Sun Microsystems Sun Quad manual Ipg1 = 8 default at initialization

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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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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 OrganizedUnix Commands Related DocumentsTypographic Conventions Shell PromptsSun Welcomes Your Comments Ordering Sun DocumentsTable P-1SunExpress Contact Information Product Overview 1Sun Quad FastEthernet PCI adapterFeatures 2Sun Quad FastEthernet PCI adapter Back PanelChecking 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 endInstalling the Adapter Verifying the Installation Ok show-devsExamining 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/hostsBooting From the Network At the ok prompt typePost-Installation Procedures Optional Configuring Driver ParametersIncreasing TCP/IP Performance As superuser root, typeForcing Network Speed Between 10 Mbps and 100 Mbps TypeAuto-Negotiation Local-mac-address Property Physical Dimensions SpecificationsTable A-1Physical Dimensions Power Requirements Performance SpecificationsTable A-2Power Requirements Table A-3Performance SpecificationsInterface Signals Ethernet channelsPage Configuring the Quad FastEthernet Device Driver Parameters Internal TransceiverDriver Parameter Values and Definitions Qfe Driver Parameter, Status, and DescriptionsDefining the Current Status Inter-Packet Gap ParametersTable B-1qfe Driver Parameter, Status, and Descriptions Table B-2Read-Only Parameters Defining the Current StatusIpg1 = 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 CapabilitiesReporting the Link Partner Capabilities Table B-8Read-Only Link Partner CapabilitiesSetting qfe Driver Parameters Setting Parameters Using the ndd UtilityTo Specify the Device Instance for the ndd Utility Use the instance number to select the deviceUsing 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 FileSetting Parameters Using the qfe.conf File Setting the ipg1 and ipg2 ParametersSetting ipg Driver Parameters Using a qfe.conf File Etc/pathtoinst fileSet the ipg1 and ipg2 parameters for the above four devices Kernel/drv/qfe.conf fileRunning Diagnostics Tests Using the OpenBoot Prom FCode SelftestRunning the Ethernet FCode Selftest Diagnostic Reset the systemShut down the system Type show-devsto display the list of devicesOk setenv diag-switch? false Set the auto-boot?configuration parameter to true Reset and reboot the systemIndex EditingEditing, 11 example Creating, 12 editing, 11 examplesLEDs Watch-net-all output Page Ordering Sun Documents AIR Mail PAR Avion