5. Advanced Usage

5.1 Extended Network Scenario

In this section we will show how to extend the simple network topology (see Section 4.1). We will explain the additional possibilities of building and configuring the extended network scenario:

The simple network topology is placed in the office-canvas while the additional elements are placed in the roadwarrior-canvas. The roadwarrior-canvas consists of a router (roadwarrior-router), a PC (roadwarrior) and a physical interface. The roadwarrior-router is connected to the office-router on the office-canvas through the network, the PC is in the network whereas the physical interface is in the network.

We will now extend the simple network from the last chapter by adding the roadwarrior-router, roadwarrior and the physical interface all placed on another canvas. To open an existing IMUNES network configuration file use File $\to$ Open from the menubar or start IMUNES with the imn file as an argument: imunes simple-topology.imn. Check that you are in the edit mode. If not, switch with Experiment $\to$ Terminate.

5.1.1 Canvas Management

To facilitate building of complex and large network topologies IMUNES lets you divide the network topology into a set of network layers. These network layers are called canvases.

Canvas management consists of two main elements:

To add a new canvas use the Canvas $\to$ New option from the menubar or double click on the empty space in the canvas tabs list at the bottom of the window.

You can rename the canvas with the Canvas $\to$ Rename option from the menubar or double click on the canvas tab in the canvas tabs list. (Figure 5.2) Similarly the Canvas $\to$ Delete option deletes the active canvas.

Figure 5.2: Canvas rename dialog

Image canvas_rename

There is also the option Canvas $\to$ Resize that allows you to define a custom canvas size in pixels. The default canvas size is 900*620 pixels. (Figure 5.3)

Figure 5.3: Canvas resize dialog

Image canvas_resize

Canvas selection can be done with the options from the Canvas menu (Previous, Next, First, Last) or simply by clicking the tab with the canvas name on it.

Rename the existing canvas Canvas0 into office-canvas. Add a new canvas, rename it into roadwarrior-canvas and select it as the active canvas.

This canvas is empty so we will add a router by selecting the router tool and clicking on the empty canvas. Rename this router into roadwarrior-router. Switch to the office-canvas. Now we will connect the office-router and the roadwarrior-router. To do that, right click on the office-router and select Create link to $\to$ roadwarrior-canvas $\to$ roadwarrior-router option (Figure 5.4) from the popped up menu. This will create a link between roadwarrior-router and office-router.

Figure 5.4: Create link to

Image create_link_to

On the office-router set the eth2 interface IPv4 address to On the roadwarrior-router set the eth0 interface IPv4 address to We will add another PC to the roadwarrior-canvas, name it roadwarrior and connect it with the roadwarrior-router. On the roadwarrior set the eth0 IPv4 address to On the roadwarrior-router set the eth1 IPv4 address to

The roadwarrior-router uses the same dynamic routing model (quagga) as the office-router and we do not need to configure anything else on the router. The roadwarrior uses static routes and we will need to change the default route gateway in static routes field of the roadwarrior configuration window to

Finally, the configured network topology should look like the following (Figure 5.5 and Figure 5.6):

Figure 5.5: office-canvas
Image office_canvas

Figure 5.6: roadwarrior-canvas
Image roadwarrior_canvas

Both the roadwarrior and roadwarrior-router can be easily moved from roadwarrior-canvas to office-canvas with the Move To $\to$ office-canvas from the node menu. The link between roadwarrior-router and office-router, as well as any other link, can be deleted with the Delete option from the Link menu. To open the link menu, use the right click on the link and choose the Delete option.

When we are done with network configuration, we can start the experiment with Experiment $\to$ Execute from the menubar. We can now check that the roadwarrior can ping both networks (, and additionally, that the network does not have an access to the roadwarrior, but it has access to the network.

5.1.2 Attaching an external interface

The External interface tool from the toolbox provides the possibility to attach a physical interface to a virtual node. This way the virtual network is able to communicate with nodes from the external network.

We will now add the external interface to the roadwarrior-canvas. To add a external interface to the canvas select the External interface tool and click on the canvas.

External interface nodes can be connected either with the LAN switch or the router. Connect the newly created external interface with the virtual node roadwarrior-router using the Link tool from the toolbox or the Create link to option from the node menu.

