U.S. patent application number 14/577115 was filed with the patent office on 2015-11-19 for determining thenetwork topology of a communication network.
This patent application is currently assigned to ABB RESEARCH LTD. The applicant listed for this patent is ABB RESEARCH LTD. Invention is credited to Hubert KIRRMANN.
Application Number | 20150333966 14/577115 |
Document ID | / |
Family ID | 46384186 |
Filed Date | 2015-11-19 |
United States Patent
Application |
20150333966 |
Kind Code |
A2 |
KIRRMANN; Hubert |
November 19, 2015 |
DETERMINING THENETWORK TOPOLOGY OF A COMMUNICATION NETWORK
Abstract
A network management agent, device or module determine the
network topology of a communication network based on at least one
neighbor network or end device identity and corresponding network
link communication delay collected from, determined by, and stored
in a Management Information Base of, at least one first network
device of the communication network. Neighbor identities and
communication delays are determined according to the IEEE 1588
standard.
Inventors: |
KIRRMANN; Hubert; (Dattwil,
CH) |
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Applicant: |
Name |
City |
State |
Country |
Type |
ABB RESEARCH LTD |
Zurich |
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CH |
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Assignee: |
ABB RESEARCH LTD
Zurich
CH
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Prior
Publication: |
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Document Identifier |
Publication Date |
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US 20150156072 A1 |
June 4, 2015 |
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Family ID: |
46384186 |
Appl. No.: |
14/577115 |
Filed: |
December 19, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/EP2013/063003 |
Jun 21, 2013 |
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14577115 |
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Current U.S.
Class: |
370/254 |
Current CPC
Class: |
H04L 41/0206 20130101;
H04L 41/046 20130101; Y04S 40/168 20130101; H04L 41/12 20130101;
H04L 43/0852 20130101; Y04S 40/164 20130101; H04L 7/00 20130101;
Y04S 40/00 20130101 |
International
Class: |
H04L 12/24 20060101
H04L012/24; H04L 7/00 20060101 H04L007/00 |
Claims
1. A method for determining the network topology of a communication
network including at least one first network device connected
through at least one network link to at least one neighboring
network device, the at least one first network device and the at
least one neighboring network device being synchronized according
to the IEEE 1588 standard, the method comprising: determining, by
each of the at least one first network device, an identity of the
at least one neighboring network device and a communication delay
of the at least one network link, respectively; and collecting, by
a network manager, the respective determined identity and
communication delay, and determining a network topology of the
communication network including a length of the at least one
network link therefrom.
2. The method according to claim 1, comprising: transmitting, by
the at least one first network device, a peer delay request message
to the at least one neighboring network device; transmitting, by
the at least one neighboring network device, a peer delay response
message to the at least one first network devices; and determining,
by the at least one first network device, the at least one
communication delay between the at least one first network device
and the at least one neighboring network device from the peer delay
request message and the peer delay response message.
3. The method according to claim 1, comprising: receiving a
broadcast synchronization message on a first network interface of
the at least one first network device; transmitting, by the at
least one first network device, the synchronization message on at
least one second network interface to the at least one neighboring
network device; transmitting, by the at least one neighboring
network device, a response message to the at least one first
network device; and determining, by the at least one first network
device, the at least one communication delay between the at least
one first network device and the at least one neighboring network
devices from the synchronization message and the response
message.
4. The method according to claim 1, comprising: generating a
graphical network diagram showing an actual network topology of the
communication network.
5. The method according to claim 1, comprising: updating a
graphical network diagram showing the design of the network
topology of the communication network.
6. The method according to claim 1, comprising: collecting the at
least one communication delay through SNMP (SNMP: Simple Network
Management Protocol) from a MIB (MIB: Management Information Base)
stored in the at least one first network devices, together with a
MAC address (MAC: Media Access Control) of the at least one first
network device and the MAC address of the corresponding at least
one neighboring network device.
7. The method according to claim 2, comprising: generating a
graphical network diagram showing an actual network topology of the
communication network.
