ISO/FDIS 14908-1
(Main)Interconnection of information technology equipment — Control Network Protocol — Part 1: Protocol Stack
Interconnection of information technology equipment — Control Network Protocol — Part 1: Protocol Stack
ISO 14908-1:2011 applies to a communication protocol for local area control networks. The protocol provides peer-to-peer communication for networked control and is suitable for implementing both peer-to-peer and master-slave control strategies. This specification describes services in layers 2 to 7. In the layer 2 (data link layer) specification, it also describes the MAC sub-layer interface to the physical layer. The physical layer provides a choice of transmission media. The interface described in ISO 14908-1:2011 supports multiple transmission media at the physical layer. In the layer 7 specification, it includes a description of the types of messages used by applications to exchange application and network management data.
Interconnexion des équipements des technologies de l'information — Protocole de réseau de contrôle — Partie 1: Pile de protocole
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Standards Content (Sample)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 14908-1
ISO/TC 205
Interconnection of information
Secretariat: ANSI
technology equipment — Control
Voting begins on:
Network Protocol —
2011-01-04
Part 1:
Voting terminates on:
2011-03-04
Protocol Stack
Interconnexion des équipements des technologies de l'information —
Protocole de réseau de contrôle —
Partie 1: Pile de protocole
Please see the administrative notes on page iii
RECIPIENTS OF THIS DRAFT ARE INVITED TO
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ING DOCUMENTATION.
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BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 14908-1:2011(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
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LIGHT OF THEIR POTENTIAL TO BECOME STAN-
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©
NATIONAL REGULATIONS. ISO 2011
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ISO/FDIS 14908-1:2011(E)
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ISO/FDIS 14908-1:2011(E)
In accordance with the provisions of Council Resolution 15/1993, this document is circulated in the
English language only.
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ISO/FDIS 14908-1:2011(E)
Contents Page
Foreword.vi
Introduction.vii
1 Scope .1
2 Terms and definitions .1
3 Symbols and abbreviations .3
3.1 Symbols and graphical representations .3
3.2 Abbreviations.4
4 Overview of protocol layering .5
5 MAC sublayer.7
5.1 Service provided.7
5.2 Interface to the link layer .7
5.3 Interface to the physical layer .8
5.4 MPDU format .9
5.5 Predictive p-persistent CSMA — overview description.9
5.6 Idle channel detection . 10
5.7 Randomising . 11
5.8 Backlog estimation. 11
5.9 Optional priority. 11
5.10 Optional collision detection. 13
5.11 Beta1, Beta2 and Preamble Timings. 13
6 Link layer . 15
6.1 Assumptions . 15
6.2 Service provided. 15
6.3 CRC . 15
6.4 Transmit algorithm . 17
7 Network layer . 17
7.1 Assumptions . 17
7.2 Service provided. 18
7.3 Service interface . 19
7.4 Internal structuring of the network layer. 19
7.5 NPDU format. 19
7.6 Address recognition. 20
7.7 Routers . 20
7.8 Routing algorithm. 21
7.9 Learning algorithm — subnets. 21
8 Transaction control sublayer . 21
8.1 Assumptions . 21
8.2 Service provided. 22
8.3 Service interface . 22
8.4 State variables. 23
8.5 Transaction control algorithm. 23
9 Transport layer. 23
9.1 Assumptions . 23
9.2 Service provided. 24
9.3 Service interface . 24
9.4 TPDU types and formats . 25
9.5 Protocol diagram . 26
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ISO/FDIS 14908-1:2011(E)
9.6 Transport protocol state variables .26
9.7 Send algorithm .27
9.8 Receive algorithm.27
9.9 Receive transaction record pool size and configuration engineering.27
10 Session layer .29
10.1 Assumptions.29
10.2 Service provided.29
10.3 Service interface.30
10.4 Internal structure of the session layer .30
10.5 SPDU types and formats.31
10.6 Protocol timing diagrams .32
10.7 Request-response state variables .35
10.8 Request-response protocol — client part.35
10.9 Request-response protocol — server part .35
10.10 Request-response protocol timers.35
10.11 Authentication protocol.36
10.12 Encryption algorithm .36
10.13 Retries and the role of the checksum function .36
10.14 Random Number Generation .37
10.15 Using Authentication .37
11 Presentation/application layer .37
11.1 Assumptions.37
11.2 Service provided.37
11.3 Service interface.38
11.4 APDU types and formats .39
11.5 Protocol diagrams.40
11.6 Application protocol state variables .41
11.7 Request - response messaging in offline state.41
11.8 Network variables.42
11.9 Error notification to the application program.43
12 Network management & diagnostics .43
12.1 Assumptions.43
12.2 Services provided.44
12.3 Network management and diagnostics application structure.44
12.4 Node states .44
12.5 Using the network management services.45
12.6 Using router network management commands.48
12.7 NMPDU formats and types .49
12.8 DPDU types and formats .70
Annex A (normative) Reference implementation.75
Annex B (normative) Additional Data Structures .356
Annex C (informative) Behavioral characteristics.378
Annex D (normative) PDU summary.382
Annex E (normative) Naming and addressing.384
Annex F (normative) List of patents that pertain to this International Standard .388
Bibliography.390
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ISO/FDIS 14908-1:2011(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14908-1 was prepared by CEN/TC 247, was adopted, under the fast track procedure, by joint Technical
Committee ISO/IEC JTC 1, Information technology, and was assigned to SC 25, Interconnection of
information technology equipment. It was then transferred to ISO/TC 205, Building environment design.
