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Forum Replies

  1. Hi Rene,

    Really enjoying the OSPF lessons! Just one query, the first output is what you had in the lesson and am just wondering why you chose the network statement for the loopback 0 as area 0, instead of area 0, as in the second output?

    R1#show running-config | section ospf
    router ospf 1
     <strong>network area 0</strong>
     network area 0
    R1#show running-config | section ospf
    router ospf 1
     network area 0
     network area 0
     network 0.0.0.
    ... Continue reading in our forum

  2. Hi Shannon,

    It doesn’t matter much which of the two you pick, both will work. The network command basically checks the IP addresses that you have on your interfaces and if it falls within the range of your network command, it will activate OSPF on it.

    If you use as the network command then any interfaces that have IP address 1.1.1.X on it will run OSPF. If I have a loopback with IP address then this will do the job. The problem is that a loopback with will also be automatically advertised in OSPF since it matches the netw

    ... Continue reading in our forum

  3. Hello Rene,
    One quick question. I am trying to use distribute-list in OSPF in outbound direction, but the command is being rejected and the below error message is showing up. Would you please describe why? Thank you so much.

    R1(config-router)#distribute-list prefix cisco out gigabitEthernet 1/0
    **% Interface not allowed with OUT in case of OSPF**

    Best Regards,

  4. Hello Rene,
    Thanks for your reply. However, I still have a confusion. How does distribute-list work? does it filter LSAs or it resists routes from being installed in the routing table? Let’s say we are looking at topology like below and they are running OSPF:

    Router A------------Router B-(inbound distribute-list)---------------Router C

    Let’s say, Router C has a loopback and it is advertised in OSPF. So if I apply an inbound distribute-list to block on Router B, it does not install route in its routing table. However, it passes the 1.1.1.

    ... Continue reading in our forum

  5. Hello Azm

    Yes, you are correct. The filtering that takes place is filtering of routes from entering the routing table. The filtering does not occur at the interface, but at the mechanism of adding routes to the routing table. Rene mentions the following in the lesson:

    Since the LSDB within the area has to be the same we can’t filter LSAs within the area, we can however filter routes from entering the routing table. Filtering LSAs between areas on an ABR or ASBR is no problem.

    So it is a matter of the definition of the word filter. Filtering in this case

    ... Continue reading in our forum

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