8. The method according to claim 2, comprising: updating a
graphical network diagram showing the design of the network
topology of the communication network.
9. The method according to claim 2, comprising: collecting the at
least one communication delay through SNMP (SNMP: Simple Network
Management Protocol) from a MIB (MIB: Management Information Base)
stored in the at least one first network devices, together with a
MAC address (MAC: Media Access Control) of the at least one first
network device and the MAC address of the corresponding at least
one neighboring network device.
10. The method according to claim 3, comprising: generating a
graphical network diagram showing an actual network topology of the
communication network.
11. The method according to claim 3, comprising: updating a
graphical network diagram showing the design of the network
topology of the communication network.
12. The method according to claim 3, comprising: collecting the at
least one communication delay through SNMP (SNMP: Simple Network
Management Protocol) from a MIB (MIB: Management Information Base)
stored in the at least one first network devices, together with a
MAC address (MAC: Media Access Control) of the at least one first
network device and the MAC address of the corresponding at least
one neighboring network device.
13. The method according to claim 4, comprising: updating a
graphical network diagram showing the design of the network
topology of the communication network.
14. The method according to claim 13, comprising: collecting the at
least one communication delay through SNMP (SNMP: Simple Network
Management Protocol) from a MIB (MIB: Management Information Base)
stored in the at least one first network devices, together with a
MAC address (MAC: Media Access Control) of the at least one first
network device and the MAC address of the corresponding at least
one neighboring network device.
15. A network management agent for determining the network topology
of a communication network including at least one first network
device, each first network device being connected through at least
one network link to at least one neighboring network device, the at
least one first network device and the at least one neighboring
network device being synchronized according to the IEEE 1588
standard, the network management agent having a processor
configured to, by executing a computer program tangibly recorded on
a non-transitory computer-readable recording medium of the network
management agent: collect, from each of the at least one first
network device, an identity of the at least one neighboring network
device and a communication delay of the at least one network link,
respectively; and determine the network topology of the
communication network including a length of the at least one
network link therefrom.
16. A non-transitory computer-readable recording medium having a
computer program tangibly recorded thereon that, when executed by a
processor of a computer processing device, cause the processor to
carry out a method for determining the network topology of a
communication network including at least one first network device
connected through at least one network link to at least one
neighboring network device, the at least one first network device
and the at least one neighboring network device being synchronized
according to the IEEE 1588 standard, the method comprising:
determining, by each of the at least one first network device, an
identity of the at least one neighboring network device and a
communication delay of the at least one network link, respectively;
and collecting, by a network manager, the respective determined
identity and communication delay, and determining a network
topology of the communication network including a length of the at
least one network link therefrom.
Description
RELATED APPLICATIONS
[0001] This application claims priority as a continuation
application under 35 U.S.C. .sctn.120 to PCT/EP2013/063003, which
was filed as an International Application on Jun. 21, 2013
designating the U.S., and which claims priority to European
Application 12172854.7 filed in Europe on Jun. 21, 2012. The entire
contents of these applications are hereby incorporated by reference
in their entireties.
FIELD
[0002] The present disclosure relates to determining the topology
of a communication network of an industrial process control system,
such as a substation automation system.
BACKGROUND INFORMATION
[0003] In order to discover and determine the topology of a
communication network, it may be required that network devices
report knowledge of their local topology to a network management
device. Several products exist on the market, such as, for example,
Hirschmann's HiVision, wherein protocols like ARP (ARP: Address
Resolution Protocol), ICMP (ICMP: Internet Control Message
Protocol), or SNMP (SNMP: Simple Network Management Protocol) are
used. These tools operate on layer 3, for example, using IP
addresses (IP: Internet Protocol) of the network devices, and are
not directly aware of layer 2 devices or configurations, such as,
for example, media converters, repeaters, unmanaged bridges or
switches operating on layer 2 only.
