Configuring Tracking And Failure Detection; Overview Of Tracking And Failure Detection - Cisco ACE-4710-K9 Administration Manual

Configuring Tracking and Failure Detection

Configuring Tracking and Failure Detection

Overview of Tracking and Failure Detection

Cisco 4700 Series Application Control Engine Appliance Administration Guide
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This section describes the tracking and failure detection feature of the ACE. This
feature allows you to designate certain network items as critical so that, if one or
more items fail, the ACE reduces the priority of the associated active FT group
accordingly. If the priority of the active FT group falls below the priority of the
corresponding FT group on the standby, a switchover occurs.
This section contains the following topics:
Overview of Tracking and Failure Detection
•
• Configuring Tracking and Failure Detection for a Host or Gateway
Configuring Tracking and Failure Detection for an Interface
•
The ACE supports the tracking and failure detection of several network items. You
can configure an ACE to track and detect failures in the following items in the
Admin context and any user context:
Gateways or hosts
•
• Interfaces
If one of the items that you configure for tracking and failure detection becomes
unresponsive and is associated with the active member of an FT group, by default,
the ACE subtracts a value of 0 from the configured priority of the active member.
If you configure a nonzero value for the tracking priority and the resulting priority
value of the active member is less than that of the standby member, the active
member switches over and the standby member becomes the new active member.
All active flows that exist at the time of the switchover continue uninterrupted on
the new active member of the FT group.
When the failed item comes back up, the ACE increments the priority of the
associated group member by a value of 0 by default. If you configure a non-zero
value for the tracking priority and the resulting priority of the standby member is
greater than the priority of the active member, a switchover occurs back to the
original active group member.
You can configure the unit priority associated with tracked items to be greater than
0. This option allows you to fine tune the switchover scenario so that a switchover
occurs when either all or any of the tracked objects fails.
Chapter 7 Configuring Redundant ACE Appliances
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