Remote Laboratory for Computer Networks

Ladislav Balik, Josef Horalek, Vladimir Sobeslav and Ondrej Hornig

Faculty of Informatics and Management, University of Hradec Králové,

Rokitanského 62, 50003, Hradec Králové, Czech Republic

Keywords: Education, Remote Lab, Cisco Certified Network Professional, Access to Hardware, Network Architecture

and Design.

Abstract: The article introduces the reasons for realisation of the remote laboratory of computer networks which

originate from the comparisons of the alternatives of working with the specialised networking hardware.

These use the principle of virtualisation or simulation of such devices as an alternative for obtaining

competencies from the area of computer networks. Due to this reason, this article discusses other technical

solutions and the analysis of usability of such solutions is conducted. For a maximal efficiency of the

networking hardware utilization in laboratories it is necessary to make it fully available for students which

is the 24/7 regime. This option can be executed using secure technologies and protocols for distant

accessing of laboratory hardware. This solution, which is based on using console controllers and single

utility interface, is introduced and described in detail in the following paragraphs. Moreover, from the

analysis of the pilot operation of remote access to the laboratory equipment of the networking laboratory,

suggestions for improvement of the current solution and its usage in fully working condition – access to a

greater number of students in unlimited regime – can be obtained.

1 INTRODUCTION

As the reason of the education strategy of the

Informatics and Management Faculty of the Hradec

Kralove University, which is particularly focused on

the practical usage of learning, the Cisco

Networking Academy programme was incorporated

in bachelor courses called Applied Informatics and

Information Management in 2007. Four basic

modules Introduction to Networks, Routing and

Switching Essentials, Scaling Networks and

Connecting Networks are included in the

educational process. These modules form the basic

elements of the so called Cisco Certified Network

Associate (CCNA). In order to enable the teaching

of these subjects, it is necessary to have a

professionally equipped computer network

laboratory with elements, such as Cisco 2801 and

2911 routers and Cisco Catalyst 2960 and 3560

switches. This equipment is essential for execution

of above mentioned courses. Students can use these

elements when working on laboratory tasks within

the practical exercises in subjects of Computer

Networks I to IV.

This set of basic courses is followed by more

advanced and complex subjects, which go into a

much greater detail in many related areas and are

called collectively Cisco Certified Network

Professional (CCNP). This course contains (Odom,

2010) Cisco CCNP ROUTE: Implementing IP

Routing, (Hucaby, 2010) Cisco CCNP SWITCH:

Implementing IP Switching and (Wallace, 2010)

Cisco CCNP TSHOOT: Maintaining and

Troubleshooting IP Networks. These courses are

very specialised and difficult for lecturers and

students that they cannot be incorporated into a

standard education on a bachelor or magister level

and are therefore taught in specialized lectures once

per two years. The profound knowledge of

theoretical concepts of such matters is required, as

well as practical skills of students who need to be

able to solve within timely laboratory exercises

(Browning and Tafa, 2011) the specific

configurations and problems on professional

network elements that are often used in a job

environment. The common solution of one task

would take one student even more than 4 hours

which means that even with sufficient hardware

equipment of the laboratory at the faculty, it is often

difficult to compensate students the lack of time for

solution of such tasks. This is either due to the lack

Balik L., Horalek J., Sobeslav V. and Hornig O..

Remote Laboratory for Computer Networks.

DOI: 10.5220/0005113600280035

In Proceedings of the 5th International Conference on Data Communication Networking (DCNET-2014), pages 28-35

ISBN: 978-989-758-042-0

 2014 SCITEPRESS (Science and Technology Publications, Lda.)

of time that the student has or lack of the reserved

time for access of the laboratory.

