VIP in RAC
What’s SCAN IP used for?
Receive connection from client and pass on to local listeners
- Each SCAN VIP has SCAN Listener associated with each other and both works as a pair. One SCAN Listener is created corresponding to one SCAN VIP.
- Whenever a new connection request is made the SCAN listener listening on a SCAN IP address and the SCAN port is contracted on a client’s behalf. Because all services on the cluster (HS: even the nodes that have no scan listener running on) are registered with the SCAN listener, the SCAN listener replies with the address of the local listener as Node VIP address on the least-loaded node (Each scan listener keeps updated cluster load statistics) and connection is routed to that node.
What’s VIP used for ?
The local listener run on the VIP. If local node failed, the VIP is moved to surviving node, avoiding the long delay of TCP time out.
srvctl status vip -n rad1dev
srvctl config scan
srvctl config scan_listener
Very good article:
- Virtual IP must be associated with the same interface name on every node that is a part of the cluster
- The Virtual IP address should not be in use at the time of the installation because this is a Virtual IP address that Oracle manages internally to the RAC processes.
- This virtual IP address does not require a separate NIC. The VIPs should be registered in the DNS.
- Virtual IP (VIP) is for fast connection establishment in failover dictation