3 Engineering IoT Networks
139
Thread guarantees a high level of security. Only devices that are specifically
authenticated can join the network. All communications through the network are
secured with a network key. Thread states that there is no single point of failure in
its system. However, if the network is only set up with one edge router, then this can
become a single point of failure. The edge router or another router can assume the
role of leader for specific functions. If the leader fails, another router or edge router
will take its place. This is the main way that Thread guarantees no single point of
failure.
3.3.16 ISA100.11a
ISA100.11a is a competitor of WirelessHART in wireless networks for process
control. It was developed by the International Society of Automation (ISA) and
standardized as IEC 62734 [33] in 2014.
The ISA100.11a Physical Layer is taken from the IEEE 802.15.4-2006 2.4 GHz
DSSS Physical Layer. The Data Link Layer is unique to ISA100.11a and uses a noncompliant form of the IEEE802.15.4 MAC. It implements graph routing, frequency
hopping and time-slotted time domain multiple access features. The forwarding
of messages within the wireless network is performed at the Data Link Layer by
using a mesh approach. Since the TDMA slot size and the ACK format are not
fully specified, it is possible that two ISA100.11a devices may not be able to
communicate. ISA100.11a leverages 6LoWPAN protocol and addressing for routing
messages outside the wireless domain. The ISA100.11a Transport Layer consists in
a connectionless service based on UDP with an enhanced message integrity check
and end-to-end security. Currently no process control Application Layer is specified.
ISA100.11a and WirelessHART share some similarities and exhibit some differences [33]. Each of the technologies uses the IEEE 802.15.4 standard at
Physical Layer. WirelessHART also uses the IEEE802.15.4-2006 Data Link Layer.
ISA100.11a uses a modified, non-compliant version of the same layer. Both have
similar mechanisms for forming the wireless mesh network and transporting data to
and from the gateway. These networks are very low power. The radio spectrum used
in each is in the 2.4 GHz band and does not require licensing. The radio technology
utilizes a combination of channel hopping and Direct Sequence Spread Spectrum to
achieve coexistence with other users of the same spectrum. Networks can occupy
the same physical space and radio spectrum without blocking one another. Both
specifications use similar graph routing, source routing, security, and centralized
network management functions.
The major differences between WirelessHART and ANSI/ISA100.11a-2011
can be directly traced to the differences in the goals of each standard. Whereas
WirelessHART is focused on providing a wireless medium for HART protocol,
ISA100.11a is designed to provide flexibility by offering a variety of build options
to the manufacturer and run-time options for customizing the operation of the
139
Thread guarantees a high level of security. Only devices that are specifically
authenticated can join the network. All communications through the network are
secured with a network key. Thread states that there is no single point of failure in
its system. However, if the network is only set up with one edge router, then this can
become a single point of failure. The edge router or another router can assume the
role of leader for specific functions. If the leader fails, another router or edge router
will take its place. This is the main way that Thread guarantees no single point of
failure.
3.3.16 ISA100.11a
ISA100.11a is a competitor of WirelessHART in wireless networks for process
control. It was developed by the International Society of Automation (ISA) and
standardized as IEC 62734 [33] in 2014.
The ISA100.11a Physical Layer is taken from the IEEE 802.15.4-2006 2.4 GHz
DSSS Physical Layer. The Data Link Layer is unique to ISA100.11a and uses a noncompliant form of the IEEE802.15.4 MAC. It implements graph routing, frequency
hopping and time-slotted time domain multiple access features. The forwarding
of messages within the wireless network is performed at the Data Link Layer by
using a mesh approach. Since the TDMA slot size and the ACK format are not
fully specified, it is possible that two ISA100.11a devices may not be able to
communicate. ISA100.11a leverages 6LoWPAN protocol and addressing for routing
messages outside the wireless domain. The ISA100.11a Transport Layer consists in
a connectionless service based on UDP with an enhanced message integrity check
and end-to-end security. Currently no process control Application Layer is specified.
ISA100.11a and WirelessHART share some similarities and exhibit some differences [33]. Each of the technologies uses the IEEE 802.15.4 standard at
Physical Layer. WirelessHART also uses the IEEE802.15.4-2006 Data Link Layer.
ISA100.11a uses a modified, non-compliant version of the same layer. Both have
similar mechanisms for forming the wireless mesh network and transporting data to
and from the gateway. These networks are very low power. The radio spectrum used
in each is in the 2.4 GHz band and does not require licensing. The radio technology
utilizes a combination of channel hopping and Direct Sequence Spread Spectrum to
achieve coexistence with other users of the same spectrum. Networks can occupy
the same physical space and radio spectrum without blocking one another. Both
specifications use similar graph routing, source routing, security, and centralized
network management functions.
The major differences between WirelessHART and ANSI/ISA100.11a-2011
can be directly traced to the differences in the goals of each standard. Whereas
WirelessHART is focused on providing a wireless medium for HART protocol,
ISA100.11a is designed to provide flexibility by offering a variety of build options
to the manufacturer and run-time options for customizing the operation of the