ISO 14908 consists of the following parts, under the general title Interconnection of information technology
equipment — Control Network Protocol:
⎯ Part 1: Protocol Stack
⎯ Part 2: Twisted-pair communication
⎯ Part 3: Power line channel specification
⎯ Part 4: IP communication
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ISO/FDIS 14908-1:2011(E)
Introduction
This International Standard has been prepared to provide mechanisms through which various vendors of local
area control networks may exchange information in a standardized way. It defines communication capabilities.
This International Standard is to be used by anyone involved in design, manufacture, engineering, installation
and commissioning activities.
The International Organization for Standardization (ISO) and the International Electrotechnical
Commission (IEC) draw attention to the fact that it is claimed that compliance with this International Standard
may involve the use of patents held by Echelon Corporation.
ISO and the IEC take no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured ISO and the IEC that they are willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect,
the statement of the holder of the patent rights is registered with ISO and the IEC. Information may be
obtained from:
Echelon Corporation, 4015 Meridian Avenue, San Jose, CA 94304, USA, phone +1-408-938-5234,
fax: +1-408-790-3800, http://www.echelon.com.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 14908-1:2011(E)
Interconnection of information technology equipment —
Control Network Protocol —
Part 1:
Protocol Stack
1 Scope
This part of ISO 14908 applies to a communication protocol for local area control networks. The protocol
provides peer-to-peer communication for networked control and is suitable for implementing both peer-to-peer
and master-slave control strategies. This specification describes services in layers 2 to 7. In the layer 2 (data
link layer) specification, it also describes the MAC sub-layer interface to the physical layer. The physical layer
provides a choice of transmission media. The interface described in this part of ISO 14908 supports multiple
transmission media at the physical layer. In the layer 7 specification, it includes a description of the types of
messages used by applications to exchange application and network management data.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE Most of the terms are commonly used and have the same meaning in both the general and the standard
context. However, for some terms, there are subtle differences. For example, in general, bridges do selective forwarding
based on the layer 2 destination address. There are no layer 2 addresses in this standard protocol, so bridges forward all
packets, as long as the domain address in the packet matches a domain of which the bridge is a member. Routers, in
general, perform network address modification so that two protocols with the same transport layer but different network
layers can be connected to form a single logical network. Routers of this International Standard may perform network
address modification, but, typically, they only examine the network address fields and selectively forward packets based
on the network layer address fields.
2.1
channel
physical unit of bandwidth linking one or more communication nodes
NOTE See Annex E for further explanation of the relationship between a channel and a subnet.
2.2
physical repeater
device that reconditions the incoming physical layer signal on one channel and transmits it on to another
channel
2.3
store-and-forward repeater
device that stores and then reproduces data packets on a second channel
2.4
bridge
device that connects two channels (x and y), forwards all packets from x to y and vice versa, as long as the
packets originate on one of the domain(s) to which the bridge belongs
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ISO/FDIS 14908-1:2011(E)
2.5
configuration
non-volatile information used by the device to customise its operation
NOTE There is configuration data for the correct operation of the protocol in each device and, optionally, for
application operation. The network configuration data stored in each device has a checksum associated with the data.
Examples of network configuration data are node addresses, communication media parameters such as priority settings,
etc. Application configuration information is application-specific.
2.6
domain
virtual network that is the network unit of management and administration
NOTE Group (2.10) and subnet (2.8) addresses are assigned by the administrator responsible for the domain and
have meaning only in the context of that domain.
