HP-UX 11i Version 1 Installation and Update Guide, June 2003

Configuring Built-In PCI Networking
PCI 10/100Base-TX and 100Base-FX/9000
Appendix D208
may have a more noticeable drop in performance (when more than 1 out
of every 1000 packets have errors) than applications which are
request-response in nature (NFS, for example).
Transmit underrun errors may occur on some HP systems when there is
sufficient bus contention from competing I/O devices on the system I/O
bus. These errors can be monitored in two ways:
1. Examine the output from the netstat -I command. If the number of
output errors is high (more than 1 out of every 1000 packets), then
the system is most likely suffering from transmit underruns on the
specified network interface, and corrective action must be taken to
resolve the problem.
2. Turn on nettl errors and warnings for the network interface being
monitored. The following command will turn on disasters, errors and
warnings for the network interface with Instance number 1:
nettl -log 0xe -e base100 -C 1
NOTE Be sure to keep nettl disaster and error logging enabled at all times.
Check the nettl log file /var/adm/nettl.LOG00 for the following message:
HP CORE 10/100BASE-T driver encountered a Transmit Underflow
If a significant number of these messages occur and the timestamps for
each of the messages are within 30 seconds of each other, the specified
networking interface will suffer a noticeable performance drop.
Corrective action must be taken to resolve this problem.
What Happens During Card Initialization Sequence?
Following is an overview of the initialization sequence for the PCI
10/100Base-TX and (for V-Class servers) the 100Base-FX cards.
Initialization of a PCI 10/100Base-TX or 100Base-FX card happens
during system bootup only, and it is driven by the btlan driver for the
card. Whenever initialization fails, it prints a message on the console
identifying the failure. You can later retrieve initialization messages
after the system is fully booted up by using the dmesg command. Finally,
the driver tries to establish a good data link between the card and the
hub or switch.