HP-UX LAN Administrator's Guide (Feburary 2007)

DRAFT COPY Troubleshooting HP-UX LAN
Diagnostic Flowcharts
Chapter 5 55
Subnet Test: Verifies the correct use of subnets.
Figure 5-1 Loopback Tests
The loopback tests shown in Figure 5-1 are used to isolate a network communication problem
that may be software- or hardware-related. In any case, you should first have checked that
the problem is not due to a recent configuration change.
The network level loopback test, ping, commonly is tried first. It is fast, efficient, and it does
not require superuser privileges. If the connection passes this test, you know the problem is at
OSI Layer 4 or above. Go on to the transport level loopback test.
The Transport Level Loopback Test can be implemented using Internet Services. In this case,
you use telnet and ftp to systematically focus on a problem.
If the network level loopback test failed, the problem is in OSI Layer 3 or below. In this case,
continue with the link level loopback test, using linkloop or nwmgr --diag, to isolate a
problem to OSI Layer 2 or below.
UDP
IP
LAN Driver
Network Interface Card
ARP
TCP
BSD Sockets
Virtual
NFS Services
DLPI
Terminal
Internet Services
1
2
3
6 & 7
5
4
lanadmin
ICMP
MAU
XTI
OSI Layer
telnet showmount
(NFS)
ping
linkloop
or nwmgr