Juniper Networks E-Series - Manual (Page 40)

CHAPTER 1
E-Series Overview 1-18
The process by which the system switches to the spare line module is
called switchover. When switchover occurs, the system:
1 Breaks the connection between the primary I/O module and the
primary line module.
2
Connects the primary I/O module to the spare line module via the
redundancy midplane and redundancy I/O module.
Protocol processing then takes place on the spare line module.
Figure 1-15 shows the data flow when a spare line module becomes
active.
Figure 1-15 Data flow when a spare line module is active
Midplane

Œ
Redundancy
midplane
Spare line module
Primary line module
Redundancy
I/O module
Primary
I/O module

Ž
1. A packet arrives at the primary I/O module.
2. The packet passes along the redundancy
midplane from the primary I/O module to
the redundancy I/O module.
3. The packet passes from the redundancy
I/O module to the spare line module.
4. The spare line module processes the packet.
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