CN107135045A - The transformer station's adaptive network and its clock synchronous safety method detected based on difference - Google Patents
The transformer station's adaptive network and its clock synchronous safety method detected based on difference Download PDFInfo
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- CN107135045A CN107135045A CN201710342224.4A CN201710342224A CN107135045A CN 107135045 A CN107135045 A CN 107135045A CN 201710342224 A CN201710342224 A CN 201710342224A CN 107135045 A CN107135045 A CN 107135045A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
- H04J3/0647—Synchronisation among TDM nodes
- H04J3/065—Synchronisation among TDM nodes using timestamps
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/32—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
- H04L9/3297—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials involving time stamps, e.g. generation of time stamps
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q2011/0079—Operation or maintenance aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q2011/0079—Operation or maintenance aspects
- H04Q2011/0083—Testing; Monitoring
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- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Computer Security & Cryptography (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Small-Scale Networks (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
Abstract
The invention belongs to intelligent substation technical field of network security, more particularly to a kind of transformer station's adaptive network detected based on difference and its clock synchronous safety method.Network includes：Optical network unit ONU, synchronous optical line terminal OLT and EPON protocol processors；Each ONU has two interfaces to have identical state forever, using the redundant configuration of active and standby link；EPON protocol processors are communicated by Multi-point Control Protocol with ONU.Method includes：Timestamp is passed to each ONU by EPON protocol processors；Whether two interfaces that OLT compares ONU receive the uniformity for the synchronized timestamp that message and message are carried within the regulation time difference, if it is not, then there is security threat, pair when do not adjust；If so, then OLT detects whether round-trip delay RTT value differences values exceedes defined threshold value, if so, then there is security threat, pair when do not adjust；If not less than threshold value, completing ONU registrations and starting proper communication.
Description
Technical field
The invention belongs to intelligent substation technical field of network security, more particularly to a kind of transformer station detected based on difference
Adaptive network and its clock synchronous safety method.
Background technology
Intelligent substation adaptive network physical arrangement and EPON (Ethernet Passive Optical Network,
Ethernet passive optical network) it is identical, and the thought of Tag switching is used in core switch, realize GOOSE, SV and MMS tri-
Net unification.In order to improve network reliability, dual star topology (A, B) network architecture is established, A, B network constitute main-standby mode.Newly
Stable operation of the reliability of type intelligent substation adaptive network to whole intelligent substation plays an important roll, when especially
Between synchronization system it is most important.IEEE1588 standards are that Novel intelligent substation system defines accurate clock synchronization protocol PTP,
And realize the time synchronized of transformer station's submicrosecond precision.But, if time synchronized failure, or it is destroyed, be particularly
Equipment in system is implanted after Rogue program, once Rogue program is performed and starts destruction clock synchronization, will be made across interval
Protect (transformer, bus) out of service because of asynchronous sampling, or even misoperation, so as to cause substation fault.
The content of the invention
In order to improve the security of substation network clock, solve Novel intelligent substation communication setting network and attacked
When defense mechanism imperfection, tackle man-in-the-middle attack situation, the present invention provide it is a kind of based on difference detect transformer station it is adaptive
Answer network and its clock synchronous safety method.
Network includes：Optical network unit ONU, synchronous optical line terminal OLT and EPON protocol processors；Wherein, Mei Geguang
NE ONU interface module has two interfaces to have identical state forever, and substation network is superfluous using active and standby link
Remaining configuration mode；Each optical network unit ONU can track the clock source of synchronous optical line terminal OLT；EPON protocol processors
Communicated by internal Multi-point Control Protocol MPCP with each optical network unit ONU.
Method includes：
Timestamp is passed to each optical network unit by step 1, the EPON protocol processors of intelligent substation network
ONU；
Whether two interfaces that step 2, synchronous optical line terminal OLT compare optical network unit ONU are received within the regulation time difference
The message arrived, if it is not, there is security threat when then judging pair, and gives a warning, and adjusted when not taking the time pair；If so, then
Perform step 3；
Coming and going in the message that step 3, two interfaces of synchronous optical line terminal OLT detection optical network unit ONU are received
, if two round-trip delay RTT value differences values exceed defined threshold value, there is security threat during judgement pair, concurrently in time delay RTT values
Go out warning, and adjusted when not taking the time pair；If two round-trip delay RTT value differences values are completed not less than defined threshold value
Optical network unit ONU is registered and starts normal pass with optical line terminal OLT.
