SDP keepalives actively monitor the SDP operational state using periodic Nokia SDP ping echo request and echo reply messages. Nokia SDP ping is a part of Nokia’s suite of service diagnostics built on an Nokia service-level OA&M protocol. When SDP ping is used in the SDP keepalive application, the SDP echo request and echo reply messages are a mechanism for exchanging far-end SDP status.
Configuring SDP keepalives on a specific SDP is optional. SDP keepalives for a particular SDP have the following configurable parameters:
admin up/admin down state
hello time
message length
max drop count
hold down time
SDP keepalive echo request messages are only sent when the SDP is completely configured and administratively up and SDP keepalives is administratively up. If the SDP is administratively down, keepalives for the SDP are disabled.
SDP keepalive echo request messages are sent out periodically based on the configured Hello Time. An optional message length for the echo request can be configured. If max drop count echo request messages do not receive an echo reply, the SDP is immediately brought operationally down.
If a keepalive response is received that indicates an error condition, the SDP is immediately brought operationally down.
When a response is received that indicates the error has cleared and the hold down time interval has expired, the SDP is eligible to be put into the operationally up state. If no other condition prevents the operational change, the SDP enters the operational state.