We're Sorry, Full Content Access is for Members Only...

If you like to keep on reading, Become a Member Now! Here is why:

  • Learn any CCNA, CCNP and CCIE R&S Topic. Explained As Simple As Possible.
  • Full Access to our 644 Lessons. More Lessons Added Every Week!
  • Content created by Rene Molenaar (CCIE #41726)

466 Sign Ups in the last 30 days

satisfaction-guaranteed
100% Satisfaction Guaranteed!
You may cancel your monthly membership at any time.
No Questions Asked!

Forum Replies

  1. Hello,

    I have a question regarding passive interfaces. From my understanding a “passive interface” under OSPF doesn’t send hello packets and makes adjacencies. I have the following config up on a router and would like clarification:

    Routing Protocol is "ospf 250"
      Outgoing update filter list for all interfaces is not set
      Incoming update filter list for all interfaces is not set
      Router ID 10.16.1.1
      Number of areas in this router is 1. 1 normal 0 stub 0 nssa
      Maximum path: 4
      Routing for Networks:
        10.0.0.0 0.255.255.255 area 28
      Passive Interface(s)
    ... Continue reading in our forum

  2. Rohitendu,
    Cisco has five different options for OSPF over NBMA. Which one you should choose depends on several factors. One important consideration is whether the circuit supports multicast–this will determine whether you must define neighbors manually, or if they can discover each other. Additionally, you need to consider what is the topology of your WAN connection–full mesh, hub and spoke, …? This is important because you must ensure that any router eligible to be a DR or BDR must have reachability to all the other OSPF nodes.

    Here is some information on

    ... Continue reading in our forum

  3. Hi Rene,

    Please help! My topology is simple. R1–FW–R2. I am running ospf between R1 and R2. Firewall between R1 and R2 is transparent. R1 and R2 are able to ping each other through the firewall. However, I keep getting this error message. The hello and dead timer are identical on both R1 and R2. The neighbor already formed. However, it will disconnect and re-form back and forth…

    *Mar  1 03:11:10.743: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on FastEthernet0/1 from FULL to DOWN, Neighbor Down: Dead timer expired
     --More--
    *Mar  1 03:11:15.243: %OSPF-5-ADJCHG: Proc
    ... Continue reading in our forum

  4. Georgi,
    I think this question would need some clarification, and it depends on whether the two routers are the ONLY routers that are neighbors, or whether there are more than two routers.

    The situation you describe could happen where the router that is in 2-Way has not been elected as a DR or BDR. In this situation (assuming we are dealing with a multi-access network), this is perfectly normal to have a 2-Way state. Any router that is not a DR or BDR that has a neighbor relationship with another router that is also not a DR or BDR would show up as 2-Way/DROTH

    ... Continue reading in our forum

  5. Hi Networklesson team ,

    I was searching for a issue that “why ospf neighbors will stuck at exstart/exchange state” , i got good explanation at below cisco link .

    https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13684-12.html

    please note at step 5 :
    ____________________________________________________________________________________
    Router 7 debug output:

    ***OSPF ENABLED ON ROUTER7, BEGINS SENDING 
    HELLOS AND BUILDING A ROUTER LSA  ////please note router building LSA Type 1////
    00:17:44: IP: s=170.170.11.7 (local), d=224.0.0.5 
    (Seria
    ... Continue reading in our forum

14 more replies! Ask a question or join the discussion by visiting our Community Forum