The registration process of the optical network unit ONU includes：
Step 301, optical line terminal OLT send registration and find that frame is broadcast to each optical network unit at a time interval
ONU, its destination address is broadcast logical link indicia LLID, between this frame is included at the beginning of discovery window, the big rootlet of window
Determined according to the farthest optical network unit ONU of distance in system；
Step 302, new optical network unit ONU receive registration and found after frame, and this is adjusted according to the clock label field of reception
Ground clock, then sends registration request frame, while optical network unit ONU within the defined windowing time to optical line terminal OLT
Delay measurements are carried out by Multi-point Control Protocol MPCP messages；
The broadcast transmission registration control after a window receives only one registration request frame of step 303, optical line terminal OLT
Frame processed gives the optical network unit ONU, be included as in the control frame optical network unit ONU distribution logical links label L LID and
Lock in time, while logical links label L LID and optical network unit ONU MAC Address are associated together；
Step 304, optical line terminal OLT then send registed authorization frame to optical network unit ONU, so as to optical line terminal
OLT dispatch the up transmission of optical network unit ONU time slot, at the same time Multi-point Control Protocol MPCP rangings complete, calculating it is past
Returning time delay RTT values will also be updated by optical network unit ONU for the time；
Step 305, new optical network unit ONU are received after registed authorization frame, and newly assigned logical links label L LID is replaced
Original logical links label L LID is changed, while sending accreditation verification frame to optical line terminal OLT；
Step 306, optical line terminal OLT are received after accreditation verification frame, refresh the logic chain road sign of the optical network unit ONU
Remember LLID, complete the automatic discovery procedure of optical network unit ONU.
The protocol processor is stabbed by internal Multi-point Control Protocol MPCP messages passing time.
The timestamp is the timestamp based on IEEE1588 agreements.
The beneficial effects of the present invention are：
By the analysis to EPON clock synchronization systems in intelligent substation, for man-in-the-middle attack, propose a kind of new
ONU sides double-PON port difference testing mechanisms takes precautions against this challenge model, and link delay time emulation is carried out to the model proposed
Measurement alerts and terminated time renewal to verify that increased testing mechanism can be provided successfully to attack.
Examined by contrasting the RTT under the round trip delay time RTT under normal condition, man-in-the-middle attack state and adding difference
The RTT values of survey mechanism, show that mechanism proposed by the present invention can provide alarm to internuncial attack, and in ONU side not mistunings
Whole clock, strengthens the robustness of novel transformer substation network timing synchronization systems.
Examined by contrasting the RTT under the round trip delay time RTT under normal condition, man-in-the-middle attack state and adding difference
The RTT values of survey mechanism, show the ONU sides testing mechanism of the present invention successfully can alert to man-in-the-middle attack, terminate ONU sides
Time updates, and strengthens the robustness and security of novel transformer substation network timing synchronization systems.
Brief description of the drawings
Fig. 1 is normal link RTT schematic diagrames.
Fig. 2 is the RTT schematic diagrames of man-in-the-middle attack.
Fig. 3 is the RTT design sketch after addition ONU difference testing mechanisms.
Embodiment
Below in conjunction with the accompanying drawings, embodiment is elaborated.
The present invention introduces passive optical network technique PON on the basis of intelligent substation network, sets up topological structure letter
Single, reliable double star network structure, PON up-downgoing data transfer uses single fiber wavelength-division multiplex technique, can largely subtract
The complexity of few transformer station fiber optic network, further improves the reliability of network；Substation communication network based on PTN interchangers
In, for the reliability of the clock network that further improves transformer station, using Parallel Redundancy Protocol (PRP) mode of standard, often
Individual ONU interface modules have two interfaces to have identical state forever, and substation network uses the redundant configuration side of active and standby network
Formula, when PRP is run, the highest master clock of clock source connection is connected respectively on active and standby network core interchanger, when primary
It can be seamlessly switched on standby clock device during clock plant failure, the clock sync message that master clock is sent is selected in active and standby net
Two-way is concurrent on network, active release digging soil formula；Novel intelligent substation EPON system is the system of a time synchronized, each
ONU can track OLT clock source.ONU reach the standard grade registration process be exactly time synchronized process.EPON protocol processors pass through
Internal MPCP (Multi-Point Control Protocol, Multi-point Control Protocol) message passes to IEEE1588 timestamps
Each ONU, ONU receive 1588 timestamp post-compensation round-trip delay RTT (Round-Trip Time), when generating the 1588 of ONU
Between stab, the timestamp is synchronous with 1588 clock sources.
ONU of the present invention registration process：
(1) (being traditionally arranged to be 1s) transmission registration finds that frame is broadcast to each ONU to OLT at certain intervals, its destination address
For broadcast LLID (complete zero), between this frame is included at the beginning of discovery window, while determining window according to the farthest ONU of distance in system
Mouth size (general 20 kilometers are 250 microseconds).
