CN104753584B - EPON backbone's optical link protection system and its quick method switched of realization - Google Patents
EPON backbone's optical link protection system and its quick method switched of realization Download PDFInfo
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Abstract
The invention discloses a kind of EPON backbone's optical link protection system and its quick method switched of realization, it is related to passive optical network technique field, the method includes OLT A by Lmax‑a、Teqd‑a, PLOu sent to OLT B；OLT B are according to Lmax‑bAnd Lmax‑a, W is setsize, and obtain the balanced time delay on the primary optical link of ONU line information tables and each ONU；When OLT B detect optical module and have uplink optical signal, the bandwidth authorization message of ONUi is obtained from OLT A, calculate balanced time delays of the ONUi on standby optical link；OLT B calculate the difference of ONUi balanced time delays on standby and primary optical link；OLT A difference renewal ONU line information tables, and send to corresponding ONU；OLT B detect triggering protection criteria, directly enable bandwidth authorizing table；From POPUP states automatically into working condition, the bandwidth authorizing to OLT B responds all of ONU in system, sends uplink service.
Description
Technical field
It is specifically a kind of EPON backbone optical link protection system the present invention relates to passive optical network technique field
System and its quick method switched of realization.
Background technology
PON (Passive Optical Network, EPON) technology is the broadband optical access skill based on optical fiber
Art, optical network system is by OLT (Optical Line Terminal, optical line terminal), ODN (Optical Distribution
Network, Optical Distribution Network) and ONU (Optical Network Unit, optical network unit) compositions, because PON system has
The many merits such as high bandwidth, high efficiency, large coverage, user interface be abundant, most of operators realize connecing using the technology
Enter that network service is broadband, synthesization transformation, be laid out extensively, the substantial amounts of Consumer's Experience of acquisition.In passive optical network
When use optical link protection to provide the reliability of optical link, to make standby optical link normally continue the former work of failure
It is operated as optical link, it is necessary to accurately be measured optical link parameter in standby optical link.
PON system is in the upstream direction multipoint-to-point network structure, and different ONU use TDMA (Time Division
Multiple Access, time division multiple acess) access way.Because the distance of ONU to OLT is different, the data of each ONU are flowed through
After crossing the Optical Fiber Transmission of different length, different time delays can be produced；Be additionally, since environment temperature change and device it is aging,
Transmission delay also changes constantly.Therefore, the data flow of different ONU enters the common optical fiber of light distributor, if being not added with control
System, is possible to collide and overlaps.So, PON system needs to be measured the distance of each ONU and OLT, control
Each ONU sends the moment of upstream data, it is to avoid data collision, the key message is exactly the EqD (Equalization of ONU
Delay, balanced time delay).
It is normally to provide service, it is necessary to obtain the status information of ONU when reserve link turns into active link, optical link shape
Each ONU equilibriums time delay in state, particularly link.And must be after the switching of primary, spare optical link under these information, general scenario
Can just be measured on work optical link by the OLT that works, obtained, it is necessary to interrupt the business service of all users, what is mourned in silence
OLT time delays balanced with the optical link parameter of each ONU could be measured under situation.This cause passive optical network to
The interrupting time of family business service increases, so as to the data safety for causing user is not to be fully ensured.
In addition, in EPON, the status change of ONU is controllable by OLT and optical link situation.Traditional ONU
Status change it is shown in Figure 1, when occur optical link switch when, ONU can detect downlink optical signal loss, from working condition
(O5) POPUP states (O6) are entered into.ONU determined by T02 timers in holding time for O6 states, the time-out of T02 timers
Time is 100ms, and only ONU is delayed when getting equilibrium and can just enter into working condition (O5).This needs the work OLT to carry out soon
Speed range finding and the balanced time delay for quickly sending each ONU.And when online ONU is more in system, these actions are likely to not
Can be completed before T02 timer expiries, so indivedual ONU can be made to go offline.And, it is necessary to experience finds ONU again after ONU goes offline
Re-registered to ONU, authorize whole status change process, the business transmission of other ONU of optical link can be had a strong impact on, so that seriously
Influence the service ability to user.
