manual imunes

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UNIVERSITY OF ZAGREBFACULTY OF ELECTRICAL ENGINEERING AND COMPUTING

DEPARTMENT OF TELECOMMUNICATIONS

IMUNES

Users Guide

Zagreb, 2004.


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IMUNES: Users Guide


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Table of Contents

1. Introduction ........................................................................................................... 1

Overview ............................................................................................................ 1

IMUNES objects ................................................................................................ 1

Document organization ...................................................................................... 2

2. Creating and editing experiments ....................................................................... 3

Starting IMUNES............................................................................................... 3

Graphical User Interface .................................................................................... 3

Menu bar.................................................................................................... 4

File menu .......................................................................................... 4

Edit menu.......................................................................................... 5

View menu ........................................................................................ 5

Experiment........................................................................................ 5

Help................................................................................................... 5

Toolbox...................................................................................................... 5

Status bar ................................................................................................... 6Nodes.................................................................................................................. 6

Nodes manipulation................................................................................... 7

Adding new nodes............................................................................. 7

Selecting nodes ................................................................................. 7

Moving nodes ................................................................................... 8

Deleting nodes .................................................................................. 8

Configuring nodes ..................................................................................... 8

Attaching physical interfaces................................................................... 10

Interface manipulation .................................................................... 10

Assigning a physical interface ........................................................ 10

Links................................................................................................................. 11

Link manipulation ................................................................................... 11

Adding new links ............................................................................ 11

Deleting the link.............................................................................. 12

Configuring links ..................................................................................... 12

Example............................................................................................................ 13

3. Executing experiments........................................................................................ 16

Starting the simulation ..................................................................................... 16

Creation of nodes..................................................................................... 16

Creation of links ...................................................................................... 17

Configuring nodes ................................................................................... 17Simulation ........................................................................................................ 18

Example............................................................................................................ 20

Stopping the simulation.................................................................................... 23

Shutting down netgraph nodes ................................................................ 24

Shutting down vimages ........................................................................... 24

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Glossary ................................................................................................................... 26

A. Network topology configuration file ................................................................. 28

Description ....................................................................................................... 28

Nodes................................................................................................................ 28

type .......................................................................................................... 29

cpu ........................................................................................................... 29model ....................................................................................................... 29

network-config......................................................................................... 29

hostname name ............................................................................... 29

interface name................................................................................. 29

router protocol ................................................................................ 30

ip route networkIP gatewayIP......................................................... 30

iconcoords................................................................................................ 30

labelcoords............................................................................................... 31

interface-peer........................................................................................... 31

Links................................................................................................................. 32

duplicate .................................................................................................. 32

ber ............................................................................................................ 33

nodes........................................................................................................ 33

bandwidth ................................................................................................ 33

delay ........................................................................................................ 33

B. Getting IMUNES ................................................................................................ 34

C. Installing IMUNES ............................................................................................ 35

Prerequisites ..................................................................................................... 35

Download ......................................................................................................... 35

Install................................................................................................................ 35

D. Online resources ................................................................................................. 37

Bibliography ............................................................................................................ 38

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List of Figures

2-1. Graphical user interface layout ............................................................................ 4

2-2. Menu bar.............................................................................................................. 4

2-3. toolbox ................................................................................................................. 5

2-4. Status bar in the edit mode .................................................................................. 6

2-5. Status bar in the exec mode ................................................................................. 6

2-6. LAN switch configuration parameters................................................................. 8

2-7. Router configuration parameters ......................................................................... 9

2-8. Interface parameters........................................................................................... 10

2-9. Creating new link............................................................................................... 12

2-10. Link configuration parameters......................................................................... 12

2-11. Topology .......................................................................................................... 14

3-1. The status bar after transition from the edit to the exec mode ........................... 16

3-2. Error message .................................................................................................... 17

3-3. Statusbar during the creation of a link............................................................... 17

3-4. Status bar during the configuration of a node .................................................... 183-5. Toolbox during the simulation ........................................................................... 18

3-6. Consoles............................................................................................................. 19

3-7. Topology ............................................................................................................ 20

3-8. Routing table of the router0 ............................................................................... 21

3-9. Ping output......................................................................................................... 22

3-10. Traceroute from pc4 to host2........................................................................... 22

3-11. The result of stopping the simulation in a command line................................ 23

3-12. Imunes after hitting "terminate" ...................................................................... 24

A-1. Node configuration format................................................................................ 31

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Chapter 1. Introduction

Overview

IMUNES is an Integrated MUltiprotocol Network Emulator / Simulator. As

invaluable tools in networked and distributed systems research, network emulators

offer a viable alternative to live experimental / testbed networks. We are developing

a network emulation framework based on the FreeBSD operating system kernel

partitioned into multiple lightweight virtual nodes, which can be interconnected via

kernel-level links to form arbitrarily complex network topologies. The concept of

using virtual nodes inside a kernel for fast network emulation is not entirely new, yet

previously published work generally advocated the implementation of kernel-level

virtual nodes with capabilities limited to only certain simple functions, such as

passing of network frames from one queue to another based on a static precomputed

path. Our work is based on a thesis that virtual nodes, which could offer the identical

rich set of capabilities as the standard kernel does, can be implemented veryefficiently by reusing the existing OS kernel code. Our model therefore provides

each node with an independent replica of the entire standard network stack, thus

enabling highly realistic and detailed emulation of network routers. It also enables

each virtual node to run a private copy of any unmodified user-level application,

including routing protocol daemons, traffic generators, analyzers, or application

servers. Furthermore, in later development phases, we expect to enable each virtual

node to support multiple network protocols concurrently, such as both IPv4 and

IPv6, which would bring us a step closer to allowing for emulation of true

multiprotocol networked environments.