The newly created external interface node is unassigned and in the node name field it contains UNASSIGNED. Open the external interface configuration window with a double click or right click on it and select the Configure option. Choose the name of the designated physical interface in the Physical interface drop-down list, e.g. em1, obtained from ifconfig -a command ran on the physical machine (outside IMUNES). (Figure 5.7) The name of the physical interface will appear in the node name label. It is also possible to assign a VLAN tag to it. (Figure 5.8)

Figure 5.7: External interface configuration dialog
Image rj45_conf

Figure 5.8: External interface node label

Image rj45_canvas

Check that roadwarrior-router has a properly configured IP address on the network interface connected to the physical interface. Additionally, check that routes which route packets between virtual network and the external network through the physical interface exist in both the external network and in the virtual network (on roadwarrior-router).

Save this configuration to a new file by selecting the Save as option from the File menu. Name the file extended-topology.imn.

5.1.3 Attaching to a running experiment

IMUNES gives you the possibility to run multiple independent experiments on one physical computer. Therefore, we added the possibility of attaching to running experiments through the IMUNES GUI. In the Experiment menu, select the option Attach to experiment. A dialog similar to 5.9 is opened. Here you can select on which experiment you would like to attach. You can attach to all experiments, those that were started using batch mode and those that were executed from the GUI. The window shows the following experiment parameters:

To attach to the you can double-click it's entry or use the Resume selected experiment button.

Figure 5.9: Attach to experiment window

Image attach_to_experiment

5.2 Additional Configuration

5.2.1 Custom configuration

The configuration window of each network layer node (PC, Host, Router, NAT64 and Click router) also has the Custom startup configuration field. In order to view or edit the generated startup configuration click on the Editor button as shown in Figure 5.10.

Figure 5.10: Configuration tab

Image configuration_tab

In a newly opened window, write a new configuration name and click Create. An empty configuration file will be created. By clicking on Fill defaults, in case of a non-router network layer node or a router node with the static routing model, the default configuration consists of ifconfig and route commands with the /bin/sh shell. Figure 5.11 shows the created default configuration.

Figure 5.11: Custom configuration window

Image custom_configuration

It is possible to add custom commands that will be executed at the boot time. When finished, click on the Apply or Apply and Close button to save the changes. When you have multiple configurations, you can choose the default one in the Default configuration drop-down menu. To delete a configuration, select its tab and click Delete config button.

NOTE: After starting the network simulation, the new/custom configuration will be considered only if Custom startup configuration is enabled. This is done by checking the Enabled check box in the Custom startup config field in Figure 5.10.

5.2.2 Physical and logical interfaces

When the Interfaces tab is opened, a configuration window similar to the one shown in Figure 5.12 is shown to the user. The Physical Interfaces list represents actual interfaces connected to links in IMUNES. Thus we can see that the selected node has one link in IMUNES.

IMUNES also offers the feature to configure additional logical interfaces. By default only one logical interface is added: lo0 - the loopback interface with the following addresses: for IPv4 and ::1 for IPv6.

Figure 5.12: Physical and logical interfaces

Image physical_logical_interfaces

Users can configure additional logical interfaces by clicking on the Logical Interfaces item in the Interfaces list. The Logical Interfaces configuration window is show in Figure 5.13. At the moment IMUNES supports two types of logical interfaces: lo and vlan.

Figure 5.13: Logical interfaces management

Image logical_interfaces

Figure 5.14 shows an example for setting up a vlan logical interface vlan0 on a physical interface eth0 with an arbitrary tag 10 and an IPv4 address

Figure 5.14: Logical interfaces management

Image vlan_logical_interfaces

5.3 Additional Tools

5.3.1 Splitting a link

Links can be split in two separate parts and it is possible to change location of both of its parts after selecting it with the Select tool. Right click on the link and than left click on the Split label in the pop-up menu to split the link in two halves. Separated link parts can be merged back with the Merge option from the link menu. This feature is shown in Figure 5.15.

Figure 5.15: Split link

Image split_link

5.3.2 Generating a network topology

TopoGen menu from the menubar enables easier and faster generation of network topologies (Figure 5.16). This function can be used to generate following topologies: Chain, Star, Cycle, Wheel, Cube, Clique, Bipartite or Random.

Figure 5.16: TopoGen menu

Image topogen_menu_star

Some examples can be seen in Figure 5.17, Figure 5.18 and Figure 5.19. In order to generate a topology first select the network layer nodes (router, host or PC) from the toolbox and then the desired topology type e.g. bipartite graph K(2,3) (see Figure 5.18).

