however:

    If the networks 192.168.2.0 + 192.168.1.0 are directly connected to the
    router then you dont need to add a route statement.
    But if its not then your route statement would look like this:
    ip route 192.168.2.0 255.255.255.0 [interface]

    If you type:
    "show ip route"
    What is the output of the command.

    Do you have an extra WIC-1ENET on the 1721 and where is the switch
    connected to?

    Regards,

    Rob
     
    RobO, Apr 11, 2005
    #2
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  3. In article <>,
    wrote:

    > So far what I have done is:
    > Enabled fastethernet0 with a no shutdown command
    > Issued ip subnet-zero command in the config section
    > Set the ip address of the interface to 192.168.2.1 255.255.255.0
    > 'Tried' to map route to switch using 192.168.2.1 255.255.255.0
    > 192.168.2.2
    >
    > This last command fails and returns the message inconsistent address
    > and mask. Whilst experimenting I got it to map successfully using the
    > mask 255.255.255.255 but as I want both networks on the subnet
    > 255.255.255.0 I need to get it working with the other subnet.


    The "inconsistent address and mask" message means that the address part
    of a static route included some bits that are masked off by the mask.
    E.g.

    ip route 192.168.2.1 255.255.255.0 ...

    the .1 at the end of the address is masked off by the .0 in the mask.
    This is an error check that Cisco added, to catch cases where you used a
    too-large mask. The correct statement would be:

    ip route 192.168.2.0 255.255.255.0 ...

    But, as the other poster said, you don't need to create static routes
    for subnets that are ddirectly connected to the router.

    >
    > >From what I've read I understand that cisco, by default, does not allow

    > zero subnets although a ip subnet-xero command show allow this. I've
    > tried this and am still getting an inconsistent address and masak
    > message.
    >
    > Anyone got any ideas??


    You're not using the zero subnet, so why do you think this is relevant?
    In fact, you're not using *any* subnets, you're using ordinary class C
    address blocks.

    --
    Barry Margolin,
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
     
    Barry Margolin, Apr 12, 2005
    #3
  4. G Guest

    Thanks for your help. The main problem I was having was not knowing
    about the interface part of the ip route statement, and I was trying
    to figure out the ip address of the interface rather than the name.
    Anyhow, despite a crash of the IOS which had to be reinstalled, I have
    now got it working as I wanted it to be working.

    Thanks for your help.


    Barry Margolin <> wrote in message news:<>...
    > In article <>,
    > wrote:
    >
    > > So far what I have done is:
    > > Enabled fastethernet0 with a no shutdown command
    > > Issued ip subnet-zero command in the config section
    > > Set the ip address of the interface to 192.168.2.1 255.255.255.0
    > > 'Tried' to map route to switch using 192.168.2.1 255.255.255.0
    > > 192.168.2.2
    > >
    > > This last command fails and returns the message inconsistent address
    > > and mask. Whilst experimenting I got it to map successfully using the
    > > mask 255.255.255.255 but as I want both networks on the subnet
    > > 255.255.255.0 I need to get it working with the other subnet.

    >
    > The "inconsistent address and mask" message means that the address part
    > of a static route included some bits that are masked off by the mask.
    > E.g.
    >
    > ip route 192.168.2.1 255.255.255.0 ...
    >
    > the .1 at the end of the address is masked off by the .0 in the mask.
    > This is an error check that Cisco added, to catch cases where you used a
    > too-large mask. The correct statement would be:
    >
    > ip route 192.168.2.0 255.255.255.0 ...
    >
    > But, as the other poster said, you don't need to create static routes
    > for subnets that are ddirectly connected to the router.
    >
    > >
    > > >From what I've read I understand that cisco, by default, does not allow

    > > zero subnets although a ip subnet-xero command show allow this. I've
    > > tried this and am still getting an inconsistent address and masak
    > > message.
    > >
    > > Anyone got any ideas??

    >
    > You're not using the zero subnet, so why do you think this is relevant?
    > In fact, you're not using *any* subnets, you're using ordinary class C
    > address blocks.
     
    G, Apr 15, 2005
    #4
  5. rex.mbr

    Joined:
    Mar 25, 2009
    Messages:
    1
    (config)#ip route 213.180.127.0 255.255.255.240 83.99.240.121
    %Inconsistent address and mask

    Any idea?
     
    rex.mbr, Mar 25, 2009
    #5
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