Hey all,

Released a new OSPF video in my Practical OSPF series:

https://www.youtube.com/watch?v=Mi3tNSUjb78

The Designated Router (DR) and Backup Designated Router (BDR) exist to reduce redundant LSA flooding on an OSPF multi access link.

In this video we explore ...

• the process and packets involved in a DR and BDR are election
• the WAIT interval in OSPF
• Preemption and Priority numbers
• the sequence of events that occurs when a routing update needs to be sent on a link with a DR and BDR
  • including how exactly the multicast addresses 224.0.0.5 and 224.0.0.6 are used

This is a continuation to my Practical OSPF series I first posted about a few months ago.

Timestamps if you only want to check out certain parts:

• 00:00 - Intro
• 00:11 - DR BDR - Review
• 01:26 - Electing Process: DR, BDR, and Drothers
• 06:14 - Neighbor Adjacency Process - Full or 2-WAY
• 08:29 - DR / BDR / Priority are Per-Interface, not Per-Router
• 09:06 - Deterministic Designated Router by setting Priority
• 12:07 - Routing Updates from DR, BDR, and Drothers - 224.0.0.5 - 224.0.0.6
• 15:27 - Packet Capture of OSPF DR BDR Election Process and Routing Updates