Especially the above mentioned restrictions of

physical access to the specialised equipment was one

of the main reasons for the suggestion to the

execution of remote access to the individual

elements and in this way enable the solution of

assigned tasks independently of the physical

presence of the student in the laboratory. The

implementation of this distant access for students

would enable the teaching of above mentioned

courses more frequently than once per two year and

also it would enable distant education of such

courses using e-learning tools. This solution also

uses individual physical topologies in terms of the

taught course where the specification is based on the

specialised software configurations of individual

elements and not on the physical connection. This

represents the solution to problems in real life on the

basis of hierarchical network design model.

2 USE OF REMOTE

LABORATORY FOR

EDUCATION

There are many scientific research and educational

institutions which are engaged in the suggestion and

solution of distant laboratories, not only in the Czech

Republic. The common view on the issue of using

distant laboratories and their usage for educational

purposes is presented by Barrios, A (2013) who

namely introduces the structure and accesses of the

distant laboratories systems and their

interconnection with Learning Management

Systems. The specific solution for using PLC

devices is suggested in the article of Chen, X and

Gao, H (2012) which also focuses on specifications

of distant access to hardware tools of PLC systems.

Similar characteristics should be taken into account

when finding the solution for access to the computer

network laboratories which is aimed at enabling the

access to the built physical network topology in the

area of Cisco Certified Network Professional

certification to students.

2.1 Secondary Access

The teaching of computer networks at the

universities requires, even for the basic

understanding of the given topic, a complex study

access including the opportunities for checking the

obtained theoretical knowledge on practical

examples. In this way, the student’s competencies

can be expanded. The learning of specifications and

protocols cannot replace the practical part of the

subject which is the previously mentioned

configuration of real devices in a tangible topology,

ideally with a maximum of real data traffic.

As Bodnarova, A. (2010) presents, in the case

when there are no suitable specialised hardware

tools for individual teaching, for example in the

home setting, it is possible to use simulation or

virtual tools. One of the simulation tools is for

example Cisco Packet Tracer by Cisco Systems

(2104), a proprietary simulation tool for students of

the Cisco Networking Academy. The disadvantage

of such solution is how abstract the real behaviour of

the system is. This can further result in

misinterpretation of results. However, it is simply to

develop such tools and run them even on basic

computer systems due to the fact that they can be

used by beginners.

The virtual tools can closer simulate the

behaviour of the network device system. However,

there are serious problems with licencing of the

active elements of operation systems and with high

power overload which can generate these devices.

One of such devices is for example a freely available

virtual tool GNS3 by GNS3 (2014) or IOU as

described by Route Reflector (2014).

If the mentioned disadvantages of both

approaches should be avoided, it is necessary to

compromise and work on real devices which are the

only ones that can provide authentic response and

realistic (predictable) behaviour. The local

connection to the device is usually not the main

problem as it can be accessed by standardised

protocols, such as telnet or SSH.

However, when not working from the home

environment or university environment, but during

the home studying, it can be difficult to optimally

allocate hardware resources in a way to serve the

highest number of students without collisions. Our

introduced solution was able to solve this problem to

a certain extent and the way in which it was done is

presented below.

2.2 Remote Lab Concepts

The purpose of the introduced solution was to create

a system for distant access to the specialised

network hardware within the previously built

physical topology. The philosophy of the pilot

project originates from the sample laboratory

exercises of the course (Wallace, 2010) CCNP

TSHOOT which are used for practical verification of

RemoteLaboratoryforComputerNetworks

obtained competencies in the area of advanced

computer networks.

The specification of these tasks is that they are

executed in one physical topology which is

represented in Fig. 1 and is used for various types of

configurations and detection of hidden problems in

realised network. Three routers Cisco 2801, Cisco

2911, two L3 distribution layer switches Cisco

Catalyst 3560 and one access switch Cisco Catalyst

2960 are used here.

A student can request a reservation for specific

time for his/hers training and the correction of

his/hers knowledge in practical tasks where he/she

can choose the particular topic whose pre-

configurations are then automatically recorded on

the single network elements. Three identical logical

topologies which are mutually interconnected (as is

described below) are available in the pilot operation.

