Networking

General description

CHARON-AXP supports emulation of the following network adapters:

DE435
DE450
DE500AA
DE500BA
DE602
DE602AA

Each of them is a PCI Ethernet adapter based on the DEC21040 (DE435, DE450, DE500AA and DE500BA) and the Intel i8255x (DE602 and DE602AA) PCI Ethernet adapter chips for the HP Alpha.

CHARON-AXP maps the virtual adapter to a dedicated Ethernet adapter in the Linux host system.

All the emulated controllers are loaded and configured in the same way.

The Ethernet adapter in the Linux host system must support dynamic changes of its MAC address (i.e. no reboot of the host system is required to change the MAC address), which is the case with nearly all modern Ethernet adapters.

By default the PCI Ethernet adapters use first available PCI slot. If instead some particular slot is needed, refer to this section for details of specific placement of PCI peripherals on CHARON-AXP PCI bus.

Configuration steps

To configure CHARON-AXP networking, follow these 3 steps:

Load network adapter (if required)
Use the "load" command as shown below.

Example:
For DEC21040 adapters For Intel i8255x adapters
load DE500BA/dec21x4x NIC
load DE602/i8255x NIC

In AlphaStation 400 configuration use the following syntax for network adapter loading:
load DE500AA/dec21x4x NIC irq_bus=isa
By default each loaded virtual network adapter uses first available PCI slot. If instead some particular slot is neded, refer to this section for details of specific placement of PCI peripherals on CHARON-AXP PCI bus.
Load "packet_port" or "tap_port"
Load "packet_port" or "tap_port" to connect network adapter to the host hardware network card (or to a virtual network interface).

Example:
load packet_port/chnetwrk NDIS interface = "eth1"
Connect the loaded "packet_port" ("tap_port") to the loaded virtual network adapter
Connect the network adapter to the "packet_port" ("tap_port") by setting the interface name.

Example:
set NIC interface = NDIS

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Configuration parameters

Each virtual network controller has the following parameters that are specified with the "set" command:

interface

Parameter	interface
Type	Text String
Value	Name of the corresponding instance of the "packet_port" or "tap_port" component

station_address

Parameter station_address

Type

Text String

Value

The "station_address" provides the ability to configure the adapter’s permanent address. By default the adapter’s permanent address is read from the host system’s NIC.

Format:

XX-XX-XX-XX-XX-XX

or

XX:XX:XX:XX:XX:XX

Example:

set EWA station_address="AF:01:AC:78:1B:CC"

rx_fifo_size

Parameter

rx_fifo_size

Type

Numeric

Value

"rx_fifo_size" sets the receive FIFO size.

The value is specified in Kb and, by default, is pre-calculated from the connected port’s size of the receive queue.

Typically, you do not need to change the "rx_fifo_size" parameter. It is available for extended tuning and debugging purposes.

adapter_mode

Parameter adapter_mode

Type Text String

Value

Defines the link speed and the duplex settings of the virtual network adapter (except for DE602/DE602AA - see below).

The values are:

Parameter	Description
"Auto"	Auto-negotiate (default)
"10BaseT-HD"	10Mbps half duplex
"10BaseT-FD"	10Mbps full duplex
"100BaseT-HD"	100Mbps half duplex
"100BaseT-FD"	100Mbps full duplex

Defines the link speed and the duplex settings of the virtual network adapter (except for DE602/DE602AA - see below).

The values are:

Example:

set EWA adapter_mode="100BaseT-HD"

Example

load packet_port/chnetwrk EWA0 interface = "eth1"
set EWA interface = EWA0
set EWA station_address="0C:FE:35:AA:67:3B"

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DE602 and DE602AA network adapters link speed and duplex settings

Regardless of the "adapter_mode" setting in CHARON-AXP configuration file (see above), DE602 and DE602AA network adapters remains in "Auto-negotiation" mode, since the EIDRIVER of OpenVMS checks for EIx0_MODE environment variable when configuring the network card.

So mode propagation is implemented in CHARON-AXP via SRM console EIx0_MODE environment variable ("x" is A, B, C... depending on CHARON-AXP configuration), for example:

>>>help set

usage: set <variable-name> <value>
set <variable-name> ""

set eia0_mode { Twisted | Full | Fast | FastFD | Auto* }

>>>

The EIx0_MODE variable name is case insensitive, while its values are case sensitive! This is feature of OpenVMS EIDRIVER.

The values are:

Parameter	Description
"Auto"	Auto-negotiate (default)
"Twisted"	10Mbps half duplex
"Full"	10Mbps full duplex
"Fast"	100Mbps half duplex
"FastFD"	100Mbps full duplex

Example:

>>>set eia0_mode FastFD

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Packet Port

The CHARON-specific "packet_port" interface establishes a connection between an Ethernet adapter in the Linux host system and a network adapter in the virtual HP Alpha system.

For every virtual adapter instance loaded, one dedicated host Ethernet physical adapter is required.

To create instances of the "packet_port", use the “load” command in the configuration file as follows:

load packet_port/chnetwrk <instance-name>

Example:

load packet_port/chnetwrk pp1

"packet_port" uses several configuration parameters to control its behavior.

interface

Parameter interface

Type

Text string

Value

This parameter identifies an Ethernet adapter of the host system dedicated to CHARON-AXP.

Syntax:

set <name> interface="<adapter>"

Example:

set pp1 interface="eth1"

port_enable_mac_addr_change

Parameter

port_enable_mac_addr_change

Type Boolean

Value

If "true" is specified (default value), CHARON-AXP sets the appropriate Ethernet address automatically.

If "false" is specified, set the Ethernet address manually.

Example:

set pp1 port_enable_mac_addr_change=false

port_retry_on_tx

Parameter

port_retry_on_tx

Type Numeric

Value

The "port_retry_on_tx" parameter controls the number of times a port will attempt to transmit a packet before giving up.

By default, the value is 3.

Increasing this value may introduce problems in carrier loss logic, because not all NIC drivers support a carrier status query.

Typically, you do not need to increase the value.

Example:

set pp1 port_retry_on_tx=8

port_pending_rx_number

Parameter

port_pending_rx_number

Type Numeric

Value

The "port_pending_rx_number" parameter sets the number of pending receive buffers.

The default value is 63. The maximum value allowed is 195.

You may want to increase the "port_pending_rx_number" when you have very busy networking and experience problems like losing connections not related to the carrier loss.

Typically, you do not need to change this parameter.

Example:

set pp1 port_pending_rx_number=128

port_pending_tx_number

Parameter

port_pending_tx_number

Type Numeric

Value

The "port_pending_tx_number" parameter sets the number of buffers the port uses to transmit.

The default value is 62.

You may want to increase the "port_pending_tx_number" value if the log file indicates dropped TX packets due to TX queue overflow.

Typically, you do not need to change this parameter.

Example:

set pp1 port_pending_tx_number=128

Example

load DE500BA/dec21x4x EWA load packet_port/chnetwrk pp1 interface="eth1"
set EWA interface=pp1

CHARON-AXP supports VLAN adapters. If for some reasons you are going to use them, proceed with their installation and configuration according to the network adapter's vendor's User's Guide and then use the resulting VLAN interface the same way as the regular network interface.

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