当某个实例的监听收到客户端连接请求，将会统筹考虑RAC环境中各个节点的负载情况，然后将该连接传递到具有最小负载的节点的最小负载实例上。
1. Instance_A is locally registered with Listener_A and remotely registered with Listener_B. Instance_B is registered locally with Listener_B and remotely with Listener_A.
2. Client connection #1 goes to Listener_A. Based on load information provided by PMON, Listener_A routes the incoming client to the locally registered instance, Instance_A.
Listener_A.log:
13-FEB-2004 11:05:02 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=prod)
(CID=(PROGRAM=)(HOST=clienthost)(USER=oracle))) *
(ADDRESS=(PROTOCOL=tcp)(HOST=10.10.10.10)(PORT=20108)) * establish * prod * 0
1. client connection #2 goes to Listener_A. With updated load information provided by PMON, Listener_A routes the client to the remotely registered instance, Instance_B.
Listener_A.log:
13-FEB-2004 11:05:02 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=prod)
(CID=(PROGRAM=)(HOST=clienthost)(USER=oracle))) *
(ADDRESS=(PROTOCOL=tcp)(HOST=10.10.10.10)(PORT=20108)) * establish * prod * 0
Listener_B.log:
13-FEB-2004 11:05:02 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=prod)
(CID=(PROGRAM=)(HOST=clienthost)(USER=oracle))(INSTANCE_NAME=Instance_B)) *
(ADDRESS=(PROTOCOL=tcp)(HOST=10.10.10.10)(PORT=20110)) * establish * prod * 0
在10gR2版本之后，节点和实例的负载计算通过lbscore来完成.这样可以改善Call Storm场景下负载不均衡的现象。
可以通在sqlnet.ora文件中添加监听的trace(TRACE_LEVEL_LISTENER = 16)来获取lbscore的产生情况。
lbscore由两个动态值决定：”goodness” 和 “delta”，这两个值均由PMON来定期更新，计算公式如下：
Delta = New Delta (Received from PMON update)
在PMON定期更新的间隔，应对于每个新连接的建立，监听会自己更新Lbscore，计算公式是：
