Agilent Technologies OmniBER 718 SDH User Manual page 102

Selecting Test Features
Generating Automatic Protection Switch (APS) Messages
ACTIVE APS
The ACTIVE APS message type gives real-time response to provide switching
Message Type
keep-alive capability. The instrument will not initiate any changes, but will respond
to change requests that appear on the input K1/K2 byte values.
The ACTIVE APS message type offers two modes:-
• UNIDIRECTIONAL
• BIDIRECTIONAL
The behaviour for each mode is as shown in the following table.
APS MODE
UNIDIRECTIONAL
BIDIRECTIONAL
BIDIRECTIONAL
*
ITU bit numbering convention
where:
xxxx = any 4-bit binary value.
user = user programmable bit, corresponding to APS ARCHITECTURE.
yyyy = any non-zero 4-bit binary value.
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Insert sdh_aps2.bmp
RX K1 TX K1 TX K1
* *
(b5-b8) (b1-b4) (b5-b8)
xxxx 0000 0000
0000 0000 0000
yyyy 0010 yyyy
TX K2 TX K2 TX K2
* * *
(b1-b4) (b5) (b6-b8)
xxxx user 100
0000 user 101
yyyy user 101
101
*