IMUNES objects

In IMUNES there are two basic construction units: nodes and links. Internally they

are presented as kernel structures, capable of preforming functions of the nodes and

the links that they simulate. By using this kernel structures different topologies can

be simulated.

Nodes are further classified into two groups:

link layer nodes

Nodes with no network layer functions, capable of operating with packets onlink layer level. Representatives of this group are LAN switch and physical

interface.

network layer nodes

Nodes with implemented IP network stack, capable of operating with packets

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Chapter 1. Introduction

on network layer level. Router, pc and host nodes fall into this category.

The use of nodes will be described in the Section called Nodes in Chapter 2.

Different types of links can also be simulated. This is accomplished by changing the

link parameters, as it will be described in the Section called Links in Chapter 2.

Document organization

In the Chapter 2 there is a detailed description of how to create the desired topology

in IMUNES. This includes how to start IMUNES, followed by the GUI description

and the use of IMUNES before starting simulation. In IMUNES there are two basic

building units, nodes and links. Different types of nodes, links and there parameters

allow the simulation to be more realistic. All this types and parameters are described

in this chapter. There will also be an example of creating and configuring a simple

topology.

Chapter 3 explaines what happens when simulation starts and how to use simulation

and stop simulation. Two operating modes of IMUNES are specified, edit and exec

mode. The way of accessing the console of a particular node will also be described.

During the simulation all kinds of different programs available on the hosting

machine can be started from any simulated network layer node. The parameters of

the simulated links and nodes can be dynamically changed during the simulation. At

the end there is an example.

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Chapter 2. Creating and editing experiments

Starting IMUNES

Installation of IMUNES is explained in Appendix C.

IMUNES usually runs under X11. The easiest way to start IMUNES is by writing

the following command in xterm command prompt:

# imunes

This will open an empty panel on which any desired topology can be drawn.

If the topology already exists (saved in IMUNES network topology configuration

file), by calling:

# imunes file_name.imn

the topology described in file file_name.imn will be displayed on the panel.Existing topology can be changed before starting the simulation. The simulation is

started and stopped using Experiment menu (Execute / Terminate).

If no GUI is available (no X11), or there is no need for it, IMUNES can be run from

console: Appendix A

# imunes -b file_name.imn

Topology, described in file_name.imn, will be created in kernel and accessible

through vimage functionality [5]. The simulation is automatically started and there

is no edit mode.

The simulation can be stopped from command line with:

# imunes -b

(all kernel structures will be destroyed, detached or removed)

Graphical User Interface

IMUNES comes with a simple Tcl/Tk based graphical user interface console ( Figure

2-1), which operates in two modes:

edit mode

exec mode

By starting IMUNES operating mode is set to edit mode.

Edit mode is the mode in which the topology can be modified by adding, deleting

and editing nodes or links. Exec mode is the mode in which the simulation runns.

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For further changes of the topology operating mode must be reset to edit mode

(Experiment -> Terimate).

Figure 2-1. Graphical user interface layout

The name of the current network configuration file can be seen in the windows title.

Default extension used for IMUNES network configuration files is imn. The menubar is right under the file name (Figure 2-2).

Menu bar

Figure 2-2. Menu bar

File menu

New - create a new fileOpen - open an existing fileSave - save new or opened file

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Save As - save new or opened file using a different namePrint- print current topology

Exit- exit IMUNES

New, Open, Save and Exit commands have shortcuts which are displayed after the

name of the command in the menu.

Edit menu

Undo - undo the previous action, also reachable through Ctrl + Z command.Redo - executes the action that was canceled, also reachable through Ctrl + Y command.

View menu

Submenu Show containing following items:

Show interface names - Show or hide interface names on the panelShow IP addresses - Show or hide IP addresses on the panelShow node labels - Show or hide node labels on the panelShow link labels - Show or hide link labels on the panel.

Experiment

Execute - Create virtual nodes and links and start the simulationTerminate - Stop simulation and destroy internal topology.

Help

About- Show copyright

Toolbox

On the left side there is a toolbox (figure 2-3).

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Figure 2-3. toolbox

Available tools are (in the order from top to bottom): select, delete, link, router,

LAN switch, host, pc and physical interface. Router, host and pc represent network

layer nodes while LAN switch and physical interface represent link layer nodes.They will all be explained in the Section called Nodes.