Figure 5.17: Star topology

Image star

Figure 5.18: Bipartite topology
Image bipartite

Figure 5.19: Wheel topology
Image wheel

In case of random topology an additional information is needed, so beside the number of the nodes it is also necessary to specify the number of links. The nodes in the random topology will be randomly connected with the number of links specified before. An example of generating a random topology:

  1. Select the router tool from the toolbox.
  2. Choose the random topology: TopoGen $\to$ Random
  3. Choose the desired number of nodes and links e.g. n = 6; m = 5, where n is the number of nodes and m the number of links in the generated network topology (Random $\to$ R(6,m) $\to$ R(6,5)).
The result is shown in Figure 5.20.

Figure 5.20: Random topology

Image random

Using the TopoGen tool you can generate topologies containing one type of node (router, host or PC). In that case, new nodes of the same type are created and placed on the canvas. Another option is to add new nodes to canvas and then connect them using the topology generator:

  1. Add nodes to the canvas (don't have to be same type).
  2. Select nodes that should be included in the new topology
  3. Right click on one of the selected nodes and choose the option Create Link to from the menu. Choose the option Selected and select one of the offered topologies (Chain, Star, Cycle, Clique or Random). An example is shown in Figure 5.21.

In addition to that, it is also possible to transform existing nodes:

  1. Select nodes that should be transformed
  2. Right click on one of the selected nodes and choose the option Transform to from the menu. Select one of the offered options (Router, PC or Host). An example is shown in Figure 5.22.

Figure 5.21: Example of creating a network topology with existing nodes

Image connect_1connect_2

Figure 5.22: Example of transforming existing network layer nodes

Image transform

5.3.3 IPv4 address pool

IPv4 address pool option from the Tools menu is used for replacing default address pool. Choosing that option invokes a dialog shown in Figure 5.23.

Figure 5.23: IPv4 address pool dialog

Image ipv4_addr_pool

In order to replace default address pool, set variable-mask IPv4 address pool through the invoked dialog. CIDR notation is required, so the IPv4 address needs to be followed by a slash and a network length. To apply changes click on the Apply button. The given address pool will be applied to all the subsequentially created network layer elements (Figure 5.24).

Figure 5.24: IPv4 address pool example

Image ipv4_addr_pool_example

In order to apply the given address pool to selected elements, right click on the network layer element and choose the option IPv4 autorenumber from the popped up menu. In example shown in Figure 5.25 we have set IPv4 address pool to, selected all network elements and selected the option IPv4 autorenumber from the node menu to apply the given address pool to selected elements.

Figure 5.25: IPv4 autorenumber example

Image ipv4_autorenumber_example

5.3.4 IPv6 address pool

IPv6 address pool option from the Tools menu is used for replacing default fc00::/64 address pool. The procedure for setting the IPv6 address pool is the same as for setting the IPv4 address pool.

5.3.5 Routing protocol defaults

In the Tools menu you can find the Routing protocol defaults option. Selecting this option invokes a popup window shown in Figure 5.26. Just as a reminder, settings referring to routing protocols can be also changed in the router configuration window. The difference is that changes made there are applied only to the router that is being configured. This tool in contrary makes it possible to apply changes to one or more selected routers. If there is no router selected than the changes will be applied to subsequentially created routers. Note that this option will be disabled when the experiment starts.

Figure 5.26: Router defaults window

Image router_defaults_1

5.4 Customizing Look

5.4.1 Annotations

To emphasize some parts of the network topology, you can add various graphic elements to the canvas. These elements are divided into three groups: Each of these elements have their own tools in the toolbox: Text tool (Figure 5.27), Freeform tool (Figure 5.28), Oval tool (Figure 5.29) and Rectangle tool (Figure 5.30).

Figure 5.27: Text tool

Image text_tool

Figure 5.28: Freeform tool

Image freeform_tool

Figure 5.29: Oval tool

Image oval_tool

Figure 5.30: Rectangle tool

Image rectangle_tool

To add an annotation to the canvas, select the appropriate tool and click (and drag) where you want to add the annotation. A popup window will be shown. There you can define how will the annotation look.

When created, annotations can be moved around on the canvas. This is done by using the select tool. Click on the annotation and then drag it to its destination. Text

The text annotation lets you define the following options(Figure 5.31):

Figure 5.31: Text configuration window

Image text_conf Freeform

The freeform configuration window includes:

Figure 5.32: Freeform configuration window

Image freeform_conf Oval

The size of the oval annotation is defined by dragging the cursor on the canvas while keeping the left mouse button pressed. When the annotation size seems to be fine, release the mouse button. The oval configuration window will popup (Figure 5.33).

