决定配置客户端sqlnet.ora，增加下面的参数以对连接情况进行跟踪：
LOG_FILE_CLIENT = sjapp.txt
TRACE_DIRECTORY_CLIENT = /tmp
TRACE_LEVEL_CLIENT = 16

分析跟踪文件：

1、从跟踪文件发现客户端一开始通过1521端口建立了连接：
[06-MAR-2008 12:20:23:586] niotns: Calling address: (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=10.1.160.198)(PORT=1521)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=orcl)(CID=(PROGRAM=sqlplus)(HOST=bfe-test)(USER=oracle))))
[06-MAR-2008 12:20:23:586] nscall: entry
[06-MAR-2008 12:20:23:586] nsmal: entry
[06-MAR-2008 12:20:23:586] nsmal: 224 bytes at 0x80000001002a0278
[06-MAR-2008 12:20:23:586] nsmal: normal exit
[06-MAR-2008 12:20:23:586] nscall: connecting...
[06-MAR-2008 12:20:23:586] nladini: entry
[06-MAR-2008 12:20:23:586] nladini: exit
[06-MAR-2008 12:20:23:586] nladget: entry
[06-MAR-2008 12:20:23:586] nladget: exit
[06-MAR-2008 12:20:23:587] nsc2addr: entry
[06-MAR-2008 12:20:23:587] nttbnd2addr: entry
[06-MAR-2008 12:20:23:587] nttgetport: entry
[06-MAR-2008 12:20:23:587] nttgetport: port resolved to 1521
[06-MAR-2008 12:20:23:587] nttgetport: exit
[06-MAR-2008 12:20:23:587] nttbnd2addr: using host IP address: 10.1.160.198
[06-MAR-2008 12:20:23:587] nttbnd2addr: exit
[06-MAR-2008 12:20:23:587] nsc2addr: normal exit
[06-MAR-2008 12:20:23:587] nsopen: entry
[06-MAR-2008 12:20:23:587] nsmal: entry
[06-MAR-2008 12:20:23:587] nsmal: 800 bytes at 0x80000001002aa360
[06-MAR-2008 12:20:23:587] nsmal: normal exit
[06-MAR-2008 12:20:23:587] nsopenmplx: entry
[06-MAR-2008 12:20:23:587] nsmal: entry
[06-MAR-2008 12:20:23:587] nsmal: 2592 bytes at 0x80000001002aa698
[06-MAR-2008 12:20:23:587] nsmal: normal exit
[06-MAR-2008 12:20:23:587] nsopenmplx: normal exit
[06-MAR-2008 12:20:23:587] nsopen: opening transport...
[06-MAR-2008 12:20:23:587] nttcon: entry
[06-MAR-2008 12:20:23:588] nttcon: toc = 1
[06-MAR-2008 12:20:23:588] nttcnp: entry
[06-MAR-2008 12:20:23:588] nttcnp: creating a socket.
[06-MAR-2008 12:20:23:588] nttcnp: exit
[06-MAR-2008 12:20:23:588] nttcni: entry
[06-MAR-2008 12:20:23:588] nttcni: trying to connect to socket 10.
[06-MAR-2008 12:20:23:637] nttcni: connected on ipaddr 11.1.60.94
[06-MAR-2008 12:20:23:637] nttcni: exit
[06-MAR-2008 12:20:23:637] nttcon: NT layer TCP/IP connection has been established.
2、然后服务器端发出信息要求客户端与下面的地址通信：
(HOST=202.21.198.2)(PORT=1695)
3、客户端在试图与上面的地址通信时失败：
[06-MAR-2008 12:20:23:764] nttgetport: port resolved to 1695
[06-MAR-2008 12:20:23:764] nttgetport: exit
[06-MAR-2008 12:20:23:764] nttbnd2addr: using host IP address: 202.21.198.2
[06-MAR-2008 12:20:23:764] nttbnd2addr: exit
[06-MAR-2008 12:20:23:764] nsc2addr: normal exit
[06-MAR-2008 12:20:23:764] nsopen: entry
[06-MAR-2008 12:20:23:764] nsmal: entry
[06-MAR-2008 12:20:23:764] nsmal: 800 bytes at 0x80000001002aa360
[06-MAR-2008 12:20:23:764] nsmal: normal exit
[06-MAR-2008 12:20:23:764] nsopenmplx: entry
[06-MAR-2008 12:20:23:764] nsmal: entry
[06-MAR-2008 12:20:23:764] nsmal: 2592 bytes at 0x80000001002aa698
[06-MAR-2008 12:20:23:764] nsmal: normal exit
[06-MAR-2008 12:20:23:765] nsopenmplx: normal exit
[06-MAR-2008 12:20:23:765] nsopen: opening transport...
