HELLO
 
 - Broadcast* HELLO on network segment
 - Receive ACK
 - Establishes 2-way communication
 - Repeat periodically
- Default: HELLO sent every 10 seconds
 - Default: if no HELLO heard for 40 seconds, link is assumed to be dead
 
 - Now establish adjacencies
 
* Actually uses Multicast addresses (224.0.0.9, 224.0.0.10) so that non-OSPF devices can ignore the packets 
 Notes: 
 No notes for slide 17