[0004] On the link layer, namely on layer 2, the topology of
communication networks may be discovered using the vendor-neutral
Link Layer Discovery Protocol (LLDP, IEEE 802.1AB) or using
vendor-specific protocols such as Microsoft's Link Layer Topology
Discovery (LLTD), the Cisco Discovery Protocol, or any other
vendor-specific protocol. In the LLDP, network devices send through
each of their network interfaces, at a fixed interval, a so-called
Link Layer Discovery Protocol Data Unit (LLDPDU) in the form of an
Ethernet frame, which has its destination MAC address (MAC: Media
Access Control) set to a specific multicast address. Information
gathered with LLDP is stored in the network devices in a management
information database (MIB) and may include system names, port
names, VLAN names, etc. The MIB of the network devices may be
queried with the SNMP in order to discover the network nodes and
establish the topology of a network in which all devices are
LLDP-enabled. The latter prerequisite, however, is not fulfilled in
most automation networks deployed today.
SUMMARY
[0005] An exemplary embodiment of the present disclosure provides a
method for determining the network topology of a communication
network including at least one first network device connected
through at least one network link to at least one neighboring
network device. The at least one first network device and the at
least one neighboring network device are synchronized according to
the IEEE 1588 standard. The exemplary method includes determining,
by each of the at least one first network device, an identity of
the at least one neighboring network device and a communication
delay of the at least one network link, respectively. The exemplary
method also includes collecting, by a network manager, the
respective determined identity and communication delay, and
determining a network topology of the communication network
including a length of the at least one network link therefrom.
[0006] An exemplary embodiment of the present disclosure provides a
network management agent for determining the network topology of a
communication network including at least one first network device.
Each first network device is connected through at least one network
link to at least one neighboring network device. The at least one
first network device and the at least one neighboring network
device are synchronized according to the IEEE 1588 standard. The
network management agent includes a processor configured to, by
executing a computer program tangibly recorded on a non-transitory
computer-readable recording medium of the network management agent,
collect, from each of the at least one first network device, an
identity of the at least one neighboring network device and a
communication delay of the at least one network link, respectively,
and determine the network topology of the communication network
including a length of the at least one network link therefrom.
[0007] An exemplary embodiment of the present disclosure provides a
non-transitory computer-readable recording medium having a computer
program tangibly recorded thereon that, when executed by a
processor of a computer processing device, causes the processor to
carry out a method for determining the network topology of a
communication network including at least one first network device
connected through at least one network link to at least one
neighboring network device. The at least one first network device
and the at least one neighboring network device are synchronized
according to the IEEE 1588 standard. The exemplary method includes
determining, by each of the at least one first network device, an
identity of the at least one neighboring network device and a
communication delay of the at least one network link, respectively.
The exemplary method also includes collecting, by a network
manager, the respective determined identity and communication
delay, and determining a network topology of the communication
network including a length of the at least one network link
therefrom.
BRIEF DESCRIPITION OF THE DRAWINGS
[0008] Additional refinements, advantages and features of the
present disclosure are described in more detail below with
reference to exemplary embodiments illustrated in the drawings, in
which:
[0009] FIG. 1 shows a sample network topology of a communication
network according to an exemplary embodiment of the present
disclosure, and
[0010] FIG. 2 shows an exemplary sequence of steps for determining
the network topology of a communication network.
DETAILED DESCRIPTION
[0011] Exemplary embodiments of the present disclosure provide a
method and a network management agent for determining the topology
of a communication network which is widely deployable and which
includes additional aspects relating to the network topology.
According to an exemplary embodiment, the communication network
includes one or more first network devices, which are each
connected through one or more network links to one or more
neighboring network devices. The one or more first network devices
and the one or more neighboring network devices are synchronized
according to the IEEE 1588 standard entitled "Precision Time
Protocol." Exemplary embodiments of the present disclosure avoid at
least some of the disadvantages of the prior art in communication
network topology determination.
