Workstation PCI Network

HP-UX 11.0 Extension Pack adds a kernel LAN device driver to support the 100 Base-T networking standard. The 100 Base-T standard provides a network transport rate of 100 Mbits per second over Ethernet LAN media. It supports TCP/IP, SNA, LMX, NetWare and network services (NFS, FTP, telnet, and others).

Newer PA-RISC workstations include LAN interfaces for both 10 Base-T and 100 Base-T standards. The built-in RJ-45 networking port on the rear panel supports both 10 Base-T and 100 Base-T connections (see “RJ-45 and AUI Ports ”). The on-board networking hardware automatically senses the LAN speed and adjusts its operation to the appropriate standard. The enhanced LAN circuitry can handle both full and half duplex operation with auto-negotiation. See “Compatibility”.

You can connect the new platforms into a current 10 Base-T network, or upgrade and connect into a 100 Base-T network.

Summary of Changes

Built-in LAN driver (btlan3) available in Workstation ACE software bundles. Additional changes or features include:
- 10/100 Mbps speed support
- half and full duplex support
- auto-speed sense and auto-negotiation
Filesets added to HP-UX to support 100 Base-T:
- CORE100-KRN for kernel files
- CORE100-RUN for command files
- CORE100-FMT for the nettl formatter
- CORE100-INIT for system initialization and configuration
Configuration specifics.
- System keyword is btlan3
- nettl subsys_id is 173
- Dynamic major number
Support for transports and services
- Support for the current transport stacks (TCP/IP, SNA, LMX, NetWare)
- Support for the current services (NFS, Internet Services)
Patches
- A patch to support 100 CORE functionality
- A patch to support 100 CORE functionality (existing patch
- A patch in SAM to support btlan3 and full duplex options.
- A patch in lanc for schednetisr process launch for high speed links

Impact

Detection and installation will be done by the product scripts. You will be able to connect the new platforms into a current 10 Base-T network, or upgrade and connect into a 100 Base-T network.

Compatibility

The LAN driver supports the current set of transports (TCP/IP and SNA) and services (NFS and Internet Services). The new driver supports cable disconnect, IP Multicast, and Promiscuous Mode.

Manually Configuring Link Speed and Duplex Mode

The networking hardware in the new Workstations is capable of setting its speed and duplex modes via "auto-negotiation" that is, the link will automatically determine the highest-performance setting (100 Mbps FullDuplex, 100 Mbps HalfDuplex, 10 Mbps FullDuplex, 10 Mbps HalfDuplex) of the hub or switch to which it is connected.

Some switches do not implement auto-negotiation or you may wish to manually set the speed and/or duplex mode of the 10/100 Base-T interface and override the auto-negotiation process with a particular switch. Also, manually configuring the speed or duplex setting at the switch may disable the switch from doing auto-negotiation, in which case the speed and/or duplex mode of the 10/100Base-T interface may need to be set manually to match. This may be done in two ways at boot time and via the lanadmin -X command.

At boot time: With this method you may set both the speed and duplex mode of the interface, and have this setting be in effect across subsequent system reboots.

To access the LAN Configuration commands: From the boot console, select the Configuration Menu and from there select LAN Configuration.

From this menu you can configure and display the current mode of the 10/100 Base-T interface using these commands:

LanConfig	Display current configuration settings.
LanConfig 10/Half_dx	Operate in 10 Mbit/s, half duplex mode.
LanConfig 100/Half_dx	Operate in 100 Mbit/s, half duplex mode.
LanConfig 10/Full_dx	Operate in 10 Mbit/s, full duplex mode.
LanConfig 100/Full_dx	Operate in 100 Mbit/s, full duplex mode.
LanConfig AUTO_detect	(default) Enable auto-negotiation
LanConfig AUI	Use the AUI port (10 Mbit/s, half duplex).

If you do not use this method, the system boots up with the default setting "AUTO_Detect".