Status bar

On the bottom there is a status bar, divided into four fields. The first indicates

current configuration of the object under the mouse pointer. It is used in edit and

exec modes. During the transition from the edit to the exec mode and vice versa it

also indicates actions being performed in the background. The second and the third

field are used only in the exec mode for indication of the resources being used by

IMUNES. The last field shows the current operating mode. The following figuresrepresent status bar in the edit mode (Figure 2-4) and the exec mode (Figure 2-5).

Figure 2-4. Status bar in the edit mode

Figure 2-5. Status bar in the exec mode

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Nodes

In IMUNES there are two groups of nodes:

network layer nodes

link layer nodes

There are three different network layer node types: router, host and pc.

Routeris a node performing a routing function and running some routing

daemon.

Hostis using only static routing and has some services started by default. They

are portmap, inetd and netserver.

PC is also using only static routes. No additional services are started during the

configuration.

There are two different link layer node types: LAN switch and physical interface

LAN switch has no IP address. Any number of other types of nodes can be

connected to it. Two LAN switches can not be connected directly.

Physical interface represents real physical interface used for communication of

the simulated network with external network.

Nodes manipulation

Adding new nodes

New nodes can be added to the panel simply by choosing the apropriate type of a

node in the toolbox and clicking on the desired place on the panel. Every subsequent

node can be added simply by clicking on the desired place on the panel. When all

nodes are placed it is recommended to change the active tool to "select".

Selecting nodes

For selecting nodes on the panel active tool must be set to select tool. One node can

be selected simple by clicking on it. Pressing the left mouse button on one point on

the panel and releasing it on some other point will select all the nodes inside

rectangle visable during this process. All the selected nodes have bordes aroud them.

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Moving nodes

Existing nodes can be rearranged using the select tool. Moving is accomplished by

dragging the selected nodes to the new position and dropping it there (drag&drop

method). All links that are connected to selected nodes are also moved. Node labels

can also be rearranged using the same drag&drop method.

Deleting nodes

Nodes can be deleted using the delete tool. Clicking on the node while the delete

tool is active will delete that node. When deleting a node all links associated with

that node will also be deleted. Deleting two or more nodes at the same time is

accomplished by selecting the nodes and clicking on either one of them with the

active tool set to the delete tool.

Configuring nodes

Each node has a set of parameters associated with it. Parameters of a node can be

viewed or changed by double clicking on the node. Figure 2-6 shows parameters of

a LAN switch.

The first parameter is the Node name, and every node has it. The name of the node is

displayed on the label next to the node. It is not the name in DNS, so it can not be

used for communication between nodes. The same name can be used for more than

one node.

The name of the node is not a node identifier. The node identifier is in the form of

na, where a is a unique numerical value. This identifier is written in the network

topology configuration file (after the key word node).

Every node, if it is linked to some other node, has interfaces.

For each LAN switch interface the type of a queue can be selected. Available types

are: FIFO, DRR, and WFQ. It is also possible to change the packet dropping policy

from droptail to drophead. Another parameter available is a maximal queue length,

set to 50 packages by default. Parameters of a LAN switch as well as the different

values for the type of a queue, the dropping policy and the maximal queue size can

be seen on the Figure 2-6.

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Figure 2-6. LAN switch configuration parameters

Interfaces of all the other nodes have some additional parameters. They have the

possibility of shutting down the interface or bringing it up. Every interface of a

router, PC or host also has an IP address. Allowed format for IP addresses is:

a.b.c.d/m, where m is the number of the bits masked for determining the subnet.

MTU can also be defined for every interface of a router, host or PC.

Static routes can be written for every network layer node. The format for writing

routes is: a.b.c.d/m gatewayIP. Routers have the option for using quagga [3] or static

routing model. Support for XORP [4] is under development. Currently default

dynamic routing protocol is RIPv2, but quagga [3] has the support for other routing

protocols, such as OSPF and BGP. Router configuration parameters are shown on

the Figure 2-7.

Figure 2-7. Router configuration parameters

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Every PC, router or host has additional parameters for virtual image [2] that will be

created on its place in the kernel. The first parameter determinates the minimum

CPU load, the second maximum CPU load, and weight is the parameter that shows

how the virtual image will compete for CPU time. For more information on this

parameters check [5].

Attaching physical interfaces

Physical interface tool in the toolbox has the purpose of connecting a real (physical,

external) interface to the simulated node. Through this tool the simulated network

can communicate with an external network.

Interface manipulation

Interface can be manipulated in the following ways:

Adding a new physical interface

It is done in the same way as for any other node. Select the physical interface

tool and click on the desired place on the panel. New physical interface gets a

label UNASSIGNED. This label must be changed before the simulation can

be started (see "Assigning an interface")

Deleting a physical interface

Deleting the physical interface is done by selecting delete tool and clicking

over the interface that is to be deleted.

Connecting the physical interface

Physical interface can be connected to a router or a LAN switch by using

links. Interface can not be connected more than once. The connection can be

broken by deleting the link that is connecting it to the node.

