Managing Serviceguard Fifteenth Edition, reprinted May 2008

Understanding Serviceguard Software Components
How the Network Manager Works
Chapter 3108
change. Currently, the ARP messages are sent at the time the IP address
is added to the new system. An ARP message is sent in the form of an
ARP request. The sender and receiver protocol address fields of the ARP
request message are both set to the same floating IP address. This
ensures that nodes receiving the message will not send replies.
Unlike IPv4, IPv6 addresses use NDP messages to determine the
link-layer addresses of its neighbors.
Automatic Port Aggregation
Serviceguard supports the use of automatic port aggregation through
HP-APA (Auto-Port Aggregation, HP product J4240AA). HP-APA is a
networking technology that aggregates multiple physical Fast Ethernet
or multiple physical Gigabit Ethernet ports into a logical link aggregate.
HP-APA allows a flexible, scalable bandwidth based on multiple 100
Mbps Fast Ethernet links or multiple 1 Gbps Ethernet links (or 200
Mbps and 2 Gbps full duplex respectively). Its other benefits include load
balancing between physical links, automatic fault detection, and
recovery for environments which require high availability. Port
aggregation capability is sometimes referred to as link aggregation or
trunking. APA is also supported on dual-stack kernel.
Once enabled, each link aggregate can be viewed as a single logical link
of multiple physical ports with only one IP and MAC address. HP-APA
can aggregate up to four physical ports into one link aggregate; the
number of link aggregates allowed per system is 50. Empty link
aggregates will have zero MAC addresses.
You can aggregate the ports within a multi-ported networking card
(cards with up to four ports are currently available). Alternatively, you
can aggregate ports from different cards. Figure 3-19 shows two
examples.