[06-MAR-2008 12:20:23:765] nttcon: entry
[06-MAR-2008 12:20:23:765] nttcon: toc = 1
[06-MAR-2008 12:20:23:765] nttcnp: entry
[06-MAR-2008 12:20:23:765] nttcnp: creating a socket.
[06-MAR-2008 12:20:23:765] nttcnp: exit
[06-MAR-2008 12:20:23:765] nttcni: entry
[06-MAR-2008 12:20:23:765] nttcni: trying to connect to socket 10.
[06-MAR-2008 12:21:40:055] ntt2err: entry
[06-MAR-2008 12:21:40:055] ntt2err: soc 10 error - operation=1, ntresnt[0]=505, ntresnt[1]=238, ntresnt[2]=0
[06-MAR-2008 12:21:40:055] ntt2err: exit
[06-MAR-2008 12:21:40:055] nttcni: exit
[06-MAR-2008 12:21:40:055] nttcon: exit
[06-MAR-2008 12:21:40:055] nserror: entry
[06-MAR-2008 12:21:40:055] nserror: nsres: id=0, op=65, ns=12535, ns2=12560; nt[0]=505, nt[1]=238, nt[2]=0; ora[0]=0, ora[1]=0, ora[2]=0
[06-MAR-2008 12:21:40:055] nsopen: unable to open transport
[06-MAR-2008 12:21:40:055] nsbfr: entry
[06-MAR-2008 12:21:40:055] nsbfr: normal exit
[06-MAR-2008 12:21:40:055] nsbfr: entry
[06-MAR-2008 12:21:40:055] nsbfr: normal exit
[06-MAR-2008 12:21:40:055] nsmfr: entry
[06-MAR-2008 12:21:40:055] nsmfr: 2592 bytes at 0x80000001002aa698
[06-MAR-2008 12:21:40:055] nsmfr: normal exit
[06-MAR-2008 12:21:40:056] nsmfr: entry
[06-MAR-2008 12:21:40:056] nsmfr: 800 bytes at 0x80000001002aa360
[06-MAR-2008 12:21:40:056] nsmfr: normal exit
[06-MAR-2008 12:21:40:056] nsopen: error exit
[06-MAR-2008 12:21:40:056] nsmfr: entry
[06-MAR-2008 12:21:40:056] nsmfr: 171 bytes at 0x80000001002ae548
[06-MAR-2008 12:21:40:056] nsmfr: normal exit
[06-MAR-2008 12:21:40:056] nsmfr: entry
[06-MAR-2008 12:21:40:056] nsmfr: 224 bytes at 0x80000001002a0278
[06-MAR-2008 12:21:40:056] nsmfr: normal exit
[06-MAR-2008 12:21:40:056] nladtrm: entry
[06-MAR-2008 12:21:40:056] nladtrm: exit
[06-MAR-2008 12:21:40:056] nscall: error exit
[06-MAR-2008 12:21:40:056] nioqper: error from nscall
[06-MAR-2008 12:21:40:056] nioqper: nr err code: 0
[06-MAR-2008 12:21:40:056] nioqper: ns main err code: 12535
[06-MAR-2008 12:21:40:056] nioqper: ns (2) err code: 12560
[06-MAR-2008 12:21:40:056] nioqper: nt main err code: 505
[06-MAR-2008 12:21:40:056] nioqper: nt (2) err code: 238
[06-MAR-2008 12:21:40:056] nioqper: nt OS err code: 0
[06-MAR-2008 12:21:40:056] niomapnserror: entry
[06-MAR-2008 12:21:40:056] niqme: entry
[06-MAR-2008 12:21:40:057] niqme: reporting NS-12535 error as ORA-12535
[06-MAR-2008 12:21:40:057] niqme: exit
[06-MAR-2008 12:21:40:057] niomapnserror: returning error 12535
[06-MAR-2008 12:21:40:057] niomapnserror: exit
[06-MAR-2008 12:21:40:057] niotns: Couldn't connect, returning 12535
8、无法ping通202.21.198.2
9、显然连接的时候，服务器端使用了Redirected Session的方式，而新的IP地址对客户端而言不能建立连接。