HP-UX HB v13.00 Ch-09 - Networking Basics

HP-UX Handbook – Rev 13.00 Page 20 (of 27)
Chapter 09 Network Basics
October 29, 2013
Discussing some known problems
Problem: After a reboot the network and the network interfaces are not configured
Before you start “the big troubleshooting procedure”, check /etc/rc.log first for any relevant
information AND check and ensure that the file systems /tmp and /are not full (message: file
system full). Our system requires some space for temporary files in /tmp to initialize the network
stack. If either /tmp or / is full during the boot process, clean it up and restart the system.
Problem: We send a ping request to the broadcast address and get an answer even if the
cable is not plugged in.
Please be aware that if we activate an IP at a NIC we get an answer from this interface to any
ping request to this IP and to the broadcast address of the subnet, even if there is no cable
connected. We need no cable to reach our local interface. We can check the connectivity to the
subnet only through communication to any other system.
When you ping the broadcast check for responses from IP addresses other then the local interface
you are configuring.
Problem: If we check our routing with the traceroute command, we do not see the expected
behavior
Please be aware that all tools have limitations. We have to check our tool first and then the
environment.
Example: If the traceroute command tells you “multiple interfaces found”, when it starts, then
you know that this specific binary version does not automatically use the routing table of the
system. We have to specify the interface using the “-i” option.
Otherwise traceroute will use the first “visible” interface and we cannot test the routing situation
with this tool. If there are only “*” signs in the output instead of time stamps, either your routers
or target system do not send ICMP messages or somewhere in your network a firewall blocks the
ICMP messages.