Year 1, Sem 2: Data Communication and Network Routing Report

This report provides a detailed analysis of data communication and network routing, specifically focusing on the Controller Area Network (CAN bus). It begins with an introduction to the CAN bus, explaining its function as a vehicle bus designed for communication between devices and microcontrollers. The report then discusses the working principles of the CAN bus, including its layered architecture (data link, physical, and application layers) and the structure of a standard CAN frame. It outlines the strengths of CAN bus, such as its ability to reduce wiring issues, support high data rates, and operate in adverse electrical environments. The report also highlights the weaknesses of CAN bus, including its limited maximum length and node capacity, along with the need for specialized software development and maintenance. Furthermore, it addresses the risks associated with CAN bus, particularly its vulnerability to malicious attacks due to its broadcast nature and lack of intrinsic security tools. The report concludes by summarizing the key findings and reiterating the importance of understanding the CAN bus in modern automotive and industrial applications.

Running head: DATA COMMUNICATION AND NETWORK ROUTING
DATA COMMUNICATION AND NETWORK ROUTING
Name of student:
Name of university:
Author’s note:

1DATA COMMUNICATION AND NETWORK ROUTING
Table of Contents
Introduction....................................................................................................................2
Discussion......................................................................................................................2
Working principle of CAN bus..................................................................................2
Strength of CAN bus..................................................................................................4
Weakness of CAN bus...............................................................................................5
Risks associated with CAN bus.................................................................................5
Conclusion......................................................................................................................6
References......................................................................................................................7
Appendix........................................................................................................................9

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Introduction
This report aims to discuss the topic data communication and network routing. The
selected technology for this document is the Controller Area networking (CAN Bus). A brief
discussion of the fundamental working method of CAN bus is provided in this report. The
advantages and the weaknesses and the potential risks of CAN bus is briefly discussed in this
report. Lastly, this report concludes with an appropriate conclusion for this report.
A CAN bus or Controller Area Network is a strong standard of vehicle bus that is
designed for allowing the devices and microcontrollers in communicating with each other in
several applications without any host computer (Davis et al. 2013). The CAN bus is a
protocol that is protocol based and it was designed fundamentally for multiplex electrical
wiring in the automobiles for saving copper and now it is used it several fields.
Discussion
Working principle of CAN bus
A CAN bus or Controller Area Network bus is a system of communication that is
made for the intercommunication among vehicles. This bus allows the communication among
microcontrollers and several kinds of devices among one another in real time and without any
host computer. A CAN bus do not need any schemes of addressing as the network nodes use
distinct identifiers (Kelkar and Kamal 2014). This delivers the information to the nodes about
the urgency and the priority of the message that is transmitted. The architecture of CAN bus
consists of these following layers:
 Data link layer: the linking of the actual data to the protocol in the terms of
receiving, sending and data validation is done in this layer.
 Physical layer: The actual hardware is included in this section.

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 Application layer: This layer interacts with the operating system or the CAN
devices application
A standard frame of CAN consists of these following bits:
Start of Frae me or SOF: This is the origin point of the message.
RTR: It stands for Remote Transmission Request. This node is activated when some
information is required from a node.
Identifier: The priority of the messages are decided in this. The priority of the lower binary
value is the highest (Zhang et al. 2017).
DLC: It stands for Data Length Code. The data length is defined by this.
IDE: Single Identification Extension. The more dominant this is, it is perceived that the
identifier of CAN with no extension is being sent.
Data: Transmission of upto 64 bits can be done
R0: This is the reserve bit
ACK: this means Acknowledge. When the correct message is transmitted, this is dominant.
CRC: This stands for Cyclic Redundancy Check. The checksum is contained in this.
A CAN bus utilises two dedicated wires to communicate among one another. The respective
wires are CAN low and CAN high. The controller of CAN is linked with all the components
of the network using two wires (Cena et al. 2013). Each node of the network has a distinct
identifier. All the ECUs on the bus are efficiently in parallel connection and this is the reason
why all the data is visible to all the nodes. The response of any node is received when it
detects its respective identifier. The individual nodes can be detached from the network
without disturbing other nodes (Shah et al. 2013). When a CAN bus is Idle, both the lines

