HP StorageWorks Scalable File Share System Installation and Upgrade Guide Version 2.2

Planning the networks 2–15
Figure 2-8 shows an example of a dual-link server to dual-link client node network where the networks are
not physically separate.
Figure 2-8 Dual-link server to dual-link client node configuration — networks not physically separate
In this setup, the netmasks on each interface should prevent a message being sent from the wrong interface,
because the kernel routing table chooses the only interface that can communicate with the IP address the
message is destined for (this is the reason for configuring the two networks to be logically separate). To send
a message, the kernel first determines the MAC address of the interface where the message is to be sent,
by broadcasting an ARP request from all local interfaces across the network. Both client links receive the
ARP request and both interfaces respond to it, each sending its own MAC address. The system that issued
the ARP request uses the first response that it receives as the destination for the IP address. As a result, there
is a possibility that messages for both networks will be sent to a single interface on the client. Setting the
arp_ignore parameter on the client nodes to 1 prevents this from happening.