A student can, according to the difficulty of the

chosen task, work on one to three topologies

simultaneously or up to three students can work

concurrently or independently of each other. In the

same time, a student has the choice of ten different

laboratory tasks which cover the most important

topics of the above mentioned course.

R2 R3

DLS1L3 DLS2L3

ALS1L2

Figure 1: The basic scheme of physical labs topology.

2.3 Remote Lab Structure

The system of the remote lab can be divided into

three basic block components, as is shown on the

Fig. 2. The first basic component is the virtual server

which takes care of the maintenance of the actual

remote lab and provides tool for automatic task

deployment. The second component is the console

server that enables the distant access to the

individual devices. The final element is the

specialised network hardware and virtual end

stations.

Virtual sever

Console sever

Network hardware

Figure 2: Block diagram of a remote lab.

2.3.1 Virtual Server

The virtual server is the first basic block component

and represents the virtual server Linux Debian that is

virtualised on VMware ESXi 5.1 on which are run

several basic services for ensuring the operation of

the laboratory. Firstly, this server provides the

platform for verification of users on the basis of

RADIUS protocol. Moreover, it is intended for

possible controlling of the access of individual

students to the infrastructure of the remote lab. The

database MySQL, in which the registration details of

individual users of the remote lab are saved, is used

as the data platform for RADIUS tool. The server

also provides the web-interface for operation of the

laboratory and networking devices management.

The internet application also offers tools for

planning the access to virtual laboratory. The

calendar displays the specific detail about when the

DCNET2014-InternationalConferenceonDataCommunicationNetworking

virtual laboratory is fully-utilised and when it is free

for possible reservation. The admin, who is the

lecturer, has the option to add new users, that ought

to have a beforehand approved time-slot to access

the infrastructure, to the RADIUS database server

according to the students’ requests.

Working with the distant laboratory requires

maintenance of the individual devices in order to

always create a new original configuration for each

student. This involves the deletion of the

configuration after each student’s session, as well as

the recording of the new chosen configuration before

another student starts his/hers session. The system

offers this function using the beforehand prepared

service package of commands (script). These are run

manually on the basis of creating and ending the

individual sessions. The system uses the connection

through SSH protocol on the console server in the

same way as the actual distant access to the

laboratory and it maintains the individual devices

through this console connection.

2.3.2 Console Server

The console server enables the necessary distant

access to individual devices which is not dependent

on the actual topology of the remote lab. However,

the usage of the standard access through the

protocols telnet or SSH can create a problem for the

running of such networking laboratory. Any

unthoughtful or wrongly configured change of the

topology can cause unavailability of a certain

network segment and the access to the devices could

be only obtained through a physical connection of a

serial link.

In our introduced and realised solution of the

remote lab connection the serial routes of individual

devices are connected to the console server. This

server is further attached using the IP protocol to the

university network, namely Internet, where it

functions as a SSH server. The user, who wishes to

access the given network device, is able to connect

to the console server using the SSH protocol from

anywhere at the university. On the basis of the given

port, the user is then connected through the SSH

connection directly to the console port of the

particular network device. This is the way in which

the access to the network device, that is independent

of the actual topology of the remote lab, is assured.

The access to the devices through the console is

in certain cases necessary even for the laboratory

practices. One of the examples can be the situation

when the student connects to the bootloader device

with the purpose to re-gain the access after

forgetting his/hers password. This can also be the

situation related to the maintaining server if the

student does not follow the set convention for using

passwords during the laboratory practices.

2.4 Network Devices of the Laboratory

The individual network device of the laboratory is

composed in the pilot operation of elements which

are intended for practicing laboratory tasks of the

course CCNP TSHOOT. Specifically, these

elements include routers Cisco 2801 and 2911 and

switches Cisco Catalyst 2960 and 3560. These are

connected into single-type topology which is used

across the whole course CCNP TSHOOT and can be

also applied for practicing of some of the topologies

which are to be found in the CCNP Routing and

Switching lectures.