The oval annotation lets you define the following additional options (Figure 5.33):

Figure 5.33: Oval configuration window

Image oval_conf Rectangle

The rectangle configuration window has the same options as the oval configuration window. The rectangle size is defined the same way as the size of the oval.

The rectangle annotation lets you define the following additional options (Figure 5.34):

Figure 5.34: Rectangle configuration window

Image rectangle_conf

Example of the annotations usage is shown in Figure 5.35.

Figure 5.35: Annotations example

Image annotations_example

5.4.2 Canvas background image

The options for changing the canvas background image are accessible through the Canvas and View menu and through the menu that is opened with a right click on the empty canvas (Figure 3.6 and Figure 5.36).

Figure 5.36: Background image menu

Image background_image_menu

All options related to the canvas background are accessible in the Background image menu (Figure 5.36):

To set a canvas background you need to open the Change canvas background window (Figure 5.37).

Figure 5.37: Change canvas background

Image change_canvas_background

This window is divided into two main parts:

Figure 5.38: Warning if ImageMagick is not present

Image imagemagick_warning

When the image is selected there are four image setting modes that can be chosen: Settings canvas background images

We will use the extended topology example (extended-topology.imn) to set canvas background images. On the office-canvas we will set a background image. Then we will go to the roadwarrior-canvas and set that same image using the Set background from $\to$ office-canvas option (Figure 5.39).

Figure 5.39: Set background from menu

Image set_background_from

The final result is shown in Figure 5.40 and Figure 5.41.

Figure 5.40: Canvas background example on office-canvas
Image canvas_background_example_1

Figure 5.41: Canvas background example on roadwarrior-canvas
Image canvas_background_example_2

5.4.3 Icons

IMUNES lets you choose custom node icons. First, select the nodes whose icons you want to change. Then right click on the selection and then go to the Node icon $\to$ Change node icons option (Figure 5.42). This menu has also the Set default icons option that sets the default node icon for the selected icons.

Figure 5.42: Node icon menu

Image node_icon_menu

The Change node icons option opens the Set custom icon window (Figure 5.43).

Figure 5.43: Set custom icon

Image set_custom_icon

This window is divided into two main parts (Figure 5.43):

We will now open the extended-topology.imn file and set a custom icon. We will choose the library icon ipfirewall.gif for the roadwarrior-router. The final result is shown on Figure 5.44.

Figure 5.44: Changed roadwarrior-router icon

Image changed_node_icon Icon size

If you want to emphasize the information about nodes, interfaces and links instead of node icons you can change the icon size through the View $\to$ Icon size option (Figure 5.45).
Figure 5.45: Icon size menu

Image icon_size

Let's take the simple-topology.imn example and set the icon size to small. (Figure 5.46)

Currently, only two sizes are available, normal and small. Otherwise, custom icons can be used.

Figure 5.46: Icon size example

Image icon_size_example

5.5 User-configurable Event Scheduling

This section describes a feature for scheduling of arbitrary deterministic and stochastic events during experiment execution.

5.5.1 Principle of operation

The control plane in IMUNES is extended to retain control over the experiment execution after initial topology instantiation, allowing for user-scheduled events to influence selected parameters during run time. The current implementation allows for the event scheduler to assume control over selected link properties such as:

The event scheduler supports two general classes of schedulable events: one-time changes and periodic functions.

One-time events update the selected parameter at requested point in time, leaving that parameter constant throughout rest of the experiment execution, or until another event updates it to a new value at some later point in time.

Periodic functions allow for time-variant functions to be applied to selected parameters by specifying those functions as single events. Subsequently scheduled events acting upon the same parameter will cancel the current periodic function and replace it with either a constant value or another periodic function.

5.5.2 Configuring events with events editor

Events can be specified in the Events editor (Figure 5.47). To open the Events editor select the Events $\to$ Events editor option. The editor is divided into two elements. The left side element contains a list of all links. The right side element contains events configured on the selected link. This dialog allows you to edit events on that link. To save the event scheduling configuration you need to click on Apply button. The events editor gives you the possibility to start or stop the event scheduling during experiment execution. This can be also done from the Events menu in the menubar.

