SQL*Plus Connection Slow and May Yield ORA-03135: Connection Lost Contact
(Doc ID 1639354.1)
Last updated on JANUARY 01, 2020
Applies to:Oracle Net Services - Version 22.214.171.124 and later
IBM AIX on POWER Systems (64-bit)
The problem documented here arose after a change to DNS. It describes a performance issue limited to connect time and does not address any other kinds of performance problems.
The following issue arose on an AIX server running 11gR2.
Following a change to the DNS configuration on this Unix host, the client can no longer establish a connection via the listener. Additionally, connections that are attempted using the local or BEQUEATH protocol are considerably slower.
Here are the tests conducted and a description of the results:
1. Connect to the local instance via the BEQ protocol (without listener).
$ set ORACLE_SID=mysid
$ sqlplus / as sysdba
Very slow to establish a connection but eventually successful
2. Attempt to connect to the local instance via the TCP listener and it will fail:
$ sqlplus myuser@TNS_Alias
SQL*Plus: Release 126.96.36.199.0 Production on Wed Feb 26 14:24:46 2014
Copyright (c) 1982, 2011, Oracle. All rights reserved.
ORA-03135: connection lost contact<=====Fails to connect with 'lost contact'
Process ID: 0
Session ID: 0 Serial number: 0
3. Oracle*Net Trace reveals the following:
4. Nslookup run against the server's hostname yielded the correct results.
5. Ifconfig -a command shows IPv6 was set on loopback interface lo0:
$ ifconfig -a
inet 10.11.12.13 netmask 0xffffff00 broadcast 10.11.12.255
tcp_sendspace 131072 tcp_recvspace 65536 rfc1323 0
inet 127.0.0.1 netmask 0xff000000 broadcast 127.255.255.255
inet6 ::1%1/0 <<===== Note the loopback interface configured with IPv6
The customer recently changed the DNS settings in /etc/netsvc.conf to:
This change would enable both IPv4 and IPv6 DNS searches.
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