[0012] According to an exemplary embodiment of the present
disclosure, the network topology of a communication network is
determined, where the communication network includes one or more
first network devices each connected through one or more network
links to one or more neighboring network devices or peer devices
includes the following steps. Each of the one or more first network
devices determines an identity of each of the respective
neighboring network devices as well as a communication delay, or
peer delay, between the first network device and each of the
respective neighboring network devices according to the
above-described IEEE 1588 standard. The determined identities of
the respective neighboring network devices and the communication
delays of the respective communication links are collected by a
network manager, and exploited to determine the network topology of
the communication network including a length of the one or more
network links.
[0013] According to an exemplary embodiment the present disclosure,
from the communication delays, additional conclusions can be drawn
regarding some physical, as opposed to purely logical, aspects of
the network topology. For example, the inter-device communication
delays of a deployed network may be converted into distances or
cable lengths and compared to the corresponding intended or design
parameters. Furthermore, excessive communication delays may be
interpreted as being due to unwanted devices in the communication
network that do not adhere to the path delay determination
protocol.
[0014] Exemplary embodiments of the present disclosure take
advantage of the fact that in communication networks synchronized
according to the IEEE 1588 standard, the network devices
synchronize to a reference clock upon receipt of a synchronization
message. In such networks, as the port through which a
synchronization message arrives can vary upon reconfiguration of
the network or change of the master clock, each device regularly
calculates the peer delays on all of its ports. By identifying the
neighboring devices and determining the communication delays to
neighboring network devices, a communication device determines its
local network topology. A network manager ultimately collects these
local network topologies and determines the network topology of the
communication network by reverting to known protocols such as SNMP.
Moreover, an additional parameter describing the network topology
is provided because the communication delay between the network
devices is determined. This allows for a check to be made if the
network corresponds to the engineering drawings and can determine
if the physical distance has been respected and if unauthorized
devices have been inserted.
[0015] In accordance with an exemplary embodiment, the one or more
first network devices transmit a peer delay request message to the
one or more neighboring network devices. The peer delay request
message is received by the one or more neighboring network devices
and triggers the neighboring network devices to transmit a peer
delay response message to the one or more first network devices.
The peer delay response message is received by the one or more
first network devices and enables the latter to determine the one
or more communication delays between the one or more first network
devices and the one or more neighboring network devices as provided
for in IEEE 1588. In other words, the network devices send
spontaneously to all devices to which they are connected a peer
delay request message to which the peer responds with a peer delay
response message containing its identity and a time stamp
indicating the time difference between the instant the device
received the peer delay request and responded with the peer delay
response message and possibly the absolute time as seen on the
local clock of the peer, as well. Thus, the sender of the peer
delay request can determine the identity of and the line
propagation delay to all its peers and thus generate network
topology information. The IEEE 1588 standard is becoming a widely
available standard in network devices, and the only addition
required is the ability to report the identity of the peer and the
value of the peer delay to network management.
[0016] In accordance with an exemplary embodiment, a broadcast
device is configured to broadcast a synchronization message to the
one or more first network devices enabling the one or more first
network devices to receive the synchronization message via a first
port or network interface, and triggering the one or more first
network devices to transmit the synchronization message via one or
more second ports or network interfaces to neighboring nodes.
Accordingly, the synchronization message is broadcasted to network
devices not directly connected to the broadcast device. The
synchronization message may then be exploited in determining the
communication delays, for example, in connection with response
messages transmitted by the neighboring nodes to the one or more
first network devices.
[0017] In accordance with an exemplary embodiment, a graphical
network diagram is generated showing the actual network topology of
the communication network. The actual network topology of the
communication network can thus be easily verified.
[0018] In accordance with an exemplary embodiment, a graphical
network diagram showing the design of the network topology of the
communication network is updated. For example, updating the
graphical network diagram may include marking missing or erroneous
network links. Accordingly, the actual network topology of the
communication network including idle links can thus be easily
compared to a designed network topology according to design
requirements.
