I face with that issue on 2 node 11.2.0.2 RAC system on AIX 6.1. I have script which checking my alert.log. I have email about my second node goes down.

Firstly, I checked my database up or not. It was up and also query gave output. Secondly I started to investigate log files. While I was checking my services by crsctl stat res -t command.
——————————————————————————–
NAME TARGET STATE SERVER STATE_DETAILS
——————————————————————————–
Local Resources
——————————————————————————–
ora.node2.vip
1 ONLINE UNKNOWN node2 CHECK TIMED OUT

ora.scan1.vip
1 ONLINE UNKNOWN node2 CHECK TIMED OUT

As you can see for VIP and SCANIP the status is CHECK TIMED OUT.

I used 2 IP for SCANIP configuration.
On node one 1 run ifconfig command on node 1 I could see my VIP,realIP,SCANIP.

On node one 2 run ifconfig command on node 2 I could see not see my VIP and SCANIP.There is just realIP avaliable.

I started to check alert log from $GRID_HOME/logs/node2.

There are some error messages such as:

2012-08-23 15:01:04.446: [ AGFW][1817] {0:2:16438} Command: check for resource: ora.node2.vip 1 1 completed with status: TIMEDOUT
2012-08-23 15:01:04.447: [ AGFW][2314] {0:2:16438} Agent sending last reply for: RESOURCE_CLEAN[ora.node2.vip 1 1] ID 4100:3496733
2012-08-23 15:01:04.448: [ora.node2.vip][1817] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:01:04.571: [ora.scan1.vip][2574] {0:2:16438} [check] got lock
2012-08-23 15:01:04.571: [ora.scan1.vip][2574] {0:2:16438} [check] tryActionLock }
2012-08-23 15:01:04.571: [ora.scan1.vip][2574] {0:2:16438} [check] abort }
2012-08-23 15:01:04.571: [ora.scan1.vip][2574] {0:2:16438} [check] clsn_agent::abort }
2012-08-23 15:01:04.571: [ AGFW][2574] {0:2:16438} Command: check for resource: ora.scan1.vip 1 1 completed with status: TIMEDOUT
2012-08-23 15:01:04.572: [ AGFW][2314] {0:2:16438} Agent sending last reply for: RESOURCE_CLEAN[ora.scan1.vip 1 1] ID 4100:3496737
2012-08-23 15:01:04.573: [ora.scan1.vip][2574] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:01:04.652: [ AGFW][2314] {0:2:16438} Agent received the message: RESOURCE_CLEAN[ora.scan1.vip 1 1] ID 4100:3496808
2012-08-23 15:01:04.652: [ AGFW][2314] {0:2:16438} Preparing CLEAN command for: ora.scan1.vip 1 1
2012-08-23 15:01:04.652: [ AGFW][2314] {0:2:16438} ora.scan1.vip 1 1 state changed from: UNKNOWN to: CLEANING

$GRID_HOME/logs/node2/agent/crsd/orarootagent_root/orarootagent_root.log there are also error messages such as:

2012-08-23 15:53:47.476: [ora.scan1.vip][1497] {0:17:2} [check] clsn_agent::abort }
2012-08-23 15:53:47.476: [ AGFW][1497] {0:17:2} Command: check for resource: ora.scan1.vip 1 1 completed with status: TIMEDOUT
2012-08-23 15:53:47.477: [ora.scan1.vip][1497] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:47.916: [ora.node2.vip][2214] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:48.477: [ora.scan1.vip][1497] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:48.916: [ora.node2.vip][2214] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:49.478: [ora.scan1.vip][1497] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:49.917: [ora.node2.vip][2214] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:50.478: [ora.scan1.vip][1497] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:50.917: [ora.node2.vip][2214] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:51.479: [ora.scan1.vip][1497] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:51.917: [ora.node2.vip][2214] {0:17:2} [check] Waiting for Network Object to be initialized
2012-08-23 15:53:52.330: [ora.registry.acfs][3223] {0:17:2} [check] Filling Environment Map with _ORA_CHECK_TIMEOUT = 600
2012-08-23 15:53:52.331: [ora.registry.acfs][3223] {0:17:2} [check] Filling Environment Map with _ORA_CHECK_TYPE = CLSAGFW_PERIODIC_CHECK
2012-08-23 15:53:52.331: [ora.registry.acfs][3223] {0:17:2} [check] RegistryAcfsAgent:: Calling check

So I solved issue by starting scan1 services:

# crsctl start res ora.scan1.vip
CRS-2672: Attempting to start ‘ora.net1.network’ on ‘node2’
CRS-2676: Start of ‘ora.net1.network’ on ‘node2’ succeeded
CRS-2672: Attempting to start ‘ora.ons’ on ‘node2’
CRS-2672: Attempting to start ‘ora.scan1.vip’ on ‘node2’
CRS-2676: Start of ‘ora.ons’ on ‘node2’ succeeded
CRS-2676: Start of ‘ora.scan1.vip’ on ‘node2’ succeeded
CRS-2672: Attempting to start ‘ora.LISTENER_SCAN1.lsnr’ on ‘node2’
CRS-2676: Start of ‘ora.LISTENER_SCAN1.lsnr’ on ‘node2’ succeeded

After run this command state became normal

——————————————————————————–
NAME TARGET STATE SERVER STATE_DETAILS
——————————————————————————–
Local Resources
——————————————————————————–
ora.node2.vip
1 ONLINE ONLINE node2

ora.scan1.vip
1 ONLINE ONLINE node2

Source:
SCAN VIP Showing Status UNKNOWN – CHECK TIMED OUT On One Node [ID 1341882.1]