Figure 5.47: Events editor

Image event_editor

Each event entry occupies a single line of text, consisting of four fields: deadline, target parameter, function and function parameters. The first field, deadline, is specified as an integer number of seconds since experiment instantiation. The second field, target parameter, may be one of the following: bandwidth, delay, ber, duplicate, width or color. The remainder of the line is further parsed as a function. The type of the function is determined by the leading keyword, which may be either const, ramp, rand or square. When saving the configuration through the events editor a syntax check will be performed. If the syntax is wrong the configuration will not be saved and a popup dialog will show the first line that has a syntax error. Const

The const function accepts one parameter, the target value. After the deadline time the parameter will constantly be equal to the target value. Ramp

Behavior of the ramp function is determined by three arguments: initial value, delta, and period, which are all integers. The first argument represents the initial function value. The second is the delta value, which may be both positive or negative, which is added to the previous value of the function at each period. The third argument is the period, determining how often will the delta value be added to the current function value. Rand

The rand function is determined by three arguments: lower bound, upper bound, and period; all of which are integers. The function will assume a random value between lower and upper bound after each period (in seconds) expires. Square

Finally, the square function has three arguments as well: low value, high value, and period; all integer numbers. The resulting function will flip from low value to high and vice versa after each period (in second) expires. Example

The following example illustrates a possible event scheduling scenario that can be entered in the Event editor window (Figure 5.47):

    30 bandwidth ramp 128000 8000 2
    30 delay rand 80000 120000 8
    60 delay square 100000 200000 10
    60 ber const 1
    90 ber const 0
    120 delay const 0

At t = 30 s, bandwidth of the selected link will be set to 128 Kbps, and will continue to grow at a rate of 8 Kbps each 2 s.

Also at t = 30 s, the delay will begin assuming a random value between 80 ms and 120 ms, and will continue to change the setting to new random values in the same range each 8 s.

At t = 60 s, the delay will cease to assume random values, and instead it will begin to oscillate between two discrete values, 100 ms and 200ms, each 10 s.

Also at t = 60 s, the bit error rate (BER) will be set to 1, resulting in all frames traversing the link to be silently dropped.

At t = 90 s, the BER is reset back to 0, allowing for all frames to traverse the link without artificial losses.

At t = 120 s, the oscillation of the delay parameter will stop, and delay will be reset to 0 ms for the rest of the experiment execution time.

The current time is shown on the status bar after the zoom value. (Figure 4.17)

5.5.3 Configuring events through configuration file

NOTE: It is advised to use the Events editor to configure event scheduling because it includes a syntax check. In the case of configuring events through configuration file, the wrong syntax will be silently ignored.

IMUNES experiments are defined via plain-text configuration files, which currently describe virtual nodes and links, as well as additional objects related only to GUI visual properties and annotations. The other way to configure events is manual editing of an existing configuration file.

The example bellow shows a configuration section describing a virtual link in an IMUNES experiment. The link l0 connects virtual nodes n0 and n1, has the bandwidth constraint set to 128 Kbps, and has the thickness of the line representing the link in the GUI set to 6 pixels. All of the mentioned properties are directly controllable via the IMUNES GUI. The configuration for link l0 also includes an empty placeholder for schedulable events, meaning that no events have been programmed for this link.

link l0 {
    width 6
    nodes {n0 n1}
    bandwidth 128000
    events {

The events section in the configuration file accepts the same commands as does the Events editor in the GUI.

5.6 Starting and terminating a simulation through CLI

In addition to the File$\to$Open option to open an .imn file and the Experiment$\to$Execute option used to initiate the virtual network topology in the GUI, the simulation can be initiated through the command-line interface (CLI) with the following command:

# imunes -b simple-network.imn

Using IMUNES through GUI, the Experiment$\to$Terminate option is used for shutting down the simulation and cleaning up the virtual network topology from the kernel. The CLI alternative for the latter is the following command:

# imunes -b -e experimentId

The parameter exeperimentId represents the experiment identifier. In order to get the experiment identifier you can use the himage command. With himage -l you will get a list of identifiers of all started experiments.

5.7 Managing virtual nodes (jails) - jls, jexec

The FreeBSD jail mechanism allows partitioning of a FreeBSD-based computer system into several independent smaller systems called jails. This mechanism enables creation of a safe environment, separate from the rest of the system. Processes created inside a jail are limited within that jail environment. Each jail is a virtual environment running on the host machine, having its own file system, processes, set of users, networking subsystem of the FreeBSD kernel and a few other things.

Two main commands exist in FreeBSD for manging and configuring previously created jails:

A virtual image or vimage is a jail with its own independent network stack instance. Every process, socket and network interface present in the system is always attached to one, and only one, virtual network stack instance (vnet). During system bootup sequence a default vnet is created to which all the configured interfaces and user processes are initially attached.

