Configuring the WSM using Device Manager

ARP health checking  

Address Resolution Protocol (ARP) is the TCP/IP protocol that resides within the Internet layer. ARP resolves a physical address from an IP address. ARP queries machines on the local network for their physical addresses. ARP also maintains IP to physical address pairs in its cache memory. In any IP communication, the ARP cache is consulted for the presence of the IP address of the computer or the router. If present, ARP resolves the physical address to send a packet. In the WSM, this feature allows the user to health check the Intrusion Detection Server (IDS) by sending an ARP query. The ARP health check consists of:

1. Accessing the ARP table.
2. Looking for the session entry in the ARP table. If the entry exists in the table, that means the real server is up, otherwise the health check has failed.
3. If present, checking the timestamp to find out if the last used time is greater than the ARP health check interval. If it is, then delete the query, as this means that the health check has failed.
4. Sending another ARP request and repeating the above process until the timestamp shows the last used time smaller than the ARP health check interval.

To configure ARP health checks, choose ARP from the health check selection list for the real server group. See Configuring a health check for a real server group.

See also:

• ICMP health checking
• Direct server return health checking
• Link health checking
• TCP health checking
• Script-based health checking
• Modifying the health check interval and retries
• Application health checking
• About health checking