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General Information
The configuration of This section provides information on basic aspects of configuring an Ethernet interface for the emulated is described in the basic guest configuration examples above and emulator. For details on the configuration parameters used and for additional parameters, please refer to the Configuration File Reference.
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do not support Jumbo frames. For physical interfaces, this feature must be disabled in the emulator configuration (together with any other offloading parameters) using the initialize_command parameter.
Basic Configuration Components
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The name of the Ethernet interface in the emulator configuration file has the format EWxn XN with the following definitions:
- x is X - an uppercase 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 N - the device number of the card starting with 0 for each value of x.
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EWA0.iface="enp0s20f0u3u4" EWA0.initialize_command="ethtool -K ${IFACE}$IFACE rx off ; ethtool -K ${IFACE}$IFACE tx off ; ethtool -K ${IFACE}$IFACE sg off ; ethtool -K ${IFACE}$IFACE gso off ; ethtool -K ${IFACE}$IFACE gro off ; ethtool -K ${IFACE}$IFACE txvlan off ; ethtool -K ${IFACE}$IFACE rxvlan off" |
The variable IFACE is set automatically by the emulator upon start. The initialize_command parameter is used to turn off all relevant offloading parameters on the interface used by the emulator.
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Adding Additional Emulated Network Cards
Please note: Depending on your model, if / how many additional Ethernet controllers can be loaded depends on the emulated model.
This section will show an example. Please refer to the section I/O Slot Configuration in the Configuration File Reference chapter and the Emulated Model Hardware Configuration Details chapter for details. The present 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 the configuration to load an Ethernet module into the identified emulator slot (see the Configuration File Reference chapter for details).
- Add the network card configuration to your configuration file.
- Start the emulator and configure the interface in the guest system.
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Example: model "rp7400-1-650" has a PCI I/O expansion slot 4 (device path 0/8/0)
Step 2: add 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 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 (important: the initialization command should must 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"
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- On PA3, use the
ISL > ODE > RUN MAPPER2command (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 also use the
lanscancommand 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 documentation of your operating system for further information.
The following image shows a sample of a HPUX HP-UX system with two Ethernet interfaces:
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Basic Bridge Configuration Using ip Commands
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:
| Step | Command |
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| Create a TAP interface (not needed if emulator automatic creation is used). |
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| Activate TAP interface (can also be done via the initialize command in emulator configuration). | # ip link set my_tap0 up |
| Create a new bridge - if needed. | # ip link add name my_bridge type bridge |
| Activate the bridge.bridge - if needed | # ip link set my_bridge up |
| Add If needed, add a physical interface to the bridge as required. This interface will connect the bridge to the physical LAN. | # ip link set <physical-int> master my_bridge |
| Remove any configured IP address from the physical interface. | # ip addr delete <ip-address>/<netmask> dev <physical-int> |
| Add the IP address previously configured on the physical interface (or another IP address to be used by the host system) to the bridge interface. | # ip addr add <ip-address>/<netmask> dev my_bridge |
| Add the TAP interface to the bridge (can also be done via the initialize command in the emulator configuration). | # ip link set my_tap0 master my_bridge |
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To delete TAP and bridge interfaces, you can use the command ip link delete <interface-name>.
Basic Bridge Configuration Using
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nmcli
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 nmcli commands (NetworkManager command-line interface):
| Step | Description |
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| Create If needed, create a bridge and set a static IP address for it. | # nmcli con add type bridge ifname mybr0 ipv4.method manual ip4 <ipaddr/mask> |
| Activate If needed, activate bridge. | # nmcli con up bridge-mybr0 |
| Add If needed, add physical interface to bridge. | # nmcli conn modify <physical-int-conn> master mybr0 slave-type bridge |
| Activate changes to interface. | # nmcli conn up <physical-int-conn> |
After the bridge has been created, you can use the initialize command in the emulator configuration to add the required TAP interfaces for the emulator to the bridge.
Please note: By default, nmicli nmcli commands are persistent (connection information is stored in /etc/sysconfig/network-scripts/).
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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 check, if the module is loaded use the command
# lsmod | grep netfilter
To use the firewall for bridged traffic on newer Linux kernels, the module must be loaded using the command
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or by defining an iptables rule that uses the physdev module.
After If the module has been loaded, the following system configuration parameters are available:
net.bridge.bridge-nf-call-iptablesbridge-nf-call-arptablesbridge-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 (and by default blocks bridged traffic).
Setting the parameters to 0 will disable the firewall rulesfor bridged traffic. They can be set permanently via /etc/sysctl.conf.
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