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JUNOSe 11.0.x Physical Layer Configuration Guide
You configure a working interface on the primary port and a corresponding protect
interface on the redundant port of the I/O module. The working interface provides
the primary connection, and the protect interface provides the redundant connection.
The router sends and receives data through both interfaces; however, in normal
operation, only the signal on the working interface is used. If the signal on the primary
interface fails, the router can use the signal on the protect interface. The process by
which the router switches to the protect interface is called switchover.
When you configure APS/MSP, you must assign a working interface and a
corresponding protect interface to a unique group. This group establishes the
relationship between the interfaces. Within the group, each interface is identified by
an APS/MSP channel number. For information about identifying the channel number,
see "Numbering Scheme" on page 81.
You must pair a working interface and its corresponding protect interface on an I/O
module to form a valid linear APS 1+1 group. For example, on an I/O module that
provides four working (primary) ports and four protect (redundant) ports, the working
interface ports are numbered 0–3, and the protect interface ports are numbered
4–7. Table 6 on page 74 lists the pairings required to form four valid APS 1+1 groups
on this I/O module. Each working/protect port pair (for example, port 0 and port 4)
forms a valid APS 1+1 group.
Table 6: Sample Pairings for Valid APS/MSP Groups
Automatic Switchover
Provided you have not issued the aps lockout command for the protect interface,
the router switches over to the protect interface if it detects signal failure. You can
set the SONET/SDH alarms that determine signal failure and signal degradation.
Manual Switchover
When the router is running and you have configured the I/O module for APS/MSP,
you can cause switchover by issuing the aps force or aps manual command.
Switching Mechanisms
E Series Broadband Services Routers support both bidirectional and unidirectional
APS switching modes. By default, the router uses bidirectional switching mode.
74
Overview
Pair This Working Port
With This Protect Port
0
4
1
5
2
6
3
7
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