HP ProCurve 9304M Installation And Configuration Manual page 316

Installation and Basic Configuration Guide
and returns to normal Backup status.
• If the Backup does not receive a Hello message with a higher priority than its own by the time the hold-down
timer expires, the Backup becomes the new Master and starts forwarding Layer 2 traffic on all ports.
If you increase the timer scale value, each timer's value is divided by the scale value. To achieve sub-second
failover times, you can change the scale to a value up to 10. This shortens all the VSRP timers to 10 percent of
their configured values.
VSRP Priority Calculation
Each VSRP device has a VSRP priority for each VRID and its VLAN. The VRID is used during Master election for
the VRID. By default, a device's VSRP priority is the value configured on the device (which is 100 by default).
However, to ensure that a Backup with a high number of up ports for a given VRID is elected, the device reduces
the priority if a port in the VRID's VLAN goes down. For example, if two Backups each have a configured priority
of 100, and have three ports in VRID 1 in VLAN 10, each Backup begins with an equal priority, 100. This is shown
in Figure 10.8
Figure 10.8 VSRP priority
Configured priority = 100
Actual priority = 100 * (3/3) = 100
F
VSRP
Aware
However, if one of the VRID's ports goes down on one of the Backups, that Backup's priority is reduced. If the
Master's priority is reduced enough to make the priority lower than a Backup's priority, the VRID fails over to the
Backup. Figure 10.9 shows an example.
10 - 20
VSRP
Master
optional link
F F
Configured priority = 100
Actual priority = 100 * (3/3) = 100
VSRP
Backup
B
VSRP
Aware
B B
VSRP
Aware