Managing Serviceguard Eighteenth Edition, September 2010

Jumbo Frames. Additionally, network interface cards running 1000Base-T or 1000Base-SX
cannot do local failover to 10BaseT.
During the transfer, IP packets will be lost, but TCP (Transmission Control Protocol)
will retransmit the packets. In the case of UDP (User Datagram Protocol), the packets
will not be retransmitted automatically by the protocol. However, since UDP is an
unreliable service, UDP applications should be prepared to handle the case of lost
network packets and recover appropriately. Note that a local switchover is supported
only between two LANs of the same type. For example, a local switchover between
Ethernet and IPoIB interfaces is not supported, but a local switchover between 10BT
Ethernet and 100BT Ethernet is supported.
Figure 3-16 shows two nodes connected in one bridged net. LAN segments 1 and 2 are
connected by a hub.
Figure 3-16 Cluster Before Local Network Switching
Node 1 and Node 2 are communicating over LAN segment 2. LAN segment 1 is a
standby.
In Figure 3-17, we see what would happen if the LAN segment 2 network interface
card on Node 1 were to fail.
94 Understanding Serviceguard Software Components