155 lines
6.2 KiB
Markdown
155 lines
6.2 KiB
Markdown
# CORE Control Network
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## Overview
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The CORE control network allows the virtual nodes to communicate with their
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host environment. There are two types: the primary control network and
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auxiliary control networks. The primary control network is used mainly for
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communicating with the virtual nodes from host machines and for master-slave
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communications in a multi-server distributed environment. Auxiliary control
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networks have been introduced to for routing namespace hosted emulation
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software traffic to the test network.
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## Activating the Primary Control Network
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Under the *Session Menu*, the *Options...* dialog has an option to set a
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*control network prefix*.
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This can be set to a network prefix such as *172.16.0.0/24*. A bridge will
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be created on the host machine having the last address in the prefix range
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(e.g. *172.16.0.254*), and each node will have an extra *ctrl0* control
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interface configured with an address corresponding to its node number
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(e.g. *172.16.0.3* for *n3*.)
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A default for the primary control network may also be specified by setting
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the *controlnet* line in the */etc/core/core.conf* configuration file which
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new sessions will use by default. To simultaneously run multiple sessions with
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control networks, the session option should be used instead of the *core.conf*
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default.
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!!! note
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If you have a large scenario with more than 253 nodes, use a control
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network prefix that allows more than the suggested */24*, such as */23* or
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greater.
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!!! note
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Running a session with a control network can fail if a previous
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session has set up a control network and the its bridge is still up. Close
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the previous session first or wait for it to complete. If unable to, the
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**core-daemon** may need to be restarted and the lingering bridge(s) removed
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manually.
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```shell
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# Restart the CORE Daemon
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sudo /etc/init.d core-daemon restart
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# Remove lingering control network bridges
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ctrlbridges=`brctl show | grep b.ctrl | awk '{print $1}'`
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for cb in $ctrlbridges; do
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sudo ifconfig $cb down
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sudo brctl delbr $cb
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done
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```
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!!! note
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If adjustments to the primary control network configuration made in
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**/etc/core/core.conf** do not seem to take affect, check if there is anything
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set in the *Session Menu*, the *Options...* dialog. They may need to be
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cleared. These per session settings override the defaults in
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**/etc/core/core.conf**.
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## Control Network in Distributed Sessions
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When the primary control network is activated for a distributed session, a
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control network bridge will be created on each of the slave servers, with
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GRE tunnels back to the master server's bridge. The slave control bridges
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are not assigned an address. From the host, any of the nodes (local or remote)
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can be accessed, just like the single server case.
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In some situations, remote emulated nodes need to communicate with the host
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on which they are running and not the master server. Multiple control network
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prefixes can be specified in the either the session option or
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*/etc/core/core.conf*, separated by spaces and beginning with the master
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server. Each entry has the form *"server:prefix"*. For example, if the servers
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*core1*,*core2*, and *core3* are assigned with nodes in the scenario and using
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*/etc/core/core.conf* instead of the session option.
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```shell
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controlnet=core1:172.16.1.0/24 core2:172.16.2.0/24 core3:172.16.1.0/24
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```
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Then, the control network bridges will be assigned as follows:
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* core1 = 172.16.1.254 (assuming it is the master server),
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* core2 = 172.16.2.254
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* core3 = 172.16.3.254
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Tunnels back to the master server will still be built, but it is up to the
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user to add appropriate routes if networking between control network prefixes
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is desired. The control network script may help with this.
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## Control Network Script
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A control network script may be specified using the *controlnet_updown_script*
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option in the */etc/core/core.conf* file. This script will be run after the
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bridge has been built (and address assigned) with the first argument being the
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name of the bridge, and the second argument being the keyword *"startup"*.
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The script will again be invoked prior to bridge removal with the second
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argument being the keyword *"shutdown"*.
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## Auxiliary Control Networks
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Starting with EMANE 0.9.2, CORE will run EMANE instances within namespaces.
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Since it is advisable to separate the OTA traffic from other traffic, we will
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need more than single channel leading out from the namespace. Up to three
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auxiliary control networks may be defined. Multiple control networks are set
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up in */etc/core/core.conf* file. Lines *controlnet1*, *controlnet2* and
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*controlnet3* define the auxiliary networks.
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For example, having the following */etc/core/core.conf*:
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```shell
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controlnet = core1:172.17.1.0/24 core2:172.17.2.0/24 core3:172.17.3.0/24
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controlnet1 = core1:172.18.1.0/24 core2:172.18.2.0/24 core3:172.18.3.0/24
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controlnet2 = core1:172.19.1.0/24 core2:172.19.2.0/24 core3:172.19.3.0/24
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```
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This will activate the primary and two auxiliary control networks and add
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interfaces *ctrl0*, *ctrl1*, *ctrl2* to each node. One use case would be to
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assign *ctrl1* to the OTA manager device and *ctrl2* to the Event Service
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device in the EMANE Options dialog box and leave *ctrl0* for CORE control
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traffic.
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!!! note
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*controlnet0* may be used in place of *controlnet* to configure
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the primary control network.
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Unlike the primary control network, the auxiliary control networks will not
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employ tunneling since their primary purpose is for efficiently transporting
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multicast EMANE OTA and event traffic. Note that there is no per-session
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configuration for auxiliary control networks.
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To extend the auxiliary control networks across a distributed test
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environment, host network interfaces need to be added to them. The following
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lines in */etc/core/core.conf* will add host devices *eth1*, *eth2* and *eth3*
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to *controlnet1*, *controlnet2*, *controlnet3*:
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```shell
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controlnetif1 = eth1
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controlnetif2 = eth2
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controlnetif3 = eth3
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```
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!!! note
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There is no need to assign an interface to the primary control
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network because tunnels are formed between the master and the slaves using IP
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addresses that are provided in *servers.conf*.
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Shown below is a representative diagram of the configuration above.
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