CTI Products EXB Network Manager - Manual (Page 10)

Hot-Standby EXB / Network Manager Software Manual Hot Standby
CTI Products, Inc. EXB Operation
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68-11707-100
2.3 Normal Link Condition
Figure 2 Normal Link Operation
In Normal Operation:
1. The Main EXB Control Neuron issues a Probe packet to the Standby EXB
Control Neuron
2. The Standby Control Neuron returns a Probe ACK.
3. When the Main EXB Control Neuron receives the Probe ACK, it issues a Holdoff
packet to the Standby EXB Control Neuron.
3a The Standby EXB Control Neuron will return a Holdoff ACK (not shown)
4. Since the Standby EXB Control Neuron received both a Probe and a Holdoff
packet, it keeps its switch open and does not pass normal MCN traffic to or from
the remote site.
Central EXBs Remote EXBs
Hot Standby -- Normal Loop CA-80599-100
WAN Links
Router
Control Neuron
Port 1
B A
Switch
In
Out
Router
Control Neuron
Port 1
B A
4. Switch remains Open
In
Out
Router
Control Neuron
Port 1
B A In
Out
Router
Control Neuron
Port 1
B A In
Out
Main
Standby
1. Probe Packet
2. Probe Ack
2. Probe Ack
1. Probe Packet
3. Holdoff Packet
A
B D
C
3. Holdoff Packet