The content of the invention
For defect present in prior art, it is an object of the invention to provide a kind of EPON backbone's optical link
Protection system and its quick method switched of realization, the present invention can quickly be switched to standby optical link, fast quick-recovery user
Business service, the data safety of user can be ensured, improve the stability of the service ability and system to user.
To achieve the above objectives, the present invention is adopted the technical scheme that：The present invention provides a kind of EPON backbone light
Link protection system, the system includes primary optical line terminal OLT-A, standby optical line terminal OLT-B and multiple optical-fiber network lists
First ONU, each ONU pass through 2：N optical branching devices are connected with OLT-A, OLT-B respectively；OLT-A sets most primary optical link
Big fiber distance difference Lmax-a, in this Lmax-aThe zero distance equilibrium time delay T of lower useeqd-a, ONU line information tables and ascending
Reason layer expense PLOu is sent to OLT-B；The maximum fiber range difference L that OLT-B is set according to standby optical linkmax-bAnd Lmax-a,
Detection window size W is setsize；OLT-B obtain on the primary optical link of ONU line information tables and each ONU it is balanced when
Prolong；When OLT-B detects optical module and has uplink optical signal, an online ONU is selected from ONU line information tables, this is online
ONU is set to ONUi；OLT-B obtains the bandwidth authorization message of ONUi from OLT-A, when calculating loops of the ONUi on standby optical link
Prolong RTDi-B, and then by RTDi-BCalculate balanced time delays of the ONUi on standby optical link；OLT-B calculates ONUi in standby light
The difference of the balanced time delay of balanced time delay on link with ONUi on primary optical link, and the difference is sent to OLT-A；
The OLT-A balanced time delays of each ONU on standby optical link in difference renewal ONU line information tables, and each ONU is existed
Balanced time delay on standby optical link is sent to corresponding ONU；OLT-B detects triggering protection criteria, directly enables bandwidth and awards
Power table；From POPUP states automatically into working condition, the bandwidth authorizing to OLT-B responds all of ONU in system,
Send uplink service.
The present invention also provides a kind of EPON backbone's optical link protection system and realizes the quick method switched, the method
Comprise the following steps：The maximum fiber range difference L that step S1.OLT-A sets primary optical linkmax-a, in this Lmax-aLower use
Zero distance equilibrium time delay Teqd-a, ONU line information tables and upstream physical layer expense PLOu sent to OLT-B；Step
The maximum fiber range difference L that S2.OLT-B is set according to standby optical linkmax-bAnd Lmax-a, detection window size W is setsize；
Step S3.OLT-B obtains the balanced time delay on the primary optical link of ONU line information tables and each ONU；Step S4.OLT-B
When detecting optical module and having uplink optical signal, an online ONU is selected from ONU line information tables, the online ONU is set to
ONUi；OLT-B obtains the bandwidth authorization message of ONUi from OLT-A, calculates loop time delays of the ONUi on standby optical link
RTDi-B, and then by RTDi-BCalculate balanced time delays of the ONUi on standby optical link；Step S5.OLT-B calculates ONUi and exists
The difference of the balanced time delay of balanced time delay on standby optical link with ONUi on primary optical link, and by the difference send to
OLT-A；The step S6.OLT-A balanced time delays of each ONU on standby optical link in difference renewal ONU line information tables,
And the balanced time delay by each ONU on standby optical link is sent to corresponding ONU；Step S7.OLT-B detects triggering and switches
Condition, directly enables bandwidth authorizing table；In system all of ONU from POPUP states automatically into working condition, to OLT-B
Bandwidth authorizing respond, send uplink service.
On the basis of above-mentioned technical proposal, in step S2, the WsizeSetting standard be：If Lmax-aAnd Lmax-bIt is
20KM, then Wsize=250 μ s；Otherwise Wsize=450 μ s.