(2) new ONU receives registration and found after frame, and local clock is adjusted according to the clock label field of reception, then in rule
Registration request frame is sent to OLT in the fixed windowing time, while ONU receives MPCP (Multi-Point Control
Protocol, Multi-point Control Protocol) message delay measurements.
(3) OLT is after a window receives only one registration request frame, and OLT broadcast transmissions registration control frame is given should
LLID and the lock in time of ONU distribution are included as in ONU, the control frame, while LLID and ONU MAC Address are associated in
Together.
(4) OLT then sends registed authorization frame (MPCP rangings are completed, and calculate RTT) to ONU, and now sending is sent out for ONU
Bandwidth authorization message is sent, so that OLT dispatches the time slot of the up transmissions of ONU, then this MPCP ranging simultaneously is completed, the RTT values of calculating
Also it will be updated by ONU for the time.
(5) new ONU is received after registed authorization frame, and newly assigned LLID is replaced to original LLID, is noted while being sent to OLT
Volume acknowledgement frame.
(6) OLT is received after accreditation verification frame, refreshes the LLID of the ONU, then ONU whole automatic discovery procedure is just
Complete, proper communication can be started between ONU and OLT.
The present invention uses PRP Parallel Redundancy Protocol renewal time information：
Each equipment has two PON mouthfuls of transmitted in parallel data, and selectivity is received, while having active and standby net to increase network
Reliability.In principle, 1588 timestamps that ONU synchronously gets off from double-PON port are essentially identical (error are in tens nanoseconds).When
In the case of two PON mouthfuls of optical links are all normal, as long as ONU arbitrarily tracking 1588 timestamp all the way.After the completion of registration
Normal condition under, ONU receives MPCP messages every time can all update local zone time and monitor situation of change, and OLT is received every time
MPCP messages can all update and monitor RTT change.The OLT that ONU is carried according to MPCP messages timestamp information, RTT values with
And the local timers of ONU can calculate and update 1588 times.
Analyze man-in-the-middle attack mode：
There is the timestamp information that intermediate equipment obtains MPCP messages OLT at the middle and upper levels, and OLT clock sections in man-in-the-middle attack
Point essential information (IP, MAC etc.), and the ONU equipment of subordinate is transmitted to, at normal pair in the cycle, intermediate equipment intercepts and captures OLT
Time synchronized MPCP messages between equipment and ONU equipment, go-between's equipment for OLT equivalent to from clock status, under
Layer ONU is equivalent to master clock state.
Man-in-the-middle attack node can be sent to ONU temporal information value by changing, and carry out any change and send MPCP messages
To ONU time, and then manipulate link RTT value, this also imply that attacker can arbitrarily manipulate ONU nodes it is real-time when
Clock, the ONU clock nodes equipment can be made progressively to deviate the real-time clocks of OLT node devices can not without being found failure, failure
It is found also be switched standby clock network, it is inconsistent to be likely to result in active and standby network instruction, in turn results in clock more
New confusion.
The present invention increases difference testing mechanism in ONU sides：
The first step：Detect that MPCP messages receive the time difference.Each ONU equipment has two PON mouthfuls parallel, and comparing ONU twoports is
No within the regulation time difference (settable) is while the MPCP messages received, if main PON mouthfuls receives MPCP messages and prepare renewal RTT
During value calibration local zone time, standby PON mouthfuls does not receive what MPCP messages or the message received were carried within the regulation time difference
1588 synchronized timestamps are inconsistent, then there is security threat during judgement pair, and give a warning, and adjusted when not taking the time pair.
Second step：Detect the RTT values in MPCP messages.After first step detection, if ONU twoports are being provided in the time difference simultaneously
The MPCP messages received, increased testing mechanism then contrasts the RTT values in ONU double-PON port messages, under normal circumstances double-PON port
The time delay of link only had for tens nanoseconds, when two RTT value differences values exceed defined threshold value (settable), was deposited during judgement pair
Adjusted when in security threat, and giving a warning, and not taking the time pair.
The testing mechanism of the present invention is emulated：
(1) when being added without detection
1. to OLT and ONU pair when build model, normal link RTT values such as Fig. 1 is measured under normal running status
Shown, in figure, abscissa is time shaft, and ordinate is time delay, set threshold value for 200 nanoseconds situation under, link when
Prolong and do not produce alarm in normal scope, ONU sides carry out time renewal.
2. in the state of major network all the way has man-in-the-middle attack, shown in OLT sidelinks major network pair when be normal nothing
Link failure, would not also be switched to another road time system, go-between's change send MPCP messages to lower floor ONU when
Between and round-trip delay RTT values, and cause clock pair when failure.More than nanosecond also will not as shown in Fig. 2 time delay increases to 200
Link failure and alarm are produced, and ONU sides carry out time renewal, make system failure risk.