Assigning a physical interface

As explained earlier newly created interface is considered unassigned. The process

of assigning an interface is similar to changing parameters of a node or a link. By

double clicking on the interface, the dialog box (Figure 2-8) appears.

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Figure 2-8. Interface parameters

The name of the interface must be changed into the name of an existing physical

interface on the machine where the simulation is run (for example: lnc0). For every

existing physical interface 4096 different VLAN identifiers can be used. By using

different VLAN identifiers it is possible to connect one physical interface to more

than one node.

It is not allowed to have:

more than one interface associated to the same physical interface and the same

VLAN identifier,

interface that is not assigned,

interface that is assigned to a nonexistent physical interface.

The other parameters of the physical interface are configured on the corresponding

interface of the node to which the physical interface is connected. When physical

interface is assigned to a router the queue type ( FIFO, DRR, and WFQ), the packet

dropping policy (drophead, droptail) and the queue length are not available on that

interface.

Links

Every node can be connected to almost any other node by using links. Already

connected nodes can not be connected again (only one link between two nodes can

be made).

Link manipulationLinks can be created or deleted. The first node and the second node of a link can not

be changed. Deleting any node, that the link connects, will also delete the link.

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Adding new links

For connecting two nodes (adding a new link), the link tool must be selected.

Pressing the left mouse button on the first node and releasing it on the second node

will create link between those two nodes. The Figure 2-9 shows link creation. If

mouse button is released with no node under it, new link will not be created. The

link between two LAN switches is not allowed. After all desired links are added, itis recommended to change the active tool to select tool.

Figure 2-9. Creating new link

Deleting the link

Deleting links is similar to deleting nodes. The delete tool must be selected.

Clicking on the link that is to be deleted, removes it from the topology.

Configuring links

Different types of links can be simulated by changing the parameters of the link.

These parameters are accessed by double clicking on the link. On the Figure 2-10

these parameters can be seen.

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Figure 2-10. Link configuration parameters

Bandwidth

It is measured in the number of bits per second (bps). By changing this

parameter we can simulate slow or fast links, and change transmition delay for

packages. The allowed values are between 100 and 109.

Delay

It is used for the simulation of a propagation delay which depends on the

length of a link and the link bandwidth. The delay is measured in us. The

allowed values are in between 0 to 107.

BER

It represents the probability of a bit error rate. This probability is equal to 1/N,

where N is the integer value entered in the BER field. Maximum 1012. If there

is no BER specified, or the value ofBER is set to 0, then it is assumed that the

link is transmitting without error .

Duplicate

It represents the probability of occurrence of duplicate packages on the link. It

is measured in %. The allowed values are between 0 and 50.

Link that is used for the connection of a physical interface with a node is considered

ideal so it has no parameters, and thus can not be configured.

ExampleIn this section the procedure of creating a simple topology will be demonstrated.

The same topology will be used in the next section.

This topology will consists of two routers, one LAN switch, two PCs, one host and

one physical interface connected to a local network.

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The described topology is created using following steps:

1. Select the router node tool and click on the panel on two different places. This

will create two new routers.

2. Select the host node tool and click on the empty space on the panel.

3. Select the LAN switch node tool and click on the panel, this will create a new

LAN switch on the panel.

4. Select the PC node tool from the toolbox and click on the panel on two

different places.

5. Select the physical interface tool and click on the panel. At this time all nodes

will be added to the panel.

6. Choose select tool from the toolbox and place (move) the created objects to the

desired places (as in the Figure 2-11).

7. Select the link tool and connect objects on the panel in the way they are

connected in the Figure 2-11.

When all nodes and links are added, it is the time to configure the topology.

The first thing to do is to assign the physical interface node to a real physical

interface. This is accomplished by double clicking on the physical interface node

and changing its name parameter to an existing physical interface name (run ifconfig

for viewing the list of existing interfaces). On Figure 2-11 the interface node is

assigned to the lnc0 physical interface.

Set the delay of the link connecting pc4 and lanswitch3 to 10ms:

1. Double click on the link connecting pc4 and lanswitch3.

2. Enter 10000 in the field for delay.

3. Select Apply.

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Figure 2-11. Topology

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Chapter 3. Executing experiments

Starting the simulation

Simulation can be started when the desired topology is generated. Simulation starts

by choosing Experiment -> Execute command. The operating mode is switched to

the exec mode.

During the translation from the edit mode to the exec mode all necessary objects are

created in the kernel.

In the exec mode no additional topology can be drawn.

Another way to start the simulation is by using -b option and the network topology

configuration file when starting IMUNES from a command line (as described in the

Section called Starting IMUNES in Chapter 2). If the simulation is started this way

then there is no GUI.

This is the list of the things that happen when starting the simulation:

1. Clean up - IMUNES checks if there are some objects left from the previous

simulation and cleans them up.

2. Creation of nodes - IMUNES creates simulated nodes and physical interfaces.

It is explained in more details in the Section called Creation of nodes.

