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.
  • Try for Just $1. The Best Dollar You've Ever Spent on Your Cisco Career!
  • Full Access to our 622 Lessons. More Lessons Added Every Week!
  • Content created by Rene Molenaar (CCIE #41726)


447 New Members signed up the last 30 days!


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

Tags: ,

Forum Replies

  1. Jason,
    DRs and BDRs are not necessarily one-to-one with Areas. I think this is the key point to answer your question. DRs and BDRs are the result of the OSPF network type defined on a Router’s interface, not because of some requirement of an Area to have them. OSPF recognizes the following network types:

    • Broadcast
    • Non-Broadcast
    • Point to Multipoint (Broadcast)
    • Point to Multipoint (Non-Broadcast)
    • Point to Point

    Out of all of those possibilities, only Broadcast and Non-Broadcast form DRs and BDRs. The Broadcast and Non-Broadcast network types describe a

    ... Continue reading in our forum

  2. Hi,

    I have a question, In the process of election DR/ BDR, who will elect first? DR or BDR ?
    I have only one router in my setup. I configured OSPF on that router and I started debug message. After the end of wait period ( dead interval 40 sec), router considers himself as BDR and then moved to DR .
    please explain me, in the election process, will BDR is elected first or DR ?

    Below is the debug message:

        *Mar  1 00:01:12.207: %SYS-5-CONFIG_I: Configured from console by console
        *Mar  1 00:01:18.215: OSPF: Send hello to area 0 on Fas
    ... Continue reading in our forum

  3. Azeem,
    The BDR is elected first (see step #7 below). Here is a break down of what happens during the election:

    1. Once an OSPF becomes active on a multi-access network, it sets the DR and BDR values to which indicates these are unknown. It also starts a wait timer of the value of the dead interval.
    2. The router starts neighbor discovery. It sends the values for DR/BDR
    3. If a received Hello includes values for DR/BDR, these are accepted and the wait timer is stopped
    4. If the wait timer expires, the DR election starts
    5. A list of neighbors on the multiac
    ... Continue reading in our forum

  4. Hi Rene,

    Thanks for sharing your knowledge. Your teaching gives us a great confidence.

    I have a doubt. Among DR and BDR, who is elected first ?


  5. Thanks Laz! Good to know I understand this correctly. :grinning:

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