Troubleshooting
Problem
Very slow network traffic on IBM Tivoli Directory Server 5.x or 6.x on an AIX system might occur because the client generates excessive IPV6 DNS lookups for every new connection it makes even if IPV6 is not enabled.
Resolving The Problem
An IBM Tivoli Directory Server version 5.x or 6.x client on AIX generates excessive IPV6 DNS lookups for every new connection it makes, even if IPV6 is not enabled on the client computer or if the numeric address is used. This can cause performance on the network to be very slow.
To fix this problem, disable IPV6 lookups on the client computer by adding the following line to the /etc/netsvc.conf file:
hosts=local4,bind4
To determine whether this is the cause of the network performance problem, you can run an iptrace on the client computer, as follows:
# iptrace -a ./iptrace.out
# ldapsearch -h {any valid IPV4 address or hostname} -s base objectclass=*
# ps -ef | grep iptrace
# kill {PID of the iptrace process; do not kill -9}
Then view the iptrace.out file in Ethereal or use the ipreport command to format the trace.
For example:
Suppose you have an AIX system using an IBM Tivoli Directory Server client with the following configuration:
/etc/resolv.conf file:
nameserver 192.168.1.2
nameserver 192.168.1.3
domain example.austin.texas.com
search example.austin.texas.com austin.texas.com texas.com
/etc/netsvc.conf file:
(default - no settings, just comments)
/etc/hosts file:
127.0.0.1 loopback localhost # loopback (lo0) name/address
192.168.1.100 client # client.example.austin.texas.com
192.168.1.255 ldap # ldap.austin.texas.com
Run the following command:
ldapsearch -h ldap.austin.texas.com -s base objectclass=*
The command generates the following DNS traffic:
No. Time Source Destination Pro Info
184 33.397930 192.168.1.100 192.168.1.2 DNS query A
ldap.austin.texas.com
187 33.400709 192.168.1.2 192.168.1.100 DNS response A
192.168.1.255
188 33.400816 192.168.1.100 192.168.1.2 DNS query AAAA
ldap.austin.texas.com
189 33.403248 192.168.1.2 192.168.1.100 DNS response,
No such name
190 33.403346 192.168.1.100 192.168.1.2 DNS query AAAA
ldap.austin.texas.com.example.austin.texas.com
191 33.403660 192.168.1.2 192.168.1.100 DNS response,
No such name
192 33.403723 192.168.1.100 192.168.1.2 DNS query AAAA
ldap.austin.texas.com.austin.texas.com
193 33.406166 192.168.1.2 192.168.1.100 DNS response,
No such name
194 33.406225 192.168.1.100 192.168.1.2 DNS query AAAA
ldap.austin.texas.com.texas.com
198 40.414418 192.168.1.2 192.168.1.100 DNS response,
No such name
The first query (184) is a normal IPV4 lookup for "ldap.austin.texas.com", which returns "192.168.1.255". But then an IPV6 lookup is done for the same name. Because there is no IPV6 address for ldap.austin.texas.com, it continues searching every search domain in the resolv.conf file (example.austin.texas.com austin.texas.com texas.com) trying to find one.
Historical Number
Work item XX02158;PMR 92625 033 000;APAR IO01196
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Document Information
Modified date:
16 June 2018
UID
swg21212940