[0019] In accordance with an exemplary embodiment, a network
management agent is configured to collect through, for example,
SNMP (SNMP: Simple Network Management Protocol) from a MIB (MIB:
Management Information Base) stored in the one or more first
network device, the one or more communication delay together with
the MAC address (MAC: Media Access Control) of the one or more
first network device. By collecting the MAC address, the interfaces
of the network devices are uniquely identified. Moreover, the
communication delay of the network links provide additional
information about the network topology of the communication
network. As data is stored in widely deployed MIB and collected to
the widely available SNMP, collection of the data is widely
deployable in various communication networks.
[0020] Exemplary embodiments of the present disclosure relate to a
network management agent, device, or module for determining the
network topology of a communication network based on at least one
neighbor network or end device identity and corresponding network
link communication delay collected from, determined by, and stored
in a Management Information Base of, at least one first network
device of the communication network. Neighbor identities and
communication delays are preferably determined by reverting to the
IEEE 1588 standard entitled "Precision Time Protocol."
[0021] Exemplary embodiments of the present disclosure are
described hereinafter in terms of the functions performed by the
network management agent, device or module, which may be
collectively referred to as devices of the present disclosure. It
is to be understood that the functions of these devices as
described hereinafter are each respectively implemented in one or
more computer processing devices configured to individually and/or
collectively perform the functions of the network management
agents, devices or modules. Such computer processing devices may be
a personal computer or server computer each appropriately
programmed to carry out the respective functions of the devices as
described herein. The computer processing devices each include a
processor and a non-transitory computer-readable recording medium,
which is a non-volatile memory such as a ROM, hard disk drive,
flash memory, optical memory, etc. The non-transitory
computer-readable recording medium has tangibly recorded thereon a
computer program and/or computer-readable instructions which, when
executed by the processor of the computer processing device, causes
the processor to perform the operative functions of the devices as
described herein. The processor may be a general-purpose processor
such as those produced by Intel.RTM. or AMD.RTM., for example.
Alternatively, the processor may be an application specific
processor which is specifically designed for the computer(s) of the
respective device(s).
[0022] FIG. 1 shows a sample network topology of a communication
network 1 including several network devices 10, 20, 30, 40, 50 and
network end devices 21, 41, 42, 51, 52. In particular, the
communication network 1 may be an Ethernet based communication
network, wherein data packets are transported by network devices
10, 20, 30, 40, 50, such as, for example, bridges, routers,
servers, computers, etc., which are connected through network links
11, 12, 13, 14, 15, 16. The network links may include in particular
Ethernet network cables or fiber optical cables. The communication
network 1 may be designed to be used in an industrial automation
system.
[0023] The network devices 10, 20, 30, 40, 50 are designed to
receive and forward network traffic, and they may themselves
consume parts of the received traffic. For example, a bridge
according to the IEEE 802.1D standard is designed to receive and
transmit network traffic on a layer 2, i.e. link layer, of the
communication network 1. As bridges operate on layer 2 only, they
are not discoverable on layer 3, such that, for example, an
application running on a server at layer 3 is not able to discover
the layer 2 topology of the communication network 1. However, layer
2 topology is required in order to verify that the communication
network 1 has been properly installed and configured, for example,
or that the communication network 1 is operating without errors or
failures.
[0024] As shown in FIG. 1, the communication network 1 includes a
broadcast device 21, which may include a grandmaster with a
grandmaster clock MC according to the IEEE 1588 standard or a
similar protocol, such as, for example, IEEE 802.1AS. As indicated
in FIG. 1, the broadcast device 21 may be connected to a GPS
receiver (GPS: Global Positioning System), such that the
grandmaster clock MC may be synchronized with an accurate time from
one or more GPS satellites, for example. However, the grandmaster
clock MC may receive a precise time through any other suitable
device, in particular with a high-stability oscillator.
[0025] The broadcast device 21 broadcasts a synchronization message
2, which is received by network devices 10, 20, 30, 40, 50 of the
communication network 1 and all end devices 41, 42, 51, 52. The
network devices 10, 20, 30, 40, 50 and the end devices are
configured according to the IEEE 1588 standard, for example.
