Each neighbor can individually issue Hello REQUEST objects. Each request may be answered by an Hello ACK object. The Hello extension is designed so that one side can use the mechanism while the other side does not. All messages may be ignored by nodes which do not wish to participate in Hello message processing. If a particular peer never responds to Hello messages, Extreme routers do not assume that the peer is dead, but simply assume that it does not support Hello messages.
The Hello message has a Msg Type of 20 with a message format as follows:
Hello Message : := Common Header [ INTEGRITY ] Hello