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General description

It is strongly recommended to use only physical network adapters for CHARON-AXP networking to gain maximum performanceperformances. In situations where the host has only one network adapter, you can use the LINUX Linux virtual network Interfaces ("TUN/TAP") and map individual CHARON-AXP instances to their own virtual interfaces.

There are 2 ways to create the Linux virtual network Interfaces ("TUN/TAP"):

• Using "ncu" utility
• Manually

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. This can be done using the ncu utility.

It is also possible to perform the operations manually. Refer to your Operating System Network Administration guide for details.

Using "ncu" utility to establish CHARON virtual network

Login as root . Start "ncu" and start the ncu utility:

CHARON Network Configuration Utility,  STROMASYS (c) 20162020 Version 1.6 7
 
Interfaces Dedicated to State 
---------- ------------ ----- 
eth0 host connected to host 
eth1 host disconnected from host 
lo host unmanaged from host 
================================================================= 
bridge name bridge id STP enabled interfaces 
========================== VLAN ================================= 
================================================================= 
 select action: 
1 - Dedicate to CHARON 
2 - Release to host 
3 - Create Bridge with TAPs 
4 - Remove Bridge 
5 - Add VLAN 
6 - Remove VLAN 
7 - Print status 
8 - Exit

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In the example above we see 2 virtual network interfaces, "tap0" and "tap1", connected to the created bridge. The physical network interface "eth1" is used for the bridge to the virtual network interfaces.

The interfaces "tap0" and "tap1" are ready to be used in CHARON configurations - , they do not need to be additionally dedicated to CHARON.

Enter "8" to quit the "ncu" utility.

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Manual configuration of CHARON virtual network 

Host preparation

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Configure the physical network interface to run in promiscuous mode using the following command. This interface will be dedicated to the whole network bridge (created later).

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In case the firewall is enabled on the host system, the following command should be executed to allow the bridge to forward IP packets:

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# /sbin/iptable -I FORWARD -m physdev --physdev-is-bridged -j ACCEPT

This command can also be performed from the bridge configuration script. It has to be executed each time the iptables service is (re)started.

It is also possible to make this setting system-wide. Either:

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Virtual interface creation

Creation of the desired number of virtual network interfaces (TAPs) can be performed in the following way:

where “tap<N>” is a name of an instance of the virtual network interface, i.e. “tap0”, “tap1” etc.

Once each virtual network interface instance is created it must be set to promiscuous mode:

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Bridge creation

To interconnect the physical and virtual network interfaces created in the previous step, the network bridge must be introduced in the following way:

where “br0” stands for a name of the created bridge.

Now it is possible to add the network interfaces to the created bridge:

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Example:

The proposed configuration assumes one and only one network bridge, so loops are not possible. It is required to turn off the spanning tree protocol with the following command:

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Starting bridge

To start the created bridge “br0” use the following command:

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