While you can create or redirect links even when the nodes involved in the link are
running as part of a simulation, it is only possible to create a link if the nodes at
either end of the link each have an unused interface available. Once a node has been
started, the number of interfaces allocated to that node cannot be changed until the
node is stopped and wiped. This restriction means that link creation and
interface creation behave differently once you have started a node.
If you add a node to the canvas and have not started it yet, or if you have wiped a node
and not started since wiping it, the Workbench automatically adds
additional interfaces to a node to accommodate new links. You may also add extra
interfaces directly to a node. Each node definition has a maximum possible number of
interfaces. If the node is not at the maximum number of allocated interfaces for its
node definition, you can select it as the source or destination of a link. If all of the
allocated interfaces are used by existing links, the Workbench
permits you to select an unallocated interface for the connection, and it allocates that
interface to the node when you create the connection. If the node already has its
maximum number of interfaces allocated, and all of the interfaces are in use, then it is
not possible to create a new link with that node.
If a node is currently running as part of a simulation, or if the node is stopped but has
associated simulation state that has not been wiped, then the number of interfaces
allocated to that node cannot be changed. If at least one of the interfaces allocated to
the node is unused, then you can select it as the source or destination of a link. If
all of the interfaces allocated to the node are used by existing links, then it is not
possible to create a new link with that node even if the node has fewer allocated
interfaces than its maximum number of allowed interfaces. Before you can add a link or
interface to such a node, you must stop and wipe the node.
Tip |
To avoid having to stop a node in your simulation or to recreate its state after
wiping it, you may want to overprovision interfaces on the nodes in your
labs. Overprovisioning interfaces means allocating more interfaces on a node than it
needs for the existing links in the topology. If you overprovision the interfaces on
the nodes in your lab, each node has at least one unused interface when you first
start the simulation. These extra interfaces enable you to add additional nodes and
links to your lab later without having to stop or wipe any of the existing nodes in
the lab.
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Because interfaces consume system resources, CML only allocates
additional interfaces to a node when the interfaces are needed for a new link. Each node
definition has a default initial number of interfaces. When you first drag-and-drop a
node into the lab, the node will have the default number of interfaces allocated to it.
In smaller topologies, the default number of interfaces may create some modest
overprovisioning, but if you want to overprovision interfaces in your lab, you should
check all nodes before starting the lab to ensure that each one has enough unused
interfaces allocated to each node.
Tip |
If you cannot create a connection to a node, select the node and then click the
Interfaces tab in the bottom pane of the
Workbench. If the button in the top-left of the
Interfaces pane indicates Max Interfaces
Reached, then the node has reached the maximum number of interfaces
possible for that node type. If the button is disabled but indicates Add
# Interfaces, then additional interfaces can be added to the node,
but the node must be stopped and wiped first.
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