Via the lanadmin -X command: With this method you may set the speed and duplex mode of the interface. This setting does not persist across system reboots.

To set the duplex mode of the interface, use the -X option of the lanadmin command as follows:

lanadmin -X mode ppa

where mode can be:

10hd (10 half duplex) 
10fd (10 full duplex) 
100hd (100 half duplex) 
100fd (100 full duplex)

ppa is the card instance number of the card, which you can get from the output of the lanscan command.

For example, if the ppa of the 100 Base-T interface is 5, the command to set the interface to 10 full-duplex mode would be:

lanadmin -X 10fd 5

After issuing the lanadmin -X command you must wait at least 8 seconds before attempting to use the specified network interface.

To get the duplex mode of the interface, use the -X option of the lanadmin command as follows:

lanadmin -X ppa

If you want the Duplex Mode setting to be effective in all subsequent reboots, you must create an SD script and include the appropriate command in the /sbin/init.d directory so it gets executed on each reboot.

RJ-45 and AUI Ports

The 10/100 Base-T link works with both an RJ-45 and an AUI port. The RJ-45 port can be used for either 100 Base-T or 10 Base-T networking; the AUI port is used only for 10 Base-T. Only one of these ports should be connected to a network at any given time. The link will normally attempt to automatically sense which port is connected and configure that port, unless this is overridden via the Boot Time LAN configuration described above.

If the RJ45 port is not connected to the network, the system will configure itself to use the AUI port during boot-up or reset.

Performance

The 100 Base-T product is initially set with a conservative value for the Transmit Threshold (that is, the number of bytes that must be in the transmit FIFO buffer before transmission can begin). The Transmit Threshold is set to a "store and forward" value. This means that the entire Ethernet frame must be in the transmit FIFO before transmission of data onto the wire will begin.

The initial Transmit Threshold value is set to eliminate Transmit Underruns (that is, when the transmitter encounters an empty transmit FIFO during the transmission). However, it can also reduce transmit performance by not being able to pre-fetch the next packet until the current frame is completely transferred. This causes a slight delay between frames and subsequently causes an overall drop in transmit performance.

Fortunately, the Transmit Threshold value is adjustable. Adjusting the Threshold to either 1024 or 512 bytes can increase performance. If the Transmit Threshold is 1024 or 512, the CORE 100 Base-T interface will start transmitting data onto the wire after 1024 or 512 bytes are in the transmit FIFO. This allows the CORE 100 Base-T hardware to start pre-fetching the next frame in the transmit FIFO before the current frame is completely transmitted. This results in less time between subsequent frames and therefore increases the transmit performance.

Setting the Transmit Threshold

The CORE 100 Base-T product supports three levels of Transmit Threshold. These three levels are modified via another usage of the -S option of the lanadmin command:

lanadmin -S TransmitThreshold nmid

where

TransmitThreshold of 512 is most aggressive, TransmitThreshold of 1024 is somewhat aggressive, and TransmitThreshold of 1500 is conservative.

After issuing lanadmin -S, you must wait at least 8 seconds before attempting to use the specified network interface.

If you want the Transmit Threshold setting to be effective in all subsequent reboots, you must create an SD script and include the command in the /sbin/init.d directory so it gets executed on each reboot.




	NOTE: Adjusting the Transmit Threshold should be done cautiously. While lowering the Threshold may increase performance, it also makes the CORE 100 Base-T interface more susceptible to Transmit Underrun errors.

A large number of Transmit Underrun errors (more than 1 out of every 1000 packets) may cause a noticeable drop in networking performance. The performance drop will depend on the application being used. Applications that send data in a continuous stream (FTP, for example) 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:

Examine the output from the netstat -I interface command. If the number of output errors is high (more than 1 out of every 1000 packets), the system is most likely suffering from Transmit Underruns on the specified network interface and corrective action must be taken to resolve the problem.
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: It is highly recommended to keep disaster and error nettl logging enabled at all times.
Monitor 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.