Veritas Storage Foundation 5.0 for Oracle RAC Configuration Guide Extracts for HP Serviceguard Storage Management Suite, Second Edition, May 2008

Introducing Serviceguard Extension for RAC
Low-level Communication: Port Relationship Between GAB and Processes
Chapter 1
18
Low-level Communication: Port Relationship Between
GAB and Processes
All components in SGeRAC use GAB for communication. Each process wanting to
communicate with a peer process on other nodes registers with GAB on a specific port.
This registration enables communication and notification of membership changes. For
example, the SGeRAC engine (had) registers on port h. had receives messages from peer
had processes on port h. had also receives notification when a node fails or when a peer
process on port h becomes unregistered.
Some processes use multiple ports for specific communications requirements. For
example, CVM uses multiple ports to allow communications by kernel and user-level
functions in CVM independently.