Using the same IP subnet on the VERITAS Cluster Server Public network adapter and on both Cluster Server Heartbeat adapters can cause IP routing problems when the adapters are not on the same physical network.

Article:TECH19072  |  Created: 2002-01-18  |  Updated: 2005-01-28  |  Article URL http://www.symantec.com/docs/TECH19072
Article Type
Technical Solution


Environment

Issue



Using the same IP subnet on the VERITAS Cluster Server Public network adapter and on both Cluster Server Heartbeat adapters can cause IP routing problems when the adapters are not on the same physical network.

Solution



Using the same IP subnet on the VERITAS Cluster Server Public network adapter (Figure 1) and on both Cluster Server Heartbeat adapters (Figure 2) can cause IP routing problems when the adapters are not on the same physical network.

Figure 1
 

Figure 2 (For simplicity, only the Heartbeat with the highest host ID is shown.)
 

The problem occurs when a virtual IP address is brought online and it forces the routing engine to recalculate the IP routing table.  When the routing engine has more than one path to a defined default gateway, it selects the path that has the highest host ID for that subnet (Figure 3 and 4).  If the heartbeat card has the highest IP address for that subnet, it is selected as the route to the default gateway though it has no physical path to the default gateway.  See Microsoft Knowledge Base Article "Expected Behavior of Multiple Adapters on Same Network" (Q175767) for details

Figure 3
 

Figure 4 (For simplicity, only the Heartbeat with the highest host ID is shown.)
 

Workaround
Assign a different IP subnet to each of the Heartbeat networks and to the Public network (minimum of three IP subnets are required)  
- Or -
Disable IP from each of the Heartbeat network adaptors*

*VERITAS Cluster Server does not require IP for the Heartbeat network.



Legacy ID



245717


Article URL http://www.symantec.com/docs/TECH19072


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