Why Don’t We Explicitly Bind VIP and SCAN into NIC

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It’s because Oracle clusterware will bind them automatically and dynamically. I think we should try to figure out the interface configurations.

First, let’s see what interfaces we have now.
[root@primary01 ~]$ ll /etc/sysconfig/network-scripts/ifcfg-*
-rw-r--r--  1 root root 314 May 30  2016 /etc/sysconfig/network-scripts/ifcfg-eth0
-rw-r--r--  1 root root 311 May 30  2016 /etc/sysconfig/network-scripts/ifcfg-eth1
-rw-r--r--. 1 root root 254 Jul 22  2014 /etc/sysconfig/network-scripts/ifcfg-lo

But if you list all configuration at run-time, you may see some ghost interfaces. In this case, we can see eth0:1, eth0:4, eth0:5, and eth1:1 are all dynamically registered.
[root@primary01 ~]$ ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:0C:29:6B:9F:79
          inet addr:10.34.98.11  Bcast:10.34.98.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe6b:9f79/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:281243 errors:0 dropped:0 overruns:0 frame:0
          TX packets:98034 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:329861787 (314.5 MiB)  TX bytes:44396484 (42.3 MiB)

eth0:1    Link encap:Ethernet  HWaddr 00:0C:29:6B:9F:79
          inet addr:10.34.98.111  Bcast:10.34.98.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

eth0:4    Link encap:Ethernet  HWaddr 00:0C:29:6B:9F:79
          inet addr:10.34.98.82  Bcast:10.34.98.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

eth0:5    Link encap:Ethernet  HWaddr 00:0C:29:6B:9F:79
          inet addr:10.34.98.81  Bcast:10.34.98.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
eth1      Link encap:Ethernet  HWaddr 00:0C:29:6B:9F:83
          inet addr:10.34.108.11  Bcast:10.34.108.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe6b:9f83/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:87719 errors:2 dropped:2 overruns:0 frame:0
          TX packets:103924 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:58723897 (56.0 MiB)  TX bytes:82332932 (78.5 MiB)
          Interrupt:16 Base address:0x2000

eth1:1    Link encap:Ethernet  HWaddr 00:0C:29:6B:9F:83
          inet addr:169.254.135.24  Bcast:169.254.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:16 Base address:0x2000
...

In the above configurations:
  • eth0 is the Public IP, this is a static interface.
  • eth0:0 is the Virtual IP (VIP) of this node.
  • eth0:4 is the second SCAN IP address.
  • eth0:5 is the third SCAN IP address.
  • eth1 is the Private IP, this is a static interface.
  • eth1:1 is the HAIP address.
That is to say, the first SCAN IP is located at another node.

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