Contents

General Information

The configuration of an Ethernet interface for the emulated is described in the basic guest configuration examples above and the Configuration File Reference.

The emulated Ethernet interfaces of Charon-PAR can be linked either to a

• physical host interface, or
• to a TAP interface on the host.

Notes for TAP interfaces:

• A TAP interface can either be created by the user or will be created automatically by the emulator if it does not already exist.
• For automatically created TAP interfaces, the user can specify a name or let the emulator select a name.
• A TAP interface is not automatically added to a bridge, this must be configured via the initialize_command.
• An automatically created TAP interface is deleted automatically upon emulator stop.

By default, emulated models have one Ethernet device. Depending on the model, more Ethernet devices can be added.

The emulated network devices

• DE 500 PCI based cards (for 64-bit systems), and

• LASI-82596 cards (for the 32-bit system)

do not support Jumbo frames. For physical interfaces, this feature must be disabled in the emulator configuration (together with any other offloading parameters).

Basic Configuration Components

Ethernet Interface Names

Names on 64-bit systems:

The name of the Ethernet interface in the emulator configuration file has the format EWxn with the following definitions:

• x is an upercase letter starting with A for the first interface and then continues with B, C, etc. for additional interfaces. The possible number of network cards depends on the features of the original physical system. The absolute maximum number is 16.
• n is the device number of the card starting with 0 for each value of x.

Names on 32-bit systems:

The currently supported 32-bit system supports only one Ethernet card named system.lan0.card.

Minimal Configuration Parameters

The configuration of each network interface must at least have two basic components as shown below:

64-bit system (example shows the first Ethernet card EWA0):

• Interface definition (EWA0.iface)
• Interface initialization command: (EWA0.initialize_command)

32-bit system:

• Interface definition (system.lan0.card.iface)
• Interface initialization command: (system.lan0.card.initialize_command)

The default configuration assumes that a physical network interface will be used.

Please refer to the Configuration File Reference and the configuration template of your model for more information.

Basic Configuration Example

Example of a basic network card configuration using a physical interface on a 64-bit emulated system:

EWA0.iface="enp0s20f0u3u4"
EWA0.initialize_command="ethtool -K ${IFACE} rx off ; ethtool -K ${IFACE} tx off ; ethtool -K ${IFACE} sg off ; ethtool -K ${IFACE} gso off ; ethtool -K ${IFACE} gro off ; ethtool -K ${IFACE} txvlan off ; ethtool -K ${IFACE} rxvlan off"

The variable IFACE is set automatically by the emulator upon start.

Adding Additional Emulated Network Cards

Please note: Depending on your model, additional Ethernet controllers can be loaded. Please refer to the section I/O Slot Configuration in this Configuration File Reference chapter. This section will show an example.

To add an additional Ethernet controller to your emulator configuration, you must perform the following steps:

• Identify a free PCI slot (model configuration template or Emulated Model Hardware Configuration Details).
• Add a load command to load an Ethernet module into the identified emulator slot.
• Add the network card configuration to your configuration file.
• Start the emulator and configure the interface in the guest system.

Step 1: identify a free PCI slot for your emulated model. The available slots depend on your model and the existing configuration.

Example: model "rp7400-1-650" has a PCI I/O expansion slot 4 (device path 0/8/0)

Step 2: add the load command for the Ethernet module to the configuration file.

Sample configuration command for slot 4:  load ETH tulip PCI 4

Step 3: add the network card configuration to your configuration file selecting the correct host interface name (example: eth2). Note that the name of the second emulated interface is EWB0.

Example (the initialization command should be in one continuous line):

EWB0.iface="eth2" 
EWB0.initialize_command="ethtool -K $IFACE rx off;
ethtool -K $IFACE tx off; ethtool -K $IFACE sg off; ethtool -K $IFACE gso off;
ethtool -K $IFACE gro off; ethtool -K $IFACE txvlan off; ethtool -K $IFACE rxvlan off" 

Step 4: Start the emulator, boot the guest system and configure the second interface.

• On PA3, use the ISL > ODE > RUN MAPPER2 command (access from console via: Interaction with IPL) to verify the existence of the new interface and the correct device path.
• The above command also works on PA9, but on HP-UX you can use the lanscan command to verify the existence of the new interface (on HP-UX it is normally lan1).
• Configure the interface.
  • The easiest way on HP-UX is to use SAM > Network and Communication > Network Interface Cards (Actions > Configure).
  • On MPE/iX, the interface must be added via NMMGR (for interactive use, xhpterm can be used to access this tool), and the interface must be started using the NETCONTROL command. Please refer to the documenation of your operating system for further information.

The following image shows a sample of a HPUX system with two Ethernet interfaces:

Supplemental Information: Virtual Bridge and TAP Interfaces

Basic Bridge Configuration

The following table shows a simple example of how to create a virtual bridge on Linux and how to add TAP interfaces to it using ip commands:

Linux Firewalls and Virtual Bridges

If firewall rules are to be used for bridged traffic, the kernel can be instructed to apply iptables (also arptables and ip6tables) rules to bridged traffic. In older versions, this option was included in the bridge functionality itself. Starting with kernel 3.18, the filtering functionality in the form of the br_netfilter module was moved into a separate module that can be loaded by the user if required. If the module is not loaded, no firewall rules are applied to bridge traffic and no further actions are required to pass the bridged traffic through the Linux host system.

To use the firewall for bridged traffic on newer Linux kernels, the module must be loaded using the command

# modprobe br_netfilter

or by defining an iptables rule that uses the physdev module.

After the module has been loaded, the system configuration parameters

• net.bridge.bridge-nf-call-iptables
• bridge-nf-call-arptables
• bridge-nf-call-ip6tables

become available.

They are set to 1 by default (equivalent to echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables). This value enables iptables rules for bridged traffic.

Setting the parameters to 0 will disable the firewall rules. They can be set permanently via /etc/sysctl.conf.

To allow bridged traffic through the enabled firewall, use commands like the following:

# firewall-cmd --permanent --direct --add-rule ipv4 filter INPUT 1 \

-m physdev --physdev-is-bridged -j ACCEPT

# firewall-cmd --permanent --direct --add-rule ipv6 filter INPUT 1 \

-m physdev --physdev-is-bridged -j ACCEPT

# firewall-cmd --reload

Please refer to the documentation of your host system for more detailed information.

Please note: at the time of writing, this feature is not yet available for nftables.