3. Creation of links - links and interfaces are created and configured in this phase

(see the the Section called Creation of links).

4. Configuration of nodes - nodes are configured (see the the Section called

Configuring nodes).

5. After the configuration of all nodes and links has been finished the status bar

indicates how long it took to make all necessary objects in the kernel.

Figure 3-1. The status bar after transition from the edit to the exec mode

This process is the same for starting IMUNES without GUI and all status bar

comments are sequentially displayed on a console.

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Creation of nodes

There are no differences between a host, PC and router in this stage. Every one of

them is treated as an exact replica of hosting FreeBSD system with no active

processes. This virtual images are created using vimage functionality [5].

Virtual images are created only for the network layer nodes.

The physical interfaces are brought up. If the physical interface name in IMUNES

does not respond to the real physical interface name, or there are more then one

interfaces with the same name and the vlan identifier, simulation can not be started.

In that case the message like the one on the Figure 3-2 is displayed.

Figure 3-2. Error message

During the creation of nodes there is an appropriate message displayed in the status

bar.

Creation of links

Creation of links starts internally with the creation of interfaces in every node.

Different types of interfaces are added, depending on the type of connection (forexample: between a LAN switch and any other node, Ethernet type of the interface

is created). When all the interfaces are created, or added (in the case of physical

interface) to the node, links are created. The parameters of the links are used to

configure links. In this step also the configuration of all interfaces is made. This

means the packet dropping policy is enforced, the queue length and the type of a

queue is set.

Figure 3-3. Statusbar during the creation of a link

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Configuring nodes

For every host, router and PC the parameters for the CPU (min, max and weight) are

enforced and the loop back interface is created. MTU is also set.

In this step difference between a PC, router and host is made:

Router- the routing model and the routing protocol are set. The kernel variable

net.inet.ip.forwarding is set to 1, so the forwarding of packages is enabled.

Host- the programs portmap, inetd and netserver are started. Static routes are

set.

PC - Static routes are set.

The status bar at this time is similar to the one on the Figure 3-4.

Figure 3-4. Status bar during the configuration of a node

Simulation

Once the simulation has started, no additional topology can be generated. Only the

select tool from toolbox is available for rearranging the topology (nodes can be

moved in the way described in the Section called Moving nodes in Chapter 2).

Nodes and links can not be added or deleted. The look of the toolbox during thesimulation is presented on the Figure 3-5.

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Figure 3-5. Toolbox during the simulation

On the previous figure, another thing can be noticed. In the status bar second and

third fields are filled. The second field represents the current CPU load, and must be

in some reasonable limits. In the third field the precentage of used mbufers and

clousters is presented. If this number reaches 100% then kernel variables

kern.ipc.nmbclusters and kern.ipc.nmbufs in the /boot/loader.conf file must be set to

larger values and the system should reboot for changes to make an effect.

The parameters of nodes and links can be changed. This is accomplished by double

clicking on the node or the link, and editing the dialog box that appears. The

parameters of the nodes are described in the Section called Configuring nodes in

Chapter 2, and the parameters of the links in the Section called Configuring links in

Chapter 2.

Execpt for limitations on options available during the edit mode, in the exec mode a

new option is available. By clicking the right mouse button on a network layer node

the console opens (On the Figure 3-6 open consoles for router0, host2 and PC4 can

be seen). For a router this console is the standard vtysh shell and for a host or PC the

csh shell. More than one console per node can be open at the same time.

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Figure 3-6. Consoles

By using the csh shell new processes can be started on each host or PC. The

available programs and processes are the same as for the FreeBSD system that hosts

IMUNES.

Console for each node can be also accessed if IMUNES is started without GUI with

command:

# vimage na

Where na is the unique identifier for a node. The value of the node identifier can be

found in the network topology configuration file, which is formatted as described in

Appendix A. By writing exit the control over the console is returned.

Example

In this section the topology from the Section called Example in Chapter 2 will be

simulated.

This topology is presented on the Figure 3-7.

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Figure 3-7. Topology

Simulation starts by hitting Experiment -> Execute. Now, when all necessary

kernel objects are created this topology can be used.

The routing table of router0 can be viewed by opening a vtysh console on router0

(right click on router0 icon), and typing the following command:

router0> show ip route

The output is presented on the Figure 3-8

Figure 3-8. Routing table of the router0

The output shows that there are three directly connected networks, the network

10.0.0.0/24 through the interface eth0, the network 10.0.1.0/24 through the interface

ser0 and the loopback network (127.0.0.0/8) connected through the loopback

interface lo0.

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There are also two routes obtained with RIP routing protocol. From this routes it can

be seen that the network 10.0.2.0/24 and the network 10.0.3.0/24 are reachable

through the router interface ser0, using the gateway 10.0.1.2.

Ping is the standard program used for testing network connectivity. Here it will be

used to show that simulated nodes can be reached from the node pc4:

# ping 10.0.0.2

The output is presented on the Figure 3-9

Figure 3-9. Ping output

As presented on the Figure 3-9 from 10 packets transmitted, all 10 was received, and

none was lost. The average RTT is 26.153, which is very close to the expected RTTof 25.578ms for the given propagation and transmition delay.