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carry 2.5V. When the transmission of data bits is done, the CAN low line descends up to
1.25V and the CAN high line increases up to 3.75V, and therefore it generates a differential
of 2.5V among the lines, and each CAN line is connected to another, and not the vehicle
ground. As the communication depends on the differential voltage among the two lines, the
CAN bus is found to be NOT sensitive to the electrical fields, inductive spikes or any other
noise. This is the reason why CAN bus is preferred on mobile equipment for communications
that are networked. CAN bus can be used for providing power to the CAN. Or any power
supply for the modules of the CAN bus can be structured distinctly (Mubeen, Mäki-Turja and
Sjödin 2015). The wiring of the power supply can be totally distinct or the integration into the
same bus can be done in the same cable as the lines of CAN bus and lead to a single 4-wire
cable. The nature of the communications of CAN bus permits all the modules to receive and
transmit the data on bus. Data can be transmitted by any module, which is received by all the
other modules. It is essential to allocate the bandwidth of CAN bus to the systems that are
critical to safety (Shin 2014). The nodes are usually assigned to one of a number of levels of
priority.
Strength of CAN bus
The following are the strengths of CAN bus:
 It is utilised for reducing the issue of wiring in several automobiles application.
 The CAN bus permits the data rate upto 1Mbps. CAN FD or flexible data rate
wersion allows more than 2Mbps speed. CAN FD support huge bandwidth which is
approximately eight times greater than the basic CAN bus.
 8 bytes are supported by the Standard CAN protocols, while the CAN FD protocol
backs 64 bytes in the part of data field.
 Overall time and cost is reduced due to the simple and lower wiring and the utilisation
of flash programming (Groza and Murvay 2013).

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 It can work in adverse electrical environments
 Lost messages can be retransmitted automatically using CAN bus
Weakness of CAN bus
The disadvantages of CAN bus can be the following:
 The maximum length that is supported by the CAN bus is 40 meters
 Even though the maximum nodes number is not determined in the network, it can
support a maximum 64 nodes due to the electrical loading
 It requires additional expenditure for the development of software and the
maintenance
 Undesirable interactions among the nodes can be found in this network
 As the network needs to be contained in a topology, the stubs are limited
increasingly (Chan et al. 2014)
 The removal of nodes requires the utilisation of termination resistors of value of
120 Ohm at the suitable places on the CAN bus
 For reducing the issues of integrity of signal like the reflections, CAN bus needs
to be properly terminated at both ends with the resistors.
Risks associated with CAN bus
Several researches were conducted and it was observed that the CAN buses are not
produced for withstanding attacks with malicious intent, instead these buses are created for
reliability (Hu et al. 2013). Due to the shared nature of broadcasting, the risks in the CAN
buses increases. With the alteration of the messages of the CAN, the control of the car can be
gained by the attacker. Researchers demonstrated this vulnerability by controlling the steering
wheel of Jeep by spoofing the assist of parking (Xie et al. 2013). The CAN is of significantly
fragile in nature and it can be easily overridden by any attacker. The messages of

