Ipg1 = 8 default at initialization | Sun Microsystems Sun Quad

TABLE B-3lists the default values and allowable values for the inter-packet gap (IPG) parameters, ipg1 and ipg2.

TABLE B-3Read-Write Inter-Packet Gap Parameter Values and Descriptions

Parameter	Values	Description
	(Byte-time)

ipg1	0, 255	ipg1 = 8 (default at initialization)
ipg2	0, 255	ipg2 = 4 (default at initialization)

By default, the driver sets ipg1 to 8-byte time and ipg2 to 4-byte time, which are the standard values. (Byte time is the time it takes to transmit one byte on the link, with a link speed of either 100 Mbps or 10 Mbps.)

If your network has systems that use longer IPG (the sum of ipg1 and ipg2) and if those machines seem to be slow in accessing the network, increase the values of ipg1 and ipg2 to match the longer IPGs of other machines.

Defining an Additional Delay Before Transmitting a Packet Using lance_mode and ipg0

The PCI Fast Ethernet and Expansion (PFEX) ASIC supports a programmable mode called lance_mode. The ipg0 parameter is associated with lance_mode.

After a packet is received with lance_mode enabled (default) an additional delay is added by setting the ipg0 parameter before transmitting the packet. This delay, set by the ipg0 parameter, is in addition to the delay set by the ipg1 and ipg2 parameters. The additional delay set by ipg0 helps to reduce collisions. Systems that have lance_mode enabled might not have enough time on the network.

If lance_mode is disabled, the value of ipg0 is ignored and no additional delay is set. Only the delays set by ipg1 and ipg2 are used. Disable lance_mode if other systems keep sending a large number of back-to-back packets.

You can add the additional delay by setting the ipg0 parameter from 0 to 31, which is the nibble time delay. Note that nibble time is the time it takes to transfer four bits on the link. If the link speed is 10 Mbps, nibble time is equal to 400 ns. If the link speed is 100 Mbps, nibble time is equal to 40 ns.

For example, if the link speed is 10 Mbps, and you set ipg0 to 20 nibble times, multiply 20 by 400 ns to get 800 ns. If the link speed is 100 Mbps, and you set ipg0 to 30 nibble-times, multiply 30 by 40 ns to get 120 ns.

26 Sun Quad FastEthernet PCI Adapter Installation and User’s Guide • August 1997

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Sun Microsystems Sun Quad manual Ipg1 = 8 default at initialization

Contents

Sun Quad FastEthernet PCI Adapter Installation User’s Guide Please Recycle Regulatory Compliance Statements DOC Class a Notice Avis DOC, Classe a EMC Page Contents Specifications Running Diagnostics Tests Page Preface How This Book Is Organized Unix Commands Related Documents Typographic Conventions Shell Prompts Sun Welcomes Your Comments Ordering Sun DocumentsTable P-1SunExpress Contact Information Product Overview 1Sun Quad FastEthernet PCI adapter Features 2Sun Quad FastEthernet PCI adapter Back Panel Checking the OpenBoot Prom Revision Level Displaying the OpenBoot Prom Revision LevelHardware and Software Requirements 1Hardware and Software RequirementsPage Installing the Adapter Using a text editor, add the following line to the end Installing the Adapter Verifying the Installation Ok show-devs Examining Network Activity Rebooting the System Perform a reconfiguration boot on the systemPage Installing the Driver Software Configuring the Driver SoftwareConfiguring the Host Files Etc/hosts file Reboot your system # cat /etc/hosts Booting From the Network At the ok prompt type Post-Installation Procedures Optional Configuring Driver ParametersIncreasing TCP/IP Performance As superuser root, type Forcing Network Speed Between 10 Mbps and 100 Mbps Type Auto-Negotiation Local-mac-address Property Physical Dimensions SpecificationsTable A-1Physical Dimensions Power Requirements Performance SpecificationsTable A-2Power Requirements Table A-3Performance Specifications Interface Signals Ethernet channelsPage Configuring the Quad FastEthernet Device Driver Parameters Internal Transceiver Driver Parameter Values and Definitions Qfe Driver Parameter, Status, and Descriptions Defining the Current Status Inter-Packet Gap ParametersTable B-1qfe Driver Parameter, Status, and Descriptions Table B-2Read-Only Parameters Defining the Current Status Ipg1 = 8 default at initialization Table B-5Operational Mode Parameters Operational Mode ParametersTable B-4Parameters Defining lancemode and ipg0 Defining the Number of Back-to-Back Packets to Transmit Reporting Transceiver CapabilitiesTable B-6Back-to-back Packet Transmission Capability Table B-7Read-Only Transceiver Capabilities Reporting the Link Partner Capabilities Table B-8Read-Only Link Partner Capabilities Setting qfe Driver Parameters Setting Parameters Using the ndd Utility To Specify the Device Instance for the ndd Utility Use the instance number to select the device Using the ndd Utility in Non-Interactive Mode To modify a parameter value, use the -setoption # ndd /dev/qfe \? Setting Forced Mode Setting Parameters in the /etc/system File Table B-9Setting Variables in the /etc/system File Setting Parameters Using the qfe.conf File Setting the ipg1 and ipg2 Parameters Setting ipg Driver Parameters Using a qfe.conf File Etc/pathtoinst file Set the ipg1 and ipg2 parameters for the above four devices Kernel/drv/qfe.conf file Running Diagnostics Tests Using the OpenBoot Prom FCode Selftest Running the Ethernet FCode Selftest Diagnostic Reset the systemShut down the system Type show-devsto display the list of devices Ok setenv diag-switch? false Set the auto-boot?configuration parameter to true Reset and reboot the system Index EditingEditing, 11 example Creating, 12 editing, 11 examples LEDs Watch-net-all output Page Ordering Sun Documents AIR Mail PAR Avion