The last program used to demonstrate the network connectivity is treaceroute. This

program shows the most probable hops that a packet has made on his way to the

destination. The use of this program is simple, just writing:

# traceroute ipaddr

in the console results in the list of hopes and three RTT for every hop.

To use treceroute from pc4 to host2 a console must be open on pc4. From the Figure

3-7 it can be seen that the only path from pc4 to host2 is through lanswitch3, router1

and router0. Writing:

# traceroute 10.0.0.2

results in displaying the following list. The LAN switch has no network layer so it

wont be displayed in the list of hops.

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Figure 3-10. Traceroute from pc4 to host2

Stopping the simulation

Simulation that was started with a GUI stops by choosing Experiment ->

Terminate command. The operating mode is switched back to the edit mode.

During the translation from the exec to the edit mode all kernel objects, used by

simulation, are destroyed.

Stopping the simulation that was started from a command line (by using -b option

and a network topology configuration file when calling IMUNES) is accomplished

by calling imunes with -b option (without any other arguments).

# imunes -b

Figure 3-11. The result of stopping the simulation in a command line

The process of stopping the simulation can be divided into two basic actions:

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Shutting down netgraph nodes

Shutting down vimages

Shutting down netgraph nodesEvery link, interface (virtual or physical) or LAN switch represents one netgraph

node. All of the netgraph nodes are being shut down at this time. The message,

displayed in the status bar or on the console, uses only netgraph node and its

internal name for informing of links, interfaces and LAN switches detachment,

destruction or reassignment.

The format for the netgraph node name of the link is na-nb, where a and b are

identifiers of the nodes that are connected with the link.

The format for the netgraph node name of the interfaces is IfcName@nb. IfcName is

the name of the interface and b is the identifier of the node to which this interface isattached.

LAN switch netgraph node name is in the form of n a, where a is the identifier of the

LAN switch node.

Shutting down vimages

Every PC, host or router is represented in the kernel with a corresponding vimage

[2]. The process of shutting down vimages is divided into following steps:

Killing all processes attached to any vimage.

Deleting all temporary files created by the simulation.

Deleting every vimage.

Restoring original files like /etc/resolv.conf.

After all nodes, links and interfaces are shut down the status bar indicates how long

it took for imunes to stop the simulation (Figure 3-12).

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Figure 3-12. Imunes after hitting "terminate"

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Glossary

Bit Error Rate

Represents the probability of occurring an error on one bit during the

transmition.

Border Gateway Protocol

An inter-Autonomous System routing protocol. Its primary function is to

exchange the network reachability information with other BGP systems. Those

information are sufficient for constructing a graph of the autonomous system

connectivity.

See Also: Routing Information Protocol, Open Shortest Path First.

Deficit Round Robin

A modified weighted round robin scheduling discipline. It can handle packets

of a variable size without knowing their mean size. It serves packets at the head

of every nonempty queue which deficit counter is greater than the packets size.

If its lower, then the deficit counter is increased by some given value called

quantum. Deficit counter is decreased by the size of packets being served.

See Also: Weighted Fair Queuing.

Explicit Congestion Notification

Addition to the active queuing management. Instead of dropping the packet, a

notification is being sent to the sender. The source responds like the packet is

being dropped.

See Also: Random Early Detection.

First In First Out

One of the queuing algorithms. The packet that came first is the one that is

transmitted first.

See Also: Weighted Fair Queuing.

Head dropping

Static queue management algorithm. The packages are dropped from the front

of the queue when the queue overflows.

See Also: Tail dropping.

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Maximum Transmission Unit

The maximum number of bytes of data that can be transmitted through the link

without performing IP fragmentation.

Open Shortest Path First

Routing protocol. The packet is routed thorough the path with the minimum

cost (shortest path).

See Also: Routing Information Protocol, Border Gateway Protocol.

Random Early Detection

Active queue management algorithm. The packages are dropped with some

probability before the queue overflows. The probability of packet dropping is

calculated on the time-averaged queue length.

See Also: Explicit Congestion Notification.

Routing Information Protocol

Routing protocol. The packet is routed thorough the path with the minimum

number of hops.

See Also: Open Shortest Path First.

Tail dropping

Static queue management algorithm. The packages are dropped from the tail of

the queue when the queue overflows.

See Also: Head dropping.

Weighted Fair Queuing

One of the fair queuing algorithms. The packet is classified and assigned to one

queue. The queue is served in a weighted round robin manner.

See Also: Deficit Round Robin, First In First Out.

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Appendix A. Network topology configuration file

Description

The IMUNES network topology configuration file consists of a list of nodes and a

list of links. This file can be created in two ways:

using IMUNES GUI,

using text editor.

When using the IMUNES GUI, the topology displayed and configured can be saved

in a new or an existing network topology configuration file, under the desired name.

On the other hand, if no GUI is available it can be wrote in any textual editor.