Accordingly, the network devices 10, 20, 30, 40, 50 may include a
transparent clock TC and may be configured to forward the
synchronization message 2 received on one of its network interfaces
to all its other network interfaces. According to the IEEE 1588
standard, for example, a correction is computed which is sent in
the same synchronization message 2' or in a subsequent
synchronization message 2'' (one-step or two-step synchronization).
Hence, the synchronization message 2 is broadcasted from the
grandmaster device 21 including the master clock MC to the network
devices 10, 20, 30, 40, 50, which comprise transparent clocks TC,
of the communication network 1.
[0026] To compute the time correction due to the link delay, all
network devices of the communication network 1 may be configured to
transmit one or more peer delay request messages 3 through all
their network interfaces, which are received by one or more peer
neighboring devices, for instance device 10 sends such peer delay
request to network devices 20, 30, 40 and to the end device 21. The
device receiving the peer delay request message 3 can be configured
to answer immediately with a peer delay response message 4 back to
the originator of the peer delay request, in this case the network
device 10.
[0027] The network devices 10 computes the communication delays
d12, d13, d14 to its neighbors by time-stamping the peer delay
request message 3 and receiving the peer delay response message 4
which also contains the sending time. For example, the peer delay
request message 3 may include a first timestamp indicating the time
when the peer delay request message 3 was sent. The peer delay
response message 4 may further include a second timestamp
indicating the time difference between the reception of message 3
and the sending of message 4, which is called the latency. The
originator records the time at which the peer response message 4
was returned. Hence, the communication delays d12, d13, d14 may be
computed by subtraction of the first timestamp from the second
timestamp and subtracting the received latency. The computation of
communication delays may also be performed by the end devices 41,
42, 51, 52, which comprise ordinary clocks OC, and by the broadcast
device 21, which includes the master clock MC.
[0028] The communication delays d12, d13, d14 between the network
devices 10, 20, 30, 40, 50 are a function of the cable length.
Accordingly, on the basis of the computed communication delays d12,
d13, d14, the cable length between network devices 10, 20, 30, 40,
50 may be computed. Moreover, network devices which do not conform
to, for example, the IEEE 1588 standard may be detected, as such
network devices introduce a significant additional communication
delay, which is well in excess of any expected cable propagation
delays. The wave propagation speed s on a network cable may range
from 0.59 c to 0.77 c (c: speed of light). Accordingly, the delay
on a network cable segment of the length of 1 m may range from 4.3
ns to 5.6 ns. On the other hand, the switching delay of network
devices such as network switches or bridges may be in the range of
10-40 .mu.s, or even higher, such that the presence of such devices
that are not equipped with IEEE 1588 TCs can be easily detected.
Bridging devices not equipped for the IEEE 1588 do not respond at
all and are easily detected by a timeout.
[0029] Messages between the network devices 10, 20, 30, 40, 50 may
be sent using multicast messaging or unicast transmission. The
messages may conform to the IEEE 1588 standard, or any other
similar standard. In case the messages are transmitted on layer 3,
the messages may be transmitted using IP packets. For example, UDP
packets may be transmitted (UDP: User Datagram Protocol). Messages
may also be transmitted on layer 2 through encapsulation in IEEE
802.3 Ethernet, or any other layer 2 protocol.
[0030] The determined communication delays d12, d13, d14 between
the network devices 10, 20, 30, 40, 50 may be stored in a
management information base (MIB) or in any other database. The MIB
may be stored on the network devices 10, 20, 30, 40, 50 or one of
the end devices 21, 41, 42, 51, 52. Hence, each network device 10,
20, 30, 40, 50 may have stored thereon the local topology to its
neighboring devices. For example, network device 10 according to
FIG. 1 may have stored the delay d12 through network link 12 to the
network device with numeral 20, the delay d14 through network link
14 to the network device with numeral 40, the delay d13 through
network link 13 to the network device with numeral 30, and the
delay d1M through network link 1M to the grandmaster device 21.
