Ft Vlan; Configuration Synchronization - Cisco 4700M Administration Manual

Information About Redundancy
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To ensure that bridge learning occurs quickly upon a switchover in a Layer 2 configuration in the case
where a VMAC moves to a new location, the new active member sends a gratuitous ARP on every
interface associated with the active context. Also, when there are two VLANs on the same subnet and
servers need to send packets to clients directly, the servers must know the location of the gateway on the
client-side VLAN. The active member acts as the bridge for the two VLANs. In order to initiate learning
of the new location of the gateway, the new active member sends an ARP request to the gateway on the
client VLAN and bridges the ARP response onto the server VLAN.
During failover, the ACE sends failover traffic to destination addresses as Layer 3 unicast and Layer 2
Note
broadcast. As a result, you may encounter high CPU utilization in the interrupt context on the switch that
connects the two ACEs in the failover setup.

FT VLAN

Redundancy uses a d edicated FT VLAN between redundant ACEs to transmit flow-state information and
the redundancy heartbeat. You configure this same VLAN on both peer appliances.
The two redundant appliances constantly communicate over the FT VLAN to determine the operating
status of each appliance. The standby member uses the heartbeat packet to monitor the health of the
active member. The active member uses the heartbeat packet to monitor the health of the standby
member. Communications over the switchover link include the following data:
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For multiple contexts, the FT VLAN resides in the system configuration file. Each FT VLAN on the ACE
has one unique MAC address associated with it. The ACE uses these device MAC addresses as the source
or destination MACs for sending or receiving redundancy protocol state and configuration replication
packets.

Configuration Synchronization

The ACE automatically replicates the active configuration on the standby member using a process called
configuration synchronization (config sync). Config sync automatically replicates any changes made to
the configuration of the active member to the standby member. After the ACE synchronizes the
redundancy configuration from the active member to the standby peer, it disables configuration mode on
the standby.
For information about configuring config sync, see the
section.
Cisco 4700 Series Application Control Engine Appliance Administration Guide
6-4
HTTP connection states (Optional)
Sticky table
Redundancy protocol packets
State information replication data
Configuration synchronization information
Heartbeat packets
Chapter 6 Configuring Redundant ACEs
"Synchronizing Redundant Configurations"
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