Handbook

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The switch high availability configurations are based on VRRP. The switch implementation of VRRP
supports the Active-Active mode of high availability.
Active-Active redundancy
In an active-active configuration, shown in the following figure, two switches provide redundancy for
each other, with both active at the same time. Each switch processes traffic on a different subnet. When
a failure occurs, the remaining switch can process traffic on all subnets.
The following figure shows an Active-Active configuration example.
Figure 25 Active-Active redundancy
Extensions to VRRP
This section describes VRRP enhancements that are implemented in this switch:
Tracking VRRP router priority
The switch supports a tracking function that dynamically modifies the priority of a VRRP router, based on
its current state. The objective of tracking is to have, whenever possible, the master bidding processes for
various virtual routers in a LAN converge on the same switch. Tracking ensures that the selected switch is
the one that offers optimal network performance. For tracking to have any effect on virtual router
operation, preemption must be enabled.
The switch can track the attributes listed in the following table:
Table 23 VRRP tracking parameters
Parameter
Description
Number of IP interfaces on the switch that
are active (―up‖)
/cfg/l3/vrrp/track/ifs
Helps elect the virtual routers with the most available
routes as the master. (An IP interface is considered active
when there is at least one active port on the same VLAN.)
This parameter influences the VRRP router's priority in virtual
interface routers.
Number of active ports on the same VLAN
/cfg/l3/vrrp/track/ports
Helps elect the virtual routers with the most available ports
as the master. This parameter influences the VRRP router's
priority in virtual interface routers.
Number of virtual routers in master mode on the switch
/cfg/l3/vrrp/track/vrs
Useful for ensuring that traffic for any particular client/
server pair is handled by the same switch, increasing rout-
ing efficiency. This parameter influences the VRRP router's
priority in virtual interface routers.
Each tracked parameter has a user-configurable weight associated with it. As the count associated with
each tracked item increases (or decreases), so does the VRRP router's priority, subject to the weighting
associated with each tracked item. If the priority level of a standby is greater than that of the current
master, then the standby can assume the role of the master.
See ―Configuring the Switch for Tracking‖ for an example on how to configure the switch for tracking
VRRP priority.