The animated TECHTip Tutorial is available here.

This is a review of the OSPF [Open Shortest Path First] hello packet processes and the creation of DR [Designated Routers] and BDR [Backup Designated Routers] and going from a loading to full state operation. That is, once you have decided the OSPF area types, then router types, you can use message types to set up the network.

Responding routers reply with Hello LSA [Local Security Authority] packet with following information:

• Router ID - highest active IP address or loopback interface IP address

• Time intervals - Time intervals between hello packets and dead time
• Existing neighbors - IP addresses for existing OSPF neighbors
• Area IDentification - OSPF area number and link information
• Router priority - value used to select DR and BDR
• DR and BDR - name of selected DR and BDR
• Authentication password - all peers share same password
• Stub area flag - neighbors must share same stub information

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Tags: ospf, open shortest path first, lsa, designated routers, backup designated routers, local security authority