2.7
flexible domain
transitory domain entry at a node used in conjunction with Unique_Node_ID and broadcast addressing
NOTE A node responds to a Unique_Node_ID-addressed message if the address matches, regardless of the domain
on which the message was sent. To respond so that the sender receives it, the response must be sent on the domain in
which it was received. Furthermore, this domain must be remembered for the duration of the transaction so that duplicate
detection of any retries is possible. How many flexible domain entries a node supports is up to the implementation.
However, a minimum of one is required.
2.8
subnet
set of nodes accessible through the same link layer protocol, a routing abstraction for a channel
NOTE In this International Standard, subnets are limited to a maximum of 127 nodes.
2.9
node
abstraction for a physical node that represents the highest degree of address resolvability on a network
NOTE A node is identified (addressed) within a subnet by its (logical) node identifier. A physical node can belong to
more than one subnet. When it does, it is assigned one (logical) node number for each subnet to which it belongs. A
physical node can belong to at most two subnets; these subnets must be in different domains. A node can also be
identified (absolutely) within a network by its Unique_Node_ID.
2.10
group
uniquely identifiable set of nodes within a domain
NOTE Within this set, individual members are identified by their member number. Groups facilitate one-to-many
communication and are intended to support functional addressing.
2.11
router
device that routes data packets to their respective destinations by selectively forwarding from subnet to subnet
NOTE A router always connects two (sets of) subnets; routers may modify network layer address fields. Routers can
be set to one of four modes: repeater mode, bridge mode, learning mode, and configured mode. In repeater mode,
packets are forwarded if they are received with no errors. In bridge mode, packets are forwarded if they are received with
no errors and match a domain of which the router is a member. Routers in learning mode learn the topology by examining
packet traffic, while routers that are set to configured mode have the network topology stored in their memory and make
their routing decisions solely upon the contents of their configured tables.
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ISO/FDIS 14908-1:2011(E)
2.12
(application) gateway
gateway that interconnects networks at their highest protocol layers (often two different protocols)
NOTE Two domains can also be connected through an application gateway.
2.13
Beta1
β
1
period immediately following the end of a packet cycle
NOTE A node attempting to transmit data packets monitors the state of the channel and, if it detects no transmission
during the Beta1 period, determines the channel to be idle.
2.14
Beta2
β
2
randomising slot
NOTE A node wishing to transmit data packets generates a random delay T. This delay is an integer number of
randomising slots of duration Beta2.
2.15
network variable
variable in an application program whose value is automatically propagated over the network whenever a new
value is assigned to it
2.16
Standard Network Variable Types
SNVTs
variables with agreed-upon semantics
NOTE These variables are interpreted by all applications in the same way, and are the basis for interoperability.
Definition of specific SNVTs is beyond the scope of this International Standard.
2.17
manual service request message
network management message containing a node's Unique_Node_ID
NOTE Used by a network management device that receives this message to install and configure the node. May be
generated by application or system code. May be triggered by an external hardware event, e.g. driving a “manual service
request” input low.
2.18
transaction
sequence of messages that are correlated together
NOTE A request and the responses to the request are all part of a single transaction. A transaction succeeds when
all the expected messages from every node involved in the transaction are received at least once. A transaction fails in
this International Standard if any of the expected messages within the transaction are not received. Retries of messages
within a transaction are used to increase the probability of success of a transaction in the presence of transient errors.
3 Symbols and abbreviations
3.1 Symbols and graphical representations
Figure 1 shows the basic topology of networks based on this protocol and the symbolic representations used
in this International Standard.
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ISO/FDIS 14908-1:2011(E)
Figure 1 — Network topology & symbols
The layering of this protocol is described using standard OSI terminology, as shown in Figure 2.
Figure 2 — Protocol terminology
3.2 Abbreviations
⎯ CNP Control Network Protocol
The Protocol Data Unit (PDU) abbreviations used throughout this International Standard are:
⎯ PPDU Physical Protocol Data Unit, or frame
⎯ MPDU MAC Protocol Data Unit, or frame
⎯ LPDU Link Protocol Data Unit, or frame
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ISO/FDIS 14908-1:2011(E)
⎯ NPDU Network Protocol Data Unit, or packet
⎯ TPDU Transport Protocol Data Unit, or a message/ack
⎯ SPDU Session Protocol Data Unit, or request/response
⎯ NMPDU Network Management Protocol Data Unit
⎯ DPDU Diagnostic Protocol Data Unit
⎯ APDU Application Protocol Data Unit
⎯ FSM Finite State Machine (diagram)
Annex D (PDU Summary) contains the details of these PDUs.
4 Overview of protocol layering
The protocol specified by this Standard consists of the layers shown in Figure 3. Each layer is described
below.
Multiple physical layer protocols and data encoding methods are allowed in s
...
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