Basic lab config - where is my default route wrong

Discussion in 'Cisco' started by evergladesfl, Sep 4, 2006.

  1. evergladesfl

    evergladesfl Guest

    I have two 2501s that I am playing with for CCNA lab exercises.
    BHM is the router connected to the Internet gateway (the gateway's
    internal address is 192.168.0.3).
    The problem I am experiencing is that I cannot get to the Internet from
    GAD (see configs below), though I can from BHM:

    =========================
    sho run
    BHM#sho running-config
    !
    version 12.2
    !
    ip subnet-zero
    no ip domain-lookup
    !
    interface Ethernet0
    ip address 192.168.0.80 255.255.255.0
    !
    interface Serial0
    ip address 172.17.0.2 255.255.0.0
    clockrate 56000
    !
    router rip
    version 2
    network 172.17.0.0
    network 192.168.0.0
    !
    ip classless
    ip route 0.0.0.0 0.0.0.0 192.168.0.3
    ==============================
    sho run
    GAD#sho running-config

    version 12.2
    !
    ip subnet-zero
    no ip domain-lookup
    !
    interface Ethernet0
    ip address 172.16.0.1 255.255.0.0
    !
    interface Serial0
    ip address 172.17.0.1 255.255.0.0
    !
    router rip
    version 2
    network 172.16.0.0
    network 172.17.0.0
    !
    ip classless
    ip default-network 192.168.0.0

    ===========================
    as the Internet gateway. But I can get no further than that interface
    (cannot ping 192.168.0.3). From BHM I can ping anywhere on the
    Internet.

    Please help me make sense of this.

    Thanks

    -tom
     
    evergladesfl, Sep 4, 2006
    #1
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  2. evergladesfl

    erik.freitag Guest

    "If the router has a directly connected interface onto the specified
    network, the dynamic routing protocols running on that router will
    generate (or source) a default route. For Router Information Protocol
    (RIP), this is flagged as the pseudonetwork 0.0.0.0; for Interior
    Gateway Routing Protocol (IGRP), it is the network itself, flagged as
    an exterior route."

    If this is the entire configuration, then your router GAD has no need
    to source a default route (which would be sent to other routers). Even
    if it does need to generate a default route via rip, it has no directly
    connected interface to the 192.168.0.0 network as required.

    For your purposes I think a simple "ip route 0.0.0.0 0.0.0.0
    172.17.0.2" would work best.

    I would also change the mask on your serial interfaces to
    255.255.255.252, but that's just me. They should work OK as specified.
     
    erik.freitag, Sep 4, 2006
    #2
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  3. evergladesfl

    evergladesfl Guest

    Thanks for the reply. I have not yet used the the ip route 0.0.0.0
    0.0.0.0 172.17.0.2 command you suggest, but will give it a go.

    One thing that I still do not understand is why GAD cannot get to the
    address 192.168.0.3, since it does have a route to 192.168.0.0 and can
    get to 192.168.0.80 (e0 on BHM).

    Could you help me understand this?

    Thanks
     
    evergladesfl, Sep 4, 2006
    #3
  4. evergladesfl

    chris Guest

    So does the internet gateway on 192.168.0.3 have a route back to GAD via the
    BHM router?

    Chris.
     
    chris, Sep 4, 2006
    #4
  5. evergladesfl

    evergladesfl Guest

    Crap - that's it!

    Thanks!
     
    evergladesfl, Sep 4, 2006
    #5
  6. evergladesfl

    ramesh51281 Guest

     
    ramesh51281, Sep 8, 2006
    #6
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