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This section provides information on basic aspects of configuring an Ethernet interface for the emulator. For details on the configuration parameters used and for additional parameters, please refer to 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 automatically created 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) using the initialize_command parameter

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	Configuration File Reference
	Configuration File Reference
name	NICGeneral
nopanel	true

Considerations for Cloud Environments

Every cloud environment has specific characteristics that could conflict with the interface configurations made for Charon-PAR. Please refer to the documentation provided by the cloud provider to understand the networking behavior of your cloud instance before you change any interface settings.

Important points that apply to most cloud environments:

If the Charon host is configured with more than one active IP interface, asymmetric routing can cause connectivity problems. In such cases, policy-based routing (per interface routing tables with associated IP rules) is required.
Only IP unicast traffic is supported. Non-IP traffic or multicast/broadcast traffic is not supported and requires traffic tunneling.
Promiscuous interface mode is not supported.
Only traffic with the MAC address assigned by the cloud provider is allowed across an interface.
Routing requires special configuration steps (source/destination check disabling) on the cloud instances. Enabling IP forwarding on the Linux host is not enough.
Cloud specific security rules must allow the relevant traffic. Configuring the Linux firewall correctly is not enough.
If a host NIC is dedicated to a guest system, the MAC address and IP address assigned to the interface by the cloud provider must be used by the guest.

Basic Configuration Components

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

Model 720: system.lan0.card
Model B132L: gsc.lasi.lan.card

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Minimal Configuration Parameters

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

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Interface definition (system.lan0.card.iface or gsc.lasi.lan.card.iface)
Interface initialization command : (system.lan0.card.initialize_command or gsc.lasi.lan.card.initialize_command)

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

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Adding Additional Emulated Network Cards

Please note: if / how many additional Ethernet controllers can be loaded - and how many - depends on the emulated model.

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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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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 also 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 the following:
  - HP-UX before 11.31: 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.

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- - HP-UX 11.31: use SMH > Networking and Communications-> Network Interfaces Configuration > Network Interface Cards. Please note that at the time of writing SMH only worked with the emulator when being used over the network (not on the serial console).
- 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 HP-UX system with two Ethernet interfaces:

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The following shows a sample of the second Ethernet interface being configured on device path 0/8/0/0:

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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
Gather information about the existing network configuration.	List all existing interfaces, their status and their MAC addresses: `# ip link show` List all configured IP addresses and netmasks: `# ip addr show` List the routing table entries: `# ip route show`
Create a TAP interface (not needed if emulator automatic creation is used).	`# ip tuntap add dev my_tap0 mod tap`
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 - if needed	`# ip link set my_bridge up`
If needed, add a physical interface to the bridge. This interface will connect the bridge to the physical LAN (not supported for cloud installations).	`# 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 any routes (including the default gateway) to be routed across the bridge interface - if needed.	`# ip route add <network>/<netmask> via <gwy-IP> dev my_bridge` `# ip route add default via <gwy-IP> 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`

Please note: The commands above are not persistent. They would need to be scripted and added to the host system startup as required.

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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
Gather information about the existing network configuration.	List all existing interfaces, their status and their MAC addresses: `# ip link show` List all configured IP addresses and netmasks: `# ip addr show` List the routing table entries: `# ip route show`
If needed, create a new connection for the physical interface to be used with the bridge.	`# nmcli conn add type ethernet autoconnect yes \ con-name <physical-int-name> \ifname <pysical-int-name> ip4 0.0.0.0`
If needed, create a bridge and set a static IP address for it.	`# nmcli con add type bridge autoconnect yes \ con-name``mybr0` `ifname` `mybr0` \ `ipv4.method manual ip4` <ipaddr/mask> `stp off`
If needed, activate bridge.	`# nmcli con up bridge-mybr0`
If needed, add physical interface to bridge (not supported for cloud installations).	`# 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 let the emulator create a TAP interface automatically and use the initialize command in the emulator configuration to add the required TAP interfaces interface for the emulator to the bridge.

