alt(7)							 Miscellaneous Information Manual						    alt(7)

NAME

       alt - DEGPA Gigabit Ethernet interface

SYNOPSIS

       config_driver	alt

DESCRIPTION

       The  alt interface provides access to Gigabit Ethernet (1000Mbs) through the DEGPA device.  The interface supports full-duplex operation in
       a switched or point-to-point configuration, and provides the following features:

       The interface has Link Autonegotiation enabled by default. Some switches do not support Link Autonegotiation.  To turn Link Autonegotiation
       off, use the following command: # lan_config -ialt0 -a0 Note that you may add this command to the /etc/inet.local file to preserve the set-
       ting of Link Autonegotiation across system restarts.  JUMBO packets are disabled by default.  JUMBO packets provide a  non-standard  larger
       packet  size.  This enables the interface to carry more data with less CPU overhead.  To enable JUMBO packets, use the following command: #
       ifconfig alt0 ipmtu 9000 Note that there are several interoperability issues with using JUMBO packets (for example,  if	your  switch  goes
       from  1000Mbps  to  a  100Mbps client, JUMBO packets will not work on a 100Mbps LAN).  In order to use JUMBO frames, you will need a switch
       that supports JUMBO frames or a point-to-point configuration with a partner that supports JUMBO frames.	Receive flow control  is  enabled.
       There is currently no way to turn this off.

       Gigabit	Ethernet  performance  with TCP/IP depends on several factors.	Some of the influencing factors are as follows: The speed at which
       data can be delivered to the interface influences throughput.  If your CPU(s) are busy doing several tasks, the task using Gigabit Ethernet
       may  not  get  enough  run time to deliver packets.  In general, faster CPUs will deliver better throughput.  Fast access to the PCI bus is
       critical for high throughput.  Using a 64-bit PCI slot will give you better performance and use less PCI resources than a 32-bit PCI  slot.
       Putting	the  interface on the same PCI bus as other peripherals will degrade throughput.  Each system type may also have different PCI-to-
       host speed considerations (the speed at which the PCI-to-host hardware allows the device to operate).   The  standard  TCP/IP  applications
       (for  example,  ftp and rcp) are not designed to run at Gigabit speeds.	TCP applications that expect performance should use a message size
       of 65000 bytes and a window size of 128000 bytes.  Even when an application is modified to use these settings, high throughput may  not	be
       attainable.  This is particularly true when an application is waiting for data to send (data from a disk, for example).

ERRORS

       The  following  diagnostic and error messages contain relevant information provided by the alt interface, and are displayed to the console.
       Each message begins with the adapter identification, including the number of the adapter.  The alt interface could not  find  adequate  I/O
       addressing on this system to operate.  This is a fatal error, and the DEGPA-SA will not operate on this system.	There was a memory alloca-
       tion problem or the device initialization has failed.  This is indicative of a hardware problem.  Indicates that the Gigabit Ethernet  link
       is  up.	 The Autonegotiated keyword indicates that the link was autonegotiated. Note, this will only be on if autonegotiation is enabled).
       The ReceiveFlowControl keyword indicates that Receive Flow control is enabled on the link.  Indicates that the link  is	no  longer  estab-
       lished.	No communication will occur over the link while it is down.

RELATED INFORMATION

       Commands: ifconfig(8), lan_config(8)

       Files: inet.local(4)

       Network information: arp(7), inet(7), netintro(7) delim off

																	    alt(7)