The main format of network topology configuration file contains sections concerningnodes and sections concerning links. Written in the terms of regular expesions:

file := [nodes]*[linkes]*

Nodes

Nodes are entered by using a node identifier. After the node identifier, there is an

open bracket that is closed after the last entry concerning that node.

Inside the brackets following things can be found in described order:

nodes :=

node node_identifier {

type host|router|PC|lanswitch|rj45

[cpu {{ min min_value } { max max_value } { weight weight_value }}

[model quagga]

network-config {

[hostname] name

[interface ifc_name

[drophead]

[shutdown]

[fair-queue|drr-queue]

[ip address a.b.c.d/m]

[queue-len n]

[mtu n]]+

[router protocol

-- CISCO style cofiguration of routers]

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[ip route networkIP gatewayIP]

[iconcoords {a b}

labelcoords {a b}]

[interface-peer {ifc node}]*

}

type

type host | router | PC | lanswitch | rj45

This parameter is required. Allowed values are: host, PC, router, lanswitch or

rj45.

cpu

cpu := cpu {{min min_value} {max max_value} {weight

weight_value}}

This parameter is optional. It defines minimum and maximum CPU load, and the

weight.

model

This parameter is optional. The currently allowed value is quagga

network-config

This parameter is required. It represents CISCO style [7] configuration of a network

. It contains some sections (listed below), that can be divided by "!".

hostname name

Defines the name of the host. It is optional.

interface name

Defines the name of the interface, and interface configuration parameters. They are

the following:

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drophead

Dropps packets from the front of the queue. If nothing specified, the droptail

packet policy is assumed.

shutdown

On start of the simulation the interface will be shutdown. If nothing specified,

it is assumed the interface is up.

fair-queue

The interface queuing algorithm is set to the Weighted Fair Queuing. This

option can not be used together with drr-queue option. If no fair-queue

and no drr-queue option is specified, fifo queuing algorithm is assumed.

drr-queue

The interface queuing algorithm is set to the Deficit Round Robin. This option

can not be used together with fair-queue option. If no fair-queue or nodrr-queue option is specified, the First In First Out queuing algorithm is

assumed.

ip address a.b.c.d/m

The IP address is set to a.b.c.d and subnet mask is set to m bits.

queue-len n

The queue length is set to the numeric value n.

mtu n

The value ofMaximum Transmission Unitis set to the numeric value n.

router protocol

The routing protocol is set to protocol. Additional parameters are the same as for

CISCO [7] routers. This parameter is optional and usually set only for a router type

of nodes.

ip route networkIP gatewayIP

Additional static ip routes. This parameter is optional and usually set for a host or a

PC types of nodes. networkIP is in the format a.b.c.d/m, and gatewayIP in the

format a.b.c.d.

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iconcoords

This parameter is optional for simulations started without the GUI and required for

simulations with the GUI. It saves the position of the node icon on the panel. The

format or this option is the following:

iconcoords {a b}

a and b are numbers in the format n.0, where n is a numerical value representing the

number of pixels from the left top corner of the panel in the GUI of IMUNES ( a -

width, b - height).

labelcoords

This parameter is optional for simulations started without the GUI and required for

simulations with the GUI. It saves the position of the node label on the panel. The

format of this option is the following:

labelcoords {a b}

a and b are numbers in the format n.0, where n is a numerical value representing the

number of pixels from the left top corner of the panel in the GUI of IMUNES ( a -

width, b - height).

interface-peer

This parameter is used for every interface of the node. The format of this option is

the following:

interface-peer {ifc node}

ifc is the name of the interface and node is the name of the peer node (the node is

connected to the interface).

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Figure A-1. Node configuration format

Links

Links are entered by using the link keyword followed by the link unique identifier

in the form of la, where a is a numerical value. The parameters of the link (except

for the link identifier) are listed together in the section that starts with an open

bracket, and ends with close bracket. The parameters of the links are the following:

links :=

link link_identifier {

[duplicate n]

[ber n]

nodes {na nb}

bandwidth n

[delay n]

}

duplicate

This parameter determents the packet duplicate percentage as a numerical value. It is

entered in the following format:

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duplicate n

Where n is the percentage of the duplicated packets on the network. This parameter

is optional.

ber

Ber represents the Bit Error Rate.It is entered in the following format:

ber n

Where probability of the Bit Error Rate is calculated as 1/n. This parameter is

optional.

nodes

This parameter consists of two node identifiers, representing the end nodes for the

link. The format of this parameter is the following:

nodes {na nb}

The na and nb stand for the identifiers of the end nodes. This parameter is required.

bandwidth

This parameter represents the bandwidth of the simulated link in the bits per second

unit. The format is the following:

bandwidth n

Where n is a numerical value of the bandwidth. This parameter is required.

delay

This parameter represents the delay on the link. It is in the following format:

delay n

Where n is the delay measured in us. This parameter is optional.

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Appendix B. Getting IMUNES

There are two alernatives for getting IMUNES:

Using bootable CD,

Installing on FreeBSD 4.10-RELEASE (-STABLE most probably wont do!).

