HP ProCurve NAC 800, User Manual, Page: 308 / 591

High Availability and Load Balancing
Load Balancing
8-6
Load Balancing
Load balancing distributes the testing of endpoints across all NAC 800 ESs in
a cluster. NAC 800 uses a hashing algorithm based on MAC or IP addresses to
divide the endpoints between the ESs.
If the MAC address is unavailable (untestable endpoint) the IP address is used
to determine which ES should test an endpoint. If an ES detects an endpoint
for which it is not responsible, it notifies the correct ES of the endpoint and
that ES takes over testing.
If an ES fails, any services that are protected by that ES may become inacces-
sible, depending on the nature of the ES failure. However, the redundant
services that are
protected by the other ESs are still available.
TIP:
Protected services are services that are running on any servers that sit on the
eth1 side of the failed ES, such as AD, DNS, DHCP, NTP, file server, print
server, and so on.