RAC network interconnect

RAC network interconnect

What are different RAC network components ?

Public IP address is the normal IP address typically used by DBA and SA to manage storage, system and database. Public IP addresses are reserved for the Internet.
Private IP address is used only for internal clustering processing (Cache Fusion) (aka as interconnect). Private IP addresses are reserved for private networks.
VIP is used by database applications to enable fail over when one cluster node fails. The purpose for having VIP is so client connection can be failover to surviving nodes in case there is failure

 

How to find IP’s information in RAC ?

Edit the /etc/hosts file as shown below:
# Do not remove the following line, or various programs
# that requires network functionality will fail.
127.0.0.1               localhost.localdomain localhost
## Public Node names
 192.168.10.11          node1-pub.hingu.net     node1-pub
192.168.10.22          node2-pub.hingu.net     node2-pub
## Private Network (Interconnect)
 192.168.0.11            node1-prv               node1-prv
192.168.0.22            node2-prv               node2-prv
## Private Network (Network Area storage)
 192.168.1.11            node1-nas               node1-nas
192.168.1.22            node2-nas               node2-nas
192.168.1.33            nas-server              nas-server
## Virtual IPs
 192.168.10.111          node1-vip.hingu.net     node1-vip
192.168.10.222          node2-vip.hingu.net     node2-vip

In 2 node RAC, how many NIC’s are r using ?

2 network cards on each clusterware node
Network Card 1 (with IP address set 1) for public network
Network Card 2 (with IP address set 2) for private network (for inter node communication between rac nodes used by clusterware and rac database)

In 2 node RAC, how many IP’s are r using ?

6 - 3 set of IP address
## eth1-Public:  2
## eth0-Private: 2
## VIP: 2

How can we configure the cluster interconnect?

· Configure User Datagram Protocol (UDP) on Gigabit Ethernet for cluster interconnects.
· On UNIX and Linux systems we use UDP and RDS (Reliable data socket) protocols to be used by Oracle Clusterware.
· Windows clusters use the TCP protocol.

What is the purpose of Private Interconnect?

Clusterware uses the private interconnect for cluster synchronization (network heartbeat) and daemon communication between the the clustered nodes. This communication is based on the TCP protocol.
RAC uses the interconnect for cache fusion (UDP) and inter-process communication (TCP). Cache Fusion is the remote memory mapping of Oracle buffers, shared between the caches of participating nodes in the cluster.

Why do we have a Virtual IP (VIP) in Oracle RAC?

Without using VIPs or FAN, clients connected to a node that died will often wait for a TCP timeout period (which can be up to 10 min) before getting an error. As a result, you don't really have a good HA solution without using VIPs.

When a node fails, the VIP associated with it is automatically failed over to some other node and new node re-arps the world indicating a new MAC address for the IP. Subsequent packets sent to the VIP go to the new node, which will send error RST packets back to the clients. This results in the clients getting errors immediately.

Give situations under which VIP address failover happens?

VIP addresses failover happens when the node on which the VIP address runs fails; all interfaces for the VIP address fails, all interfaces for the VIP address are disconnected from the network.

What is the significance of VIP address failover?

When a VIP address failover happens, Clients that attempt to connect to the VIP address receive a rapid connection refused error .They don't have to wait for TCP connection timeout messages.

 

Can application developer access the private ip ?
No. private IP address is used only for internal clustering processing (Cache Fusion) (aka as interconnect)