BGP mask

Discussion in 'Cisco' started by ciscortp@hotmail.com, May 30, 2006.

  1. Guest

    Can someone explain the reason for NOT using the "mask" keyword in a
    BGP network statement? Ie.

    Router bgp 65010
    Network 1.1.1.1

    VS.

    Router bgp 65010
    Network 1.1.1.1 mask 255.255.255.0

    Thanks,
     
    , May 30, 2006
    #1
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  2. Guest

    when you dont "no auto-summary" and want to announce 1.0.0.0/8
     
    , May 30, 2006
    #2
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  3. Guest

    wrote:
    > when you dont "no auto-summary" and want to announce 1.0.0.0/8


    Could you please clarify this answer? I don't understand your response

    Thank you
     
    , Jun 2, 2006
    #3
  4. Gararda Guest

    Hy,


    If you are using the "no auto-summary" keyword:

    -You must have a exact match in the IP routing table to appear the
    network in the BGP routing table. For example:
    - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
    appear in the IP routing table.
    - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
    appear in the IP routing table.


    If you are using the "auto-summary" keyword:

    -You must have the classfull network or a subnet of this classfull
    network in the IP routing table to appear the network in the BGP
    routing table. For example:
    - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
    or 1.1.1.1/10.... exist in the IP routing table.
    - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
    or 1.1.1.1/26.... exist in the IP routing table.

    CIAO

    wrote:
    > Can someone explain the reason for NOT using the "mask" keyword in a
    > BGP network statement? Ie.
    >
    > Router bgp 65010
    > Network 1.1.1.1
    >
    > VS.
    >
    > Router bgp 65010
    > Network 1.1.1.1 mask 255.255.255.0
    >
    > Thanks,
     
    Gararda, Jun 2, 2006
    #4
  5. Guest

    Your reply was very informative but it is still unclear what the
    difference is between using the bgp Mask keyword and NOT using the mask
    keyword in bgp. could you clarify this specifically.

    Thanks

    Gararda wrote:
    > Hy,
    >
    >
    > If you are using the "no auto-summary" keyword:
    >
    > -You must have a exact match in the IP routing table to appear the
    > network in the BGP routing table. For example:
    > - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
    > appear in the IP routing table.
    > - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
    > appear in the IP routing table.
    >
    >
    > If you are using the "auto-summary" keyword:
    >
    > -You must have the classfull network or a subnet of this classfull
    > network in the IP routing table to appear the network in the BGP
    > routing table. For example:
    > - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
    > or 1.1.1.1/10.... exist in the IP routing table.
    > - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
    > or 1.1.1.1/26.... exist in the IP routing table.
    >
    > CIAO
    >
    > wrote:
    > > Can someone explain the reason for NOT using the "mask" keyword in a
    > > BGP network statement? Ie.
    > >
    > > Router bgp 65010
    > > Network 1.1.1.1
    > >
    > > VS.
    > >
    > > Router bgp 65010
    > > Network 1.1.1.1 mask 255.255.255.0
    > >
    > > Thanks,
     
    , Jun 3, 2006
    #5
  6. Gararda Guest

    Hy,

    If you NOT use the mask keyword in the network stament, BGP use by
    default the classfull network. For example:
    - network 10.1.1.0, the network that BGP install will be
    10.0.0.0/8, because the natural
    mask of this network is a class A. (remember, you must consider
    IP routing table,
    auto-summary.....)

    I hope this help you.

    CIAO.

    wrote:
    > Your reply was very informative but it is still unclear what the
    > difference is between using the bgp Mask keyword and NOT using the mask
    > keyword in bgp. could you clarify this specifically.
    >
    > Thanks
    >
    > Gararda wrote:
    > > Hy,
    > >
    > >
    > > If you are using the "no auto-summary" keyword:
    > >
    > > -You must have a exact match in the IP routing table to appear the
    > > network in the BGP routing table. For example:
    > > - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
    > > appear in the IP routing table.
    > > - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
    > > appear in the IP routing table.
    > >
    > >
    > > If you are using the "auto-summary" keyword:
    > >
    > > -You must have the classfull network or a subnet of this classfull
    > > network in the IP routing table to appear the network in the BGP
    > > routing table. For example:
    > > - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
    > > or 1.1.1.1/10.... exist in the IP routing table.
    > > - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
    > > or 1.1.1.1/26.... exist in the IP routing table.
    > >
    > > CIAO
    > >
    > > wrote:
    > > > Can someone explain the reason for NOT using the "mask" keyword in a
    > > > BGP network statement? Ie.
    > > >
    > > > Router bgp 65010
    > > > Network 1.1.1.1
    > > >
    > > > VS.
    > > >
    > > > Router bgp 65010
    > > > Network 1.1.1.1 mask 255.255.255.0
    > > >
    > > > Thanks,
     
    Gararda, Jun 3, 2006
    #6
  7. maxfactor

    Joined:
    Aug 25, 2006
    Messages:
    1
    Hi, I read somewhere that auto-summary doesn't matter anything with network command. I tried myself to configure a router, and I can say that if I write

    router bgp 1
    network 10.0.0.0
    auto-summary


    ip route 10.10.0.0 255.255.0.0 null0

    then

    show ip bgp

    shows no entries. Cisco student-guide says instead that with the auto-summary , any subnet of the major network specified would prompt the major to be installed in the bgp routing table. But it seems to be not the truth.

    Thanks
     
    maxfactor, Aug 25, 2006
    #7
  8. theapplebee

    Joined:
    Jun 19, 2009
    Messages:
    67
    Location:
    USA
    BGP network mask is used for specify network / CIDR
     
    theapplebee, Sep 8, 2009
    #8
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