(2) when adding ONU side testing mechanisms
Whether detection ONU sides double-PON port receives MPCP messages simultaneously within the regulation time difference, if having met, then detects
Whether the RTT differences that double-PON port is respectively received meet the detection threshold of setting.As shown in figure 3, the difference for the RTT that double-PON port is received
It is excessive, not within normal threshold value (it is assumed that being set to for 100 nanoseconds), then alarming mechanism is produced, ONU sides terminate the time more
Newly.
Conclusion
Examined by contrasting the RTT under the round trip delay time RTT under normal condition, man-in-the-middle attack state and adding difference
The RTT values of survey mechanism, show the ONU sides testing mechanism of the present invention successfully can alert to man-in-the-middle attack, terminate ONU sides
Time updates, and strengthens the robustness of novel transformer substation network timing synchronization systems.
Above-described embodiment is only the present invention preferably embodiment, but protection scope of the present invention is not limited to
This, any one skilled in the art the invention discloses technical scope in, the change that can readily occur in or replace
Change, should all be included within the scope of the present invention.Therefore, protection scope of the present invention should be with the protection model of claim
Enclose and be defined.
Claims (5)
1. a kind of substation communication network detected based on interpolation, it is characterised in that including：Optical network unit ONU, synchronous light
Road terminal OLT and EPON protocol processor；Wherein, the interface module of each optical network unit ONU has two interfaces to have forever
Identical state, substation network uses the redundant configuration mode of active and standby link；Each optical network unit ONU can be tracked together
Walk the clock source of optical line terminal OLT；EPON protocol processors pass through internal Multi-point Control Protocol MPCP and each optical-fiber network list
First ONU is communicated.
2. a kind of time synchronized safety method based on transformer station's adaptive network described in claim 1, it is characterised in that bag
Include：
Timestamp is passed to each optical network unit ONU by step 1, the EPON protocol processors of intelligent substation network；
What whether two interfaces that step 2, synchronous optical line terminal OLT compare optical network unit ONU received within the regulation time difference
Message, if it is not, there is security threat when then judging pair, and gives a warning, and adjusted when not taking the time pair；If so, then performing
Step 3；
Round-trip delay in the message that step 3, two interfaces of synchronous optical line terminal OLT detection optical network unit ONU are received
, if two round-trip delay RTT value differences values exceed defined threshold value, there is security threat, concurrent responding during judgement pair in RTT values
Accuse, and adjusted when not taking the time pair；If two round-trip delay RTT value differences values are not less than defined threshold value, light net is completed
Network unit ONU is registered and starts proper communication with optical line terminal OLT.
3. method according to claim 2, it is characterised in that the registration process of the optical network unit ONU includes：
Step 301, optical line terminal OLT send registration and find that frame is broadcast to each optical network unit ONU at a time interval,
Its destination address is broadcast logical link indicia LLID, between this frame is comprising finding at the beginning of window, and the size of window is according to being
Distance farthest optical network unit ONU is determined in system；
Step 302, new optical network unit ONU receive registration and found after frame, when adjusting local according to the clock label field of reception
Clock, then sends registration request frame, while optical network unit ONU is received within the defined windowing time to optical line terminal OLT
The delay measurements of Multi-point Control Protocol MPCP messages；
Step 303, the optical line terminal OLT broadcast transmission after a window receives only one registration request frame register control frame
The optical network unit ONU is given, logical links label L LID and the synchronization of optical network unit ONU distribution are included as in the control frame
Time, while logical links label L LID and optical network unit ONU MAC Address are associated together；
Step 304, optical line terminal OLT then send registed authorization frame to optical network unit ONU, so as to optical line terminal OLT
Dispatch the up transmission of optical network unit ONU time slot, at the same time Multi-point Control Protocol MPCP rangings complete, calculating it is round when
Prolonging RTT values will also be updated by optical network unit ONU for the time；
Step 305, new optical network unit ONU are received after registed authorization frame, and newly assigned logical links label L LID is replaced into former
The logical links label L LID come, while sending accreditation verification frame to optical line terminal OLT；
Step 306, optical line terminal OLT are received after accreditation verification frame, refresh the logical links mark of the optical network unit ONU
LLID, completes the automatic discovery procedure of optical network unit ONU.
4. method according to claim 2, it is characterised in that the EPON protocol processors pass through internal Multi-point Control Protocol
MPCP messages passing time is stabbed.
5. method according to claim 2, it is characterised in that the timestamp is the timestamp based on IEEE1588 agreements.
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| CN113727218A (en) * | 2020-05-25 | 2021-11-30 | 中国电信股份有限公司 | Method for setting length of static window and related equipment |
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| CN107135045B (en) | 2019-01-25 |
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