AIX 5L Problem Determination - IBM Redbooks

command ping -f (flood ping) requires root access to the system. For every
ECHO_REQUEST sent, a period '.' is printed, while for every ECHO_REPLY
received, a backspace is printed. This provides a rapid display of how many
packets are being dropped.
If the ping is not successful, you need to:
1. Ensure that the inetd process is actively using the lssrc -g tcpip command.
If inetd is not active, issue the startsrc -s inetd or startsrc -g tcpip
command.
# lssrc -g tcpip
Subsystem Group PID Status
routed tcpip 5424 active
inetd tcpip 6192 active
snmpd tcpip 6450 active
gated tcpip inoperative
named tcpip inoperative
----- the output was edited for brevity -----
2. Check the state of the loopback interface (lo0) with the netstat -i
command. If you see lo0* in the output, check the /etc/hosts file for an
uncommented local loopback entry, as follows:
# netstat -I lo0 -n
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll
lo0* 16896 link#1 412934 0 414344 0 0
lo0* 16896 127 127.0.0.1 412934 0 414344 0 0
lo0* 16896 ::1 412934 0 414344 0 0
# grep localhost /etc/hosts
127.0.0.1 loopback localhost # loopback (lo0) name/address
A splat (*) after the interface name in the output from the netstat command
indicates that the interface is down. Use the following command to start the
lo0 interface:
# ifconfig lo0 inet 127.0.0.1 up
If you cannot reach a host that is in a different network, you can check the
connection using the traceroute command. The traceroute command output
shows each gateway that the packet traverses on its way to finding the target
host. If possible, examine the routing tables of the last machine shown in the
traceroute output to check if a route exists to the destination from that host. The
last machine shown is where the routing is incorrectly set.
# traceroute 9.3.240.56
traceroute to 9.3.240.56 (9.3.240.56), 30 hops max, 40 byte packets
1 server4e (10.47.1.1) 1 ms 1 ms 0 ms
2 server1 (9.3.240.56) 1 ms 1 ms 1 ms
Chapter 8. Network problem determination 183