.. This file is part of the CORE Manual
   (c)2012-2013 the Boeing Company

.. _Machine_Types:

*************
Machine Types
*************

.. index:: machine types

Different node types can be configured in CORE, and each node type has a
*machine type* that indicates how the node will be represented at run time.
Different machine types allow for different virtualization options.

.. _netns:

netns
=====

.. index:: netns machine type

The *netns* machine type is the default. This is for nodes that will be
backed by Linux network namespaces. See :ref:`Linux` for a brief explanation of
netns. This default machine type is very lightweight, providing a minimum 
amount of
virtualization in order to emulate a network. 
Another reason this is designated as the default machine type
is because this virtualization technology
typically requires no changes to the kernel; it is available out-of-the-box
from the latest mainstream Linux distributions.

.. index:: physical machine type

.. index:: emulation testbed machines

.. index:: real node

.. index:: physical node

.. _physical:

physical
========

The *physical* machine type is used for nodes that represent a real
Linux-based machine that will participate in the emulated network scenario.
This is typically used, for example, to incorporate racks of server machines
from an emulation testbed. A physical node is one that is running the CORE
daemon (:file:`core-daemon`), but will not be further partitioned into virtual
machines. Services that are run on the physical node do not run in an
isolated or virtualized environment, but directly on the operating system.

Physical nodes must be assigned to servers, the same way nodes
are assigned to emulation servers with :ref:`Distributed_Emulation`.
The list of available physical nodes currently shares the same dialog box
and list as the emulation servers, accessed using the *Emulation Servers...* 
entry from the *Session* menu.

.. index:: GRE tunnels with physical nodes

Support for physical nodes is under development and may be improved in future
releases. Currently, when any node is linked to a physical node, a dashed line
is drawn to indicate network tunneling. A GRE tunneling interface will be
created on the physical node and used to tunnel traffic to and from the
emulated world.

Double-clicking on a physical node during runtime 
opens a terminal with an SSH shell to that
node. Users should configure public-key SSH login as done with emulation
servers.

.. _xen:

xen
===

.. index:: xen machine type

The *xen* machine type is an experimental new type in CORE for managing
Xen domUs from within CORE. After further development, 
it may be documented here.

Current limitations include only supporting ISO-based filesystems, and lack
of integration with node services, EMANE, and possibly other features of CORE.

There is a :file:`README-Xen` file available in the CORE source that contains
further instructions for setting up Xen-based nodes.