The jexec command allows for execution of arbitrary processes in a targeted virtual image.

jexec jname command ...

The jexec command starts the selected command and it's arguments in the jail jname.

To find out the names of started jails the jls command is used:

jls [-hnqsv] [parameter ...]

Since the default jls command doesn't list names of jails a better output is provided using the command:

jls -h jid name host.hostname

Also, the command jls -v gives a more detailed output.

5.7.1 Examples

Execute the ifconfig command in the jail with the jail name n1:

# jexec n1 ifconfig

Execute the csh command in the IMUNES virtual node named host1:

First we need to find out the jail ID or jail name to execute the wanted command:

# jls -h jid name host.hostname | grep host1

The first parameter output is the jail ID, the second is the jail name and the last is the hostname. To execute the command you need the jail ID or jail name:

# jexec jid csh

# jexec jname csh

5.8 Himage tool

The jls and jexec commands can be impractical for creating scripts for topologies since the output of the jls command is needed for starting the jexec command. The jexec command can't take the hostname of the jail as an argument, it can only take the jail name or jail id. The jail name is created from the IMUNES experiment ID and the node identifier (not hostname). Every experiment started in IMUNES has a different randomly generated experiment ID to enable execution of multiple experiments at once.

IMUNES comes with the himage tool that enables the usage of hostnames when starting commands in virtual nodes. The himage tool starts the jexec command with the appropriate jail name so that the user doesn't have to search for it.

The himage command has the following options:

5.8.1 Examples

Example of usage of the command himage on a node with the hostname "pc" to get a list of running processes:

# himage pc ps ax

If there are multiple experiments running and there are nodes with the same hostnames in these experiments the himage command accepts the following node specification where vi_hostname is specified as hostname@eid, where eid is the experiments' ID.

# himage hostname@eid command ...


# himage pc@i3d05a ps ax

where i3d05a is the experiment ID of the running experiments. To find out which experiments are running the himage -l command can be used as well as jls -h jid name host.hostname.

Execute the ifconfig command the IMUNES node named server:

# himage server ifconfig

5.9 Hcp tool

While the himage command is used for running programs inside virtual nodes the hcp is used to copy files directly to the filesystem of running mobile nodes, thus simplifying deployment of configuration files for starting various services on virtual nodes.

Usage of the command hcp:

hcp [cp_command_options] [vi_hostname1:]filename [vi_hostname2:]filename

The hcp command invokes the cp command with the specified options. If the vi_hostname1 is specified the script copies a file from the virtual node, otherwise it copies a file from the local folders. The second vi_hostname2 specifies on which node the first file will be copied, if not specified the file is copied to the local folders.

vi_hostname is specified in the same way as in the himage command, hostname or hostname@eid.

5.9.1 Examples

Copy file dhcpd.conf from a local folder to the virtual node DHCP:

# hcp dhcpd.conf DHCP:/usr/local/etc/

Copy file message.txt from the virtual node PC to a local folder:

# hcp PC:/root/message.txt .

Copy file index.html from the virtual node HOST to the virtual node HTTP:

# hcp HOST:/usr/local/www/data/index.html HTTP:/usr/local/www/data/

5.10 Example (himage and hcp)

This is an example of starting an DHCP server through a script with the provided configuration file dhcpd.conf.

Kill the server if it's started:

# himage DHCP killall -9 dhcpd

Copy the configuration file:

# hcp dhcpd.conf DHCP:/usr/local/etc/

Create the .leases file defined in dhcpd.conf:

# himage DHCP touch /var/db/dhcpd.leases

Start the sever with the copied configuration file:

# himage DHCP dhcpd -cf /usr/local/etc/dhcpd.conf

5.11 Vlink tool

The vlink tool is used to change link parameters. The following link parameters are available:

A link is identified by the endpoint node names. The link between pc1 and pc2 is identified by pc1-pc2 or pc2-pc1.

Usage of the command vlink:

vlink [options] link_name[@eid]

5.11.1 Examples

Setting the bandwidth to 10 Mb/s with a delay of 30 ms to the link connecting router1 and pc1:

# vlink -bw 10000000 -dly 30000 router1:pc1

Generate an error on one bit in a million:

# vlink -BER 1000000 router1:pc1

Set packet duplication to 20 # vlink -dup 20 router1:pc1

Modifying a link in a specific experiment (i.e. Experiment ID = i56ad1):

# vlink -dup 20 router1:pc1@i56ad1

To reset the link settings to the default values the -r flag is used:

# vlink -r router1:pc1@i56ad1