[0031] The data stored in the MIB of the network device with label
10, for example, may include the MAC address (MAC: Media Access
Control) of the network device with label 10 and the MAC address of
the neighboring network devices 20, 30, 40 together with the
determined communication delays d12, d13, d14 to the neighboring
network devices. As such, the MIB includes the local network
topology of the network device with label 10, namely the
information about network links 12, 13, 14 and neighboring network
devices 20, 30, 40 as well as the information about a distance or
communication delay between the network device with label 10 and
the neighboring network devices 20, 30, 40. [0032] A network
management agent A may be configured to collect the MIB or any
other database stored in the network devices 10, 20, 30, 40, 50.
For example, data of the MIB of the network devices 10, 20, 30, 40,
50 may be collected through the SNMP protocol (SNMP: Simple Network
Management Protocol). Collection of the MIB or the database stored
in the network devices 10, 20, 30, 40, 50 may be performed through
any other protocol, such as, for example, IEC 61850, which is a
widely-used standard for electrical substation automation
systems.
[0033] Accordingly, the network management agent A may collect the
information about network links 12, 13, 14 between network devices
10, 20, 30, 40, 50 as well as the distance or communication delay
d12, d13, d14.
[0034] The network management agent A may be configured to generate
a graphical network diagram showing the actual topology of the
communication network. The network diagram does not necessarily
reflect the geographical location of the network devices. However,
the distances or communication delays between the network devices
may well be shown graphically.
[0035] The network management agent A may be configured to update a
graphical network diagram showing the design of the network
topology of the communication network. Hence, when engineering a
communication network, the network configuration may be designed
according to design requirements, which may include geographical
allocation of the network devices 10, 20, 30, 40, 50, e.g. ordered
by bays, cabinets, etc., wherein data may be coded in a wiring
diagram or in an SCD file according to the IEC 61850 standard.
Knowing the physical dimensions, an engineering tool, which is an
example of the above-described computer processing device, can
predict the approximate values of the link delays. The
communication network may be commissioned according to the design
requirements. In a graphical network diagram of the commissioned
communication network, those network links are graphically
indicated which have been wrongly commissioned, which are
erroneous/missing or which show a communication delay exceeding a
certain value. This helps detect devices which are not working
properly, devices of the wrong type or unwanted devices that could
ruin the synchronization.
[0036] FIG. 2 shows schematically exemplary steps for the
determination of the network topology of a communication network 1
according to an exemplary embodiment of the present disclosure. In
step S1, a synchronization message is broadcasted. In step S2, the
synchronization message 2 is received by the one or more first
network devices 10 on one of its network interfaces. In step S3,
the communication delays d12, d13, d14 between the one or more
first network devices 10 and the one or more neighboring network
devices 20, 30, 40 is determined. In step S4, the determined one or
more communication delays d12, d13, d14 are collected, for example,
through SNMP from a MIB stored in the one or more first network
devices 10. In step S5, the one or more communication delays d12,
d13, d14 are used to determine the network topology of the
communication network 1.
[0037] In step S21, the synchronization message 2 triggers
transmission of a peer delay request message 3 to the one or more
neighboring network devices 20, 30, 40. In step S22, the peer delay
request message 3 triggers transmission of a peer delay response
message 4 to the one or more first network devices 10. In step S3,
the peer delay response message 4 enables determination or
computation of the one or more communication delays d12, d13, d14
between the one or more first network devices 10 and the one or
more neighboring network devices 20, 30, 40.
[0038] In step S20, the synchronization message 2 is received on
one of the network interfaces of the one or more first network
devices 10 and the synchronization message is transmitted to one or
more of the other network interfaces.
[0039] In step S51, a graphical network diagram showing the actual
network topology of the communication network is generated. In step
S52, a graphical network diagram showing the design of the network
topology of the communication network is updated.
[0040] It will be appreciated by those skilled in the art that the
present invention can be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. The
presently disclosed embodiments are therefore considered in all
respects to be illustrative and not restricted. The scope of the
invention is indicated by the appended claims rather than the
foregoing description and all changes that come within the meaning
and range and equivalence thereof are intended to be embraced
therein.
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