Alcatel MainStreet 2902, Manual, Page: 242 / 344

23 — Cross-connecting circuits
23-8 2902 MainStreet Technical Practices
90-2906-01 May 2002
Automatic override
Figure 23-5 shows an example where circuit 1-1 is connected to circuit P1-1 and is
protected by circuit P2-1. Circuit 2-1 is connected to circuit P2-1. When all circuits
are available, the connection between circuits 1-1 and P1-1 is active, as is the
connection between circuits 2-1 and P2-1.
If circuit P1-1 fails or becomes unavailable, circuit 1-1 switches to P2-1 and the
connection between circuits 2-1 and P2-1 is overridden (see Figure 23-6). Circuit 1-1
switches back to its preferred connection when circuit P1-1 becomes available.
Figure 23-5 Preferred connections available
Caution —
A connection that shares a protecting circuit may be
broken without warning at any time, because the protecting circuit
must connect to the circuit it has been configured to protect.
Primary
rate
module
Protecting
circuit
Control
card
Data
module
2-1
Primary
rate
module Data
module
1-1
DX
2902 MainStreet node
Primary
rate link
Primary
rate link
Protecting
connection
Preferred
circuit
Preferred
connection
inactive
Data
device
P2-1
P1-1
8872
Not
protected
Protected
circuit