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speedometer that are sent by other ECUs can be easily detected and the attacker and they can
assert a bus state that is dominant, which makes all the other receivers reject the messages
that are sent to them as invalid. Even the brake control can be compromised when the car is
travelling at a high speed. The Read Memory By Address is one more service of diagnosis
that can be misused by the attackers for reading the arbitrary pieces of the address space of
ECU. The sensitive values such as the keys of authentication can be leaked easily with the
use of this service. A risk that is associated with the CAN bus is that the CAN does not
possess any intrinsic security tool. They are susceptible to the attacks from any surface of
physical attacks like OBD-II port and the surfaces of wireless attack such as the GPS,
Bluetooth, GSM module, Wi-Fi. In a CAN, the broadcasting of each message is done over a
bus and the nodes decide whether to accept the message or discard it (Mubeen, Mäki-Turja
and Sjödin 2014). It creates the availability of every message on every ECU on the bus.
Conclusion
Therefore, it can be concluded that the Controller Area Network is used in the
automobiles for enhancing the capability of the vehicles. A CAN bus or Controller Area
Network is a strong standard of vehicle bus that is designed for allowing the devices and
microcontrollers in communicating with each other in several applications without any host
computer. A CAN bus or Controller Area Network bus is a system of communication that is
made for the intercommunication among vehicles. This bus allows the communication among
microcontrollers and several kinds of devices among one another in real time and without any
host computer. Due to the shared nature of broadcasting, the risks in the CAN buses
increases. With the alteration of the messages of the CAN, the control of the car can be
gained by the attacker. Researchers demonstrated this vulnerability by controlling the steering
wheel of Jeep by spoofing the assist of parking. The CAN is of significantly fragile in nature
and it can be easily overridden by any attacker.

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References
Cena, G., Bertolotti, I.C., Hu, T. and Valenzano, A., 2013. Fixed-length payload encoding for
low-jitter controller area network communication. IEEE Transactions on Industrial
Informatics, 9(4), pp.2155-2164.
Chan, M.C., Chen, C., Huang, J.X., Kuo, T., Yen, L.H. and Tseng, C.C., 2014, April.
OpenNet: A simulator for software-defined wireless local area network. In Wireless
Communications and Networking Conference (WCNC), 2014 IEEE (pp. 3332-3336). IEEE.
Davis, R.I., Kollmann, S., Pollex, V. and Slomka, F., 2013. Schedulability analysis for
Controller Area Network (CAN) with FIFO queues priority queues and gateways. Real-Time
Systems, 49(1), pp.73-116.
Groza, B. and Murvay, S., 2013. Efficient protocols for secure broadcast in controller area
networks. IEEE Transactions on Industrial Informatics, 9(4), pp.2034-2042.
Hu, C., Zhang, N., Li, H., Cheng, X. and Liao, X., 2013. Body area network security: a fuzzy
attribute-based signcryption scheme. IEEE journal on selected areas in
communications, 31(9), pp.37-46.
Kelkar, S. and Kamal, R., 2014. Adaptive fault diagnosis algorithm for controller area
network. IEEE Transactions on Industrial Electronics, 61(10), pp.5527-5537.
Mubeen, S., Mäki-Turja, J. and Sjödin, M., 2014. MPS-CAN analyzer: Integrated
implementation of response-time analyses for Controller Area Network. Journal of Systems
architecture, 60(10), pp.828-841.
Mubeen, S., Mäki-Turja, J. and Sjödin, M., 2015. Integrating mixed transmission and
practical limitations with the worst-case response-time analysis for Controller Area
Network. Journal of Systems and Software, 99, pp.66-84.

8DATA COMMUNICATION AND NETWORK ROUTING
Shah, M.N., Husain, A.R., Punekkat, S. and Dobrin, R.S., 2013. A new error handling
algorithm for controller area network in networked control system. Computers in
Industry, 64(8), pp.984-997.
Shin, C., 2014, February. A framework for fragmenting/reconstituting data frame in
Controller Area Network (CAN). In Advanced Communication Technology (ICACT), 2014
16th International Conference on (pp. 1261-1264). IEEE.
Xie, Y., Zeng, G., Chen, Y., Kurachi, R., Takada, H. and Li, R., 2013. Worst case response
time analysis for messages in controller area network with gateway. IEICE TRANSACTIONS
on Information and Systems, 96(7), pp.1467-1477.
Zhang, Y., Chen, M., Guizani, N., Wu, D. and Leung, V.C., 2017. SOVCAN: Safety-oriented
vehicular controller area network. IEEE Communications Magazine, 55(8), pp.94-99.

9DATA COMMUNICATION AND NETWORK ROUTING
Appendix
Figure 1: CAN module