The process of installing IMUNES is described in Appendix C.

Using bootable CD should be straightforward, and most importantly it doesnt need

and wont touch anything on your disk drives.

Just download ISO image of bootable CD:

limunes-latest.iso.gz1

Burn this image and boot the system from CD.

From the menu select IMUNES.

This will automaticaly start X11 and IMUNES with GUI. There still might be a few

problems in correctly autoconfiguring X11, so be warned that you may need to

spend some extra time to get it running. You can select Configure X11 from

menu, and select one of the presented options (configuration using xf86cfg, comand

line xf86config, repeat autoconfiguration or insert mode lines in XF86Config). If

this dosnt help there is a shell for manual configuration.

After using IMUNES reboot the system and remember to remove the bootable CD

from your CD-ROM drive.

Notes

1. http://www.tel.fer.hr/imunes/dl/limunes-20041130.iso.gz

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Appendix C. Installing IMUNES

IMUNES runns only under FreeBSD 4.10-RELEASE (-STABILE most probably

wont do!).

If you dont have FreeBSD 4.10-R installed, for all informations about installing it,

visit www.FreeBSD.org [8]

Prerequisites

The following standard FreeBSD packages are prerequisites for running IMUNES:

tcl-8.4.6,1

tk-8.4.6,1

expect-5.38.0_3

quagga-0.96.4_5

netperf-2.2.4

They can be installed by using packages or ports ([9] - for more informations on

installation using packages or ports).

Download

After ensuring all the prerequisites are installed download the files bellow.

IMUNES uses patched FreeBSD 4.10-R kernel, so in the next step you will have to

patch and rebuild krenel. Download the latest IMUNES patch to /usr/src:

4.10-R-latest.diff.gz1

And to any other folder the following files:

vimage-20040209.tgz 2

ng_pipe-20041024.tgz 3

imunes-20040916.tgz 4

Install

The downloaded kernel patch provides the ability to simultaneously maintain

multiple network stack instances within a single running kernel. For moreinformations check [10].

Type on the console:

# cd /usr/src

# mkdir sys/modules/if_ve

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Appendix C. Installing IMUNES

# gzcat 4.10-R-20041122.diff.gz | patch

Rebuild the kernel in the usual way using your own kernel configuration file or using

LIMUNES kernel configuration file. If you want to use your own kernel

configuration file remove anything related to INET6 or IPSEC. Using LIMUNES

kernel configuration file some devices may not work properly and you may add

some additional support as long as it is not related to INET6 or IPSEC [ 11].

After building and installing the kernel, reboot and go to the folder containing

vimage-20040209.tgz and install vimage:

# tar -xzvf vimage-20040209.tgz

# cd vimage

# make; make install

Install ng_pipe-20041024.tgz:

# tar -xzvf ng_pipe-20041024.tgz

# cd ng_pipe# make; make install

Install imunes-20040916.tgz

# tar -xzvf imunes-20040916.tgz

# cd imunes

# ./install.sh

Notes

1. http://www.tel.fer.hr/imunes/dl/4.10-R-latest.diff.gz2. http://www.tel.fer.hr/imunes/dl/vimage-20040209.tgz

3. http://www.tel.fer.hr/imunes/dl/ng_pipe-20041024.tgz

4. http://www.tel.fer.hr/imunes/dl/imunes-20040916.tgz

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Appendix D. Online resources

For now there is only one mailing list: [email protected]. For subscription visit

http://mail.tel.fer.hr/mailman/listinfo/imunes

Notes1. mailto:[email protected]

2. http://mail.tel.fer.hr/mailman/listinfo/imunes

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Bibliography

[1] Operating System Support for Integrated Network Emulation in IMUNES 1,

Marko Zec, Miljenko Mikuc, Proceedings of the 1st Workshop on Operating

System and Architectural Support for the on demand IT InfraStructure /

ASPLOS-XI, Boston, October 2004.

[2] Implementing a Clonable Network Stack in the FreeBSD Kernel 2, Marko Zec,

Proceedings of the 2003. USENIX Annual Technical Conference, San

Antonio, Texas, June 2003.

[3] Quagga3 - routing model .

[4] XORP4 - The eXtensible Open Router Platform at ICSI5.

[5] vimage functionality man pages.

[6] ng_pipe functionality man pages .

[7] CISCO6.

[8] FreeBSD site7.

[9] FreeBSD documentation of installation using packages or ports8.

[10] Simultaneously mantaining multiple network stack instances9.

[11] FreeBSD documentation on building kernel10.

Notes

1. http://tel.fer.hr/zec/papers/zec-mikuc-04.pdf

2. http://fer.hr/zec/papers/zec-03.pdf

3. http://www.quagga.net

4. http://www.xorp.org

5. http://www.icsi.berkeley.edu

6. http://www.cisco.com

7. http://www.FreeBSD.org

8. http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/ports.html

9. http://www.tel.fer.hr/zec/vimage/index.html

10. http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig-

building html

manual imunes

Documents