Cisco Explorer 4700 Installationsanleitung PDF herunterladen (Seite 398)

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Device Manager Guide, Cisco ACE 4700 Series Application Control Engine Appliance

OL-26645-02

Chapter 11 Configuring High Availability

Understanding ACE Redundancy

Redundancy provides seamless switchover of flows in case an ACE appliance becomes unresponsive or

a critical host or interface fails. Redundancy supports the following network applications that require

fault tolerance:

• Mission-critical enterprise applications

• Banking and financial services

• E-commerce

• Long-lived flows such as FTP and HTTP file transfers

The following overview topics describe high availability as performed by the ACE appliance:

• High Availability Polling, page 11-2

• Redundancy Protocol, page 11-3

• Stateful Failover, page 11-4

• Fault-Tolerant VLAN, page 11-5

• Configuration Synchronization, page 11-5

• Synchronizing High Availability Configurations with ACE Appliance Device Manager, page 11-6

• Redundancy Configuration Requirements and Restrictions, page 11-6

Related Topics

• Configuring ACE High Availability, page 11-8

• Configuring High Availability Peers, page 11-8

• Configuring ACE High Availability Groups, page 11-11

High Availability Polling

Approximately every two minutes, the ACE appliance Device Manager issues the show ft group

command to the ACE appliance to gather the redundancy statistics of each virtual context. The state

information is displayed in the HA State and HA Peer State fields when you click Config > Virtual

Context. The possible states are as follows:

• Active—Local member of the FT group is active and processing flows.

• Standby Cold—Indicates if the FT VLAN is down but the peer device is still alive, or the

configuration or application state synchronization failed. When a context is in this state and a

switchover occurs, the transition to the ACTIVE state is stateless.

• Standby Bulk—Local standby context is waiting to receive state information from its active peer

context. The active peer context receives a notification to send a snapshot of the current state

information for all applications to the standby context.

• Standby Hot—Local standby context has all the state information it needs to statefully assume the

active state if a switchover occurs.

• Standby Warm—Allows the configuration and state synchronization process to continue on a

best-effort basis when you upgrade or downgrade the ACE software.

• N/A—Indicates that the ACE Device Manager received an empty state from the ACE which can

occur during a transition period between state changes, for example, during a switchover.

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