数据库版本 oracle 11.2.0.4

操作系统Redhat 7.6

主库rac两节点，备库rac两节点，级联备库单机（级联备库需要主库切归档级才能同步数据）

从备库rac搭建级联备库单机，启动mrp进程会报

Error 12154 received logging on to the standby

具体报错如下：这个现象正常吗？

Tue Jun 28 15:10:07 2022
alter database recover managed standby database using current logfile disconnect from session
Attempt to start background Managed Standby Recovery process (adg)
Tue Jun 28 15:10:07 2022
MRP0 started with pid=20, OS id=84545
MRP0: Background Managed Standby Recovery process started (adg)
Serial Media Recovery started
Managed Standby Recovery starting Real Time Apply
Waiting for all non-current ORLs to be archived...
All non-current ORLs have been archived.
Media Recovery Waiting for thread 2 sequence 19
Error 12154 received logging on to the standby
FAL[client, MRP0]: Error 12154 connecting to orcl,orcldg for fetching gap sequence
Completed: alter database recover managed standby database using current logfile disconnect from session

级联备库相关参数（log_archive_dest_2未设置）：

*.fal_server='orcl,orcldg'
*.fal_client='adg'
*.log_archive_config='DG_CONFIG= (orcl,orcldg,adg)'
*.log_archive_dest_1='LOCATION=USE_DB_RECOVERY_FILE_DEST VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=adg'