Question re IP address mapping in a RAC environment

From: William Wagman <wjwagman_at_ucdavis.edu>
Date: Thu, 21 Feb 2008 14:38:41 -0800
Message-ID: <FE043305B38A0F448F3924429D650C2A066DAFD6@VEXBE2.ex.ad3.ucdavis.edu>


Greetings,

Below is the output from ifconfig -a on one node of a two node RAC cluster running Oracle 10.2.0.3.0 EE on RHEL4. I just noticed something interesting today. If node 2 of the cluster is down there will appear an entry for eth0:2 with IP address for that node, see below. This makes sense to me, sort of, in that connections from node 2 must be redirected to node 2 and when node 2 comes back up the entry for eth0:2 no longer appears. My question, where can I find an explanation/documentation of what is occurring here and how it functions? I guess this is what the CRS is supposed to be doing, I'm just looking for more detail.

Thanks.

Both nodes up ----------

eth0      Link encap:Ethernet  HWaddr 00:11:43:EB:C7:8C  
          inet addr:128.120.45.32  Bcast:128.120.45.127
Mask:255.255.255.128
          inet6 addr: fe80::211:43ff:feeb:c78c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1157 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5437 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:122271 (119.4 KiB)  TX bytes:619958 (605.4 KiB)
          Interrupt:233 

eth0:1    Link encap:Ethernet  HWaddr 00:11:43:EB:C7:8C  
          inet addr:128.120.45.33  Bcast:128.120.45.127
Mask:255.255.255.128
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:233 

eth1      Link encap:Ethernet  HWaddr 00:11:43:EB:C7:8D  
          inet addr:192.168.10.156  Bcast:192.168.10.255
Mask:255.255.255.0
          inet6 addr: fe80::211:43ff:feeb:c78d/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:65825 errors:0 dropped:0 overruns:0 frame:0
          TX packets:23028 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:70736721 (67.4 MiB)  TX bytes:10977844 (10.4 MiB)
          Interrupt:50 

Added when node 2 unavailable ---------

eth0:2 Link encap:Ethernet HWaddr 00:0F:1F:69:6B:A1

          inet addr:128.120.45.31 Bcast:128.120.45.127 Mask:255.255.255.128

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:233 

Bill Wagman
Univ. of California at Davis
IET Campus Data Center
wjwagman_at_ucdavis.edu
(530) 754-6208

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Received on Thu Feb 21 2008 - 16:38:41 CST

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