reserved addresses

Discussion in 'Cisco' started by ciscortp, Jun 4, 2006.

  1. ciscortp

    ciscortp Guest

    Is it possible to create a loopback address as 192.168.1.255 /32 Or
    is the .255 always reserved?

    If this is Not allowed can you please try to enter this (into a cisco
    router ) and paste the router output error message.

    Thank you
     
    ciscortp, Jun 4, 2006
    #1
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  2. Is it possible to create a loopback address as 192.168.1.255 /32 Or
    All valid class a,b or c addresses are allowed...

    rtr#conf t
    Enter configuration commands, one per line. End with CNTL/Z.
    rtr(config)#int lo99
    rtr(config-if)#ip address 192.168.1.255 255.255.255.255
    rtr(config-if)#
    rtr(config-if)#ip address 0.0.0.0 255.255.255.255
    Not a valid host address - 0.0.0.0
    rtr(config-if)#
    rtr(config-if)#ip address 1.0.0.0 255.255.255.255
    rtr(config-if)#
    rtr(config-if)#ip address 1.0.0.255 255.255.255.255
    rtr(config-if)#
    rtr(config-if)#ip address 1.255.255.255 255.255.255.255
    rtr(config-if)#
    rtr(config-if)#ip address 0.0.0.1 255.255.255.255
    Not a valid host address - 0.0.0.1
    rtr(config-if)#ip address 255.0.0.1 255.255.255.255
    Not a valid host address - 255.0.0.1
    rtr(config-if)#

    As long as they don't overlap with other interfaces..

    rtr(config-if)#ip address 192.168.24.99 255.255.255.0
    % 192.168.24.0 overlaps with Ethernet0
    rtr(config-if)#
    rtr(config-if)#ip address 192.168.24.99 255.255.255.255
    % 192.168.24.99 overlaps with Ethernet0
    rtr(config-if)#

    And as long as it is not the network or broadcast address for the mask
    chosen:

    rtr(config-if)#ip address 10.0.0.255 255.255.255.0
    Bad mask /24 for address 10.0.0.255
    rtr(config-if)#
    rtr(config-if)#ip address 10.0.255.255 255.255.0.0
    Bad mask /16 for address 10.0.255.255
    rtr(config-if)#
    rtr(config-if)#ip address 10.0.255.254 255.255.0.0
    rtr(config-if)#
    rtr(config-if)#ip address 10.0.0.0 255.255.0.0
    Bad mask /16 for address 10.0.0.0
    rtr(config-if)#
     
    Joop van der Velden, Jun 4, 2006
    #2
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  3. You can not confugure an IP address with all "1s" in the host portion of
    address. It's reserved for "broadcast" address, same way as all "0s"
    reserved for "network address". And even with the fact that you may be able
    to configure this address, you will be unable to do anything with it.

    Good luck,

    Mike
     
    HeadsetAdapter.com, Jun 4, 2006
    #3
  4. There are special rules for /31 and /32, especially in connection
    with point-to-point links.
     
    Walter Roberson, Jun 5, 2006
    #4
  5. ciscortp

    thrill5 Guest

    Yes it is. All of our routers use a /32 for their loopback addresses.

    Scott
     
    thrill5, Jun 6, 2006
    #5
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