Please note: By default, nmcli commands are persistent (. The connection information is stored in /etc/sysconfig/network-scripts/).

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if the default plugin in
/etc/NetworkManager/NetworkManager.conf is ifcfg-rh. It is stored in /etc/NetworkManager/system-connections/ if the default plugin is keyfile. Permanent TAP connection information is always stored in the NetworkManager directory unless the network-scripts package is used for configuration.

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Basic Emulator Configuration Using a TAP Interface

The following example shows how to use a TAP interface in the emulator configuration, where the interface is automatically created and removed by the emulator. The initialization command adds the interface to an existing bridge named my_bridge:

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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 for bridged traffic. 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.

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Setting the parameters to 0 will disable the firewall for bridged traffic. 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.

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Supplemental Information: MACVTAP Interfaces (since version 3.0.9)

In some cloud environments, interface settings on the Linux level are not passed properly to the NIC on the cloud level. This can cause problems with network connectivity and, in particular, with network performance. The problem can be solved by using a virtual bridge between host and guest, and by configuring routing or NAT to allow guest communication with other systems. However, such configurations are often complex due to the fact that only the cloud-assigned MAC and IP addresses can be used. On a virtual bridge to which host and guest are attached, this condition cannot be met.
MACVTAP interfaces provide an alternative solution - they are linked to a host NIC and are TAP based. However, when used in passthrough mode, they can use the same MAC and IP address as assigned by the cloud provider.

Basic (non-persistent) configuration of a MACVTAP interface on the Linux host system:

Activate the NIC that is dedicated to the emulator:

# ip link set <nic-name> up

Remove IPv4 and IPv6 addresses from the NIC:

# ip addr flush <nic-name>

# ip -6 addr flush <nic-name>

Create a MACVTAP interface linked to the host NIC:

# ip link add link <nic-name> name <macvtap0> type macvtap mode passthru

Configure the correct MTU on the new interface:

# ip link set dev macvtap0 mtu 1500

Activate the new interface:

# ip link set macvtap0 up

Set the correct permissions on the underlying TAP interface:

# chown ${USER} /dev/tap`cat /sys/class/net/macvtap0/ifindex`

Basic (persistent) configuration of a MACVTAP interface on the Linux host system using nmcli commands:

If desired rename connection:

# nmcli conn mod <old-connection-name> con-name <new-connection-name>

Remove IP address from physical interface and configure automatic interface activation at boot:

# nmcli conn mod <new-connection-name> ipv4.method "disabled" ipv6.method "disabled"

# nmcli conn mod <new-connection-name> connection.autoconnect yes

Activate changes on physical interface (this command may time-out if IP connection test is configured)

# nmcli con up <new-connection-name>

Create MACVTAP interface, disable the IP configuration and activate the interface:

# nmcli conn add type macvlan mode passthru dev <physical-NIC> tap yes autoconnect yes con-name macvtap0 ifname macvtap0

# nmcli conn mod macvtap0 ipv4.method "disabled" ipv6.method "disabled"

# nmcli con up macvtap0

Basic emulator configuration using a MACVTAP interface:

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language	text

EWA0.mapping_mode = "MACVTAP"
EWA0.iface = "macvtap0"

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Versions Compared

Old Version 36

New Version Current

Key

Considerations for Cloud Environments

Basic Configuration Components

Minimal Configuration Parameters

Adding Additional Emulated Network Cards

Basic Emulator Configuration Using a TAP Interface

Supplemental Information: MACVTAP Interfaces (since version 3.0.9)

Page Comparison

Versions Compared

Old Version 36

New Version Current

Key

Considerations for Cloud Environments

Basic Configuration Components

Minimal Configuration Parameters

Adding Additional Emulated Network Cards

Basic Emulator Configuration Using a TAP Interface

Supplemental Information: MACVTAP Interfaces (since version 3.0.9)