In order to use the distant laboratory, the

topology is enlarged to enable the broadest usage of

the employed network device. Topology must offer

students full-value in terms of its working, in the

same way as if the students were physically present

in the laboratory and the sufficient modularity for

testing of own examples of different types. An

important characteristic of the suggested solution is

the independency from the specific network

elements as the console access is in the enterprise of

the network devices used as the standard. Therefore

this solution is easily scalable.

Networking devices can be replaced by new

ones, or expanded up to number of console ports,

that can be handled by a console terminal. The use

Figure 3: Interconnection between remote laboratory and

public network.

Internet

Management

erver

Virtual PC

_Ethernet

connections_

Console

terminal

controller

Virtual

PC switch

Remotelab

topology

Console

links

Internet

distribution

switch

RemoteLaboratoryforComputerNetworks

of multiple console terminal controllers is possible

and the management server is able to handle up to

50+ networking devices.

The basic CCNP TSHOOT exercises (topology)

were expanded by multiple end stations. These are

created as virtual devices connected into the network

topology of the distant laboratory, as well as into the

laboratory infrastructure as shown in the Fig. 3. The

virtual end stations are currently utilised using

Windows XP operating system which is adjusted to

minimise the demand on the hardware.

Instead of Windows XP system, it is of course

possible to use some other undemanding Linux

distributions, such as Puppy Linux or a system

without the graphic interface. Windows XP system

can be used in this case because for most students it

represents a common environment and therefore,

students can fully concentrate on the

accomplishment of their tasks without having to

solve specification of the configurations in Linux

systems. Using Remote Desktop Protocol (RDP),

students can in this way distantly access devices

which function as the local guests in the laboratory

network and in the same way as in the case of using

console server are available independently on the

actual configuration of the laboratory topology.

Another broadening of the former CCNP

TSHOOT topology is conducted by the addition of

elements from wireless networks. Examples of these

are the wireless controller and some centrally-

controlled Wi-Fi access points. In this way, it is

possible to use the distant laboratory for testing

network technologies which go beyond the CCNP

Routing and Switching course and are not usually

taught at FIM UHK. Therefore, it is also possible to

prepare students for courses which belong to the

Wireless family.

The last consistent solution of the topology is the

usage of Cisco Advanced Security Appliance (ASA)

elements. These offer students the platform for

testing configurations with the focus on the security

of enterprise networks. Among these can be found

the IPS technologies which follow the data running

in real time or the possibility to work with powerful

point-to-point and point-to-multipoint VPN tunnels.

The actual modularity of the network topology,

shown in the Fig. 4., of the distant laboratory is built

on the connection of multiple basic topologies

CCNP TSHOOT. In the pilot operation three basic

topologies enlarged by the wireless device of the

virtual end station are connected. It is possible to use

these links between individual topologies for

simulation in larger networks and they also enable to

create complex tasks which can be solved in student

teams. This topology was chosen because CCNP

TSHOOT course covers topics of both preceding

CCNP Route and CCNP Switch and is therefore

most universally usable. Interconnection of the

topologies and overall size of the remote laboratory

is a result of an effort to fully utilize the devices and

the amount of devices available.

In order to solve specific problems, for example

when finding the correct solution for graduate tasks,

it is possible to create an entirely different topology.

This requirement demands physical modification of

Figure 4: Remote lab topology – interconnection of three isolated CCNP TSHOOT topologies.

DCNET2014-InternationalConferenceonDataCommunicationNetworking

the former topology, but the actual topology still

enables a broad selection of simulations (i.e.

dynamic routing protocol adjustments, L2

redundancy simulations). These specific problems

usually require a lot of time and in ordinary

functioning of the laboratory even a few students

would fill up the capacity of the laboratory. Due to

the operation of the distant laboratory, it is possible

to add links to the current topology which will be

normally turned off, unless they are defined for

solving problems in advance. Students who would

work on complex problems can solve the problem in

a longer time scale during which they gradually

create the configuration which can be backed up and

reloaded again in the different sessions.

3 EVALUATION OF THE PILOT

OPERATION

The used system of the distant access to the

laboratory equipment is currently employed in the

pilot operation and tested for stability and reliability

of accesses. The significant advantage is the

utilisation of Remote lab controllers which provides

reliable connection with configuration interface of

individual elements, as well as it standardly uses the

special interface of the console for serial

communication. Moreover, remote lab controllers

also communicate with Linux server on which are

Network Policy Server RADIUS and MySQL

database, as well as management application, as

described above.

Before connecting remote lab to the educational

process of the faculty, it was not possible to use the

devices during the lecturers in the laboratory. This

presents approximately 6 hours a day during the

work days. Furthermore, it was also impossible to

access the elements during the hours when the

university was closed, which was not a problem

during the semester, but mainly during holidays. The

physical work in the laboratory also requires the

supervision of one of the lecturers or admins of the

lecture room. It was possible to eliminate these

disadvantages by introducing this system of the

distant access to the network elements. Under the

pilot operation, a group of students is preparing for

the CCNP Route certificate and uses the services of

the laboratory during the time when the access is

physically unfeasible. On the basis of the messages

from the Syslog server, the distant laboratory is used

on average 8 hours a day, including weekends.

Based on the student’s feedback, they sometimes

miss immediate lecturer assistance, such as in

standard courses. Overall student’s feedback is

positive, mainly because of the amount of time,

when they can work on the topology and practice

their skills. It is sometimes also their only possibility

to go through the course, so it is highly valued by

the students.

The disadvantage of the current solution is the

necessity of administration by lecturer who must

manually enable the time-slot of the chosen

laboratory task using the special web-interface. This

is where the disadvantage of the pilot operation is

obvious and it is therefore necessary cooperate with

university information systems, especially with

directory services, namely the implementation of

LDAP address services which opens up the

opportunities for full automation of the time-slot

reservation of individual elements (whole laboratory

tasks). This automation offers the possibility of

automatic choice of the type and level of the

laboratory task which the lecturer must set for the

current configuration during the time-slot

reservation of the device.

The current solution still cannot fully simulate

the conditions of the production computer network.

This is due to the fact that the laboratory network

still is not in the realistic operation on individual

links. In order to eliminate this disadvantage, one of

the possibilities is to broaden the topology by

generators of network operation. These can function

as a specialised hardware or another option is to use

one of the open source tools in form of another PC,

such as BackTrack Linux.

4 CONCLUSIONS

The realisation of the distant access to hardware

device and automatic pre-configuration of elements

for individual laboratory tasks seems to be an ideal

option for effective usage of specialised network

elements. This approach enables not only to broaden

the possibilities for highly specialised education

within the CCNP course, but also the possibility for

distance learning at FIM UHK. After the expansion

and interconnection of current model with

authentication systems of the university, it will be

possible to use the laboratory equipment even for

more complex tasks in courses within the computer

network III and IV which currently cannot be

realised (other than for practice with lecturer) due to

the time limit on access to the laboratory. On the

basis of the experiences gained from the pilot

operation, this platform can become an essential part

RemoteLaboratoryforComputerNetworks

of the education tools in various levels of teaching at

FIM UHK. Another important advantage of the

remote lab would be the possibility to use it for final

academic works which are much more practically

oriented because of the emphasis on team work and

practical usage. Due to the distant access, the

opportunities for effective usage of laboratory

equipment at FIM UHK are significantly improving.

ACKNOWLEDGEMENTS

This work and contribution is supported by the

project of the European Operational Programme

Education for Competitiveness project

CZ.1.07/2.3.00/45.0014 and by the project No. CZ.

1.07/2.2.00/28.0327 Innovation and support of

doctoral study program (INDOP), financed from EU

and Czech Republic funds.

This work and the contribution were supported

by project “SP/2014/05 – Smart Solutions for

Ubiquitous Computing Environments” from

University of Hradec Kralove.

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RemoteLaboratoryforComputerNetworks