On the basis of above-mentioned technical proposal, the idiographic flow of step S3 is：Step S301.OLT-B obtains ONU to be believed online
Balanced time delay on the primary optical link of breath table and each ONU, and the flags parameters for being used to update EqD are set；Step
S302.OLT-B judges whether ONU line information tables are empty, if so, then wait, until there is ONU to reach the standard grade；Otherwise, step is jumped to
S303；When step S303.OLT-B is judged in ONU line information tables with the presence or absence of balanced on the primary optical link of each ONU
Prolong；If so, jumping to step S305；Otherwise, step S304 is jumped to；Step S304.OLT-B opens second timer T2, the
After two timer T2 time-out, step S301 is jumped to；Step S305.OLT-B is detected by reading manufacturer's mark of optical module
Whether optical module is in place, if so, jumping to step S306；Otherwise, step S304 is jumped to；Step S306.OLT-B reads optical mode
The signal detection pin of block, judges whether to be located at high level, if so, jumping to step S304；Otherwise, step S4 is jumped to.
On the basis of above-mentioned technical proposal, in step S303, the OLT-B by check flags parameters whether set come
Judge with the presence or absence of the balanced time delay on the primary optical link of each ONU in ONU line information tables, if flags parameters set, jump
Go to step S4；Otherwise, step S304 is jumped to.
On the basis of above-mentioned technical proposal, in step S4, the ONUi is of ID minimums in ONU line information tables
ONU。
On the basis of above-mentioned technical proposal, in step S4, balanced time delays of the calculating ONUi on standby optical link
Idiographic flow be：Step S401.OLT-A is by the delivery time T of n-th downlink framesendAnd in n-th downlink frame ONUi band
The deviation post StartTime at the relative frame originating point information moment of authorization message wide is sent to OLT-B；Wherein, the value of N is according to action
Holding time determines；Step S402.OLT-A triggers reference pulse Ref to OLT-B, triggering when n-th downlink frame is sent
OLT-B opens first timer T1；Wherein, the cycle of first timer T1 is detection window size Wsize；Step S403.OLT-
In the duration of first timer T1, OLT-B positions the uplink burst of ONUi by detecting PLOu to B, and record is detected
The moment T of PLOurcv, according to formula ΔRNG-B’=Trcv-Tsend, calculate ranging times of the ONUi on standby optical link
ΔRNG-B’；Step S404.OLT-B obtains loop time delay RTDs of the ONUi on primary optical linki-AWith ONUi in primary optical link
On ranging time ΔRNG-A, according to formula RTDi-B=RTDi-A+(1+nds/nus)(ΔRNG-B’-ΔRNG-A), calculate ONUi and exist
Loop time delay RTD on standby optical linki-B；Wherein, ndsFor down direction light in Optical Distribution Network ODN group velocity folding
Penetrate rate, nusIt is the group velocity refractive index of the light in ODN of up direction；Step S404.OLT-B is according to formula EqD-B=
Teqd-a-RTDi-B, calculate balanced time delay EqD-Bs of the ONUi on standby optical link.
On the basis of above-mentioned technical proposal, step S5, the OLT-B is pressed within the cycle time of second timer T2
The state of irradiation link, repeats balanced time delays of the renewal ONUi on standby optical link balanced on primary optical link with ONUi
The difference of time delay.
On the basis of above-mentioned technical proposal, in step S6, the OLT-A is updated in ONU line information tables with the difference
The idiographic flow of balanced time delays of each ONU on standby optical link is：Equilibriums of the OLT-A according to ONUi on standby optical link
The difference of balanced time delay of the time delay with ONUi on primary optical link, each ONU is in standby light in calculating ONU line information tables
Balanced time delay on link, and all online ONU are sent to by OLT-A.
On the basis of above-mentioned technical proposal, in step S7, the tool that the ONU responds to the bandwidth authorizing of OLT-B
Body flow is：After ONU down-going synchronous, directly reinstate balanced time delays of the ONU on standby optical link to respond the up of OLT-B
Bandwidth authorizing.
The beneficial effects of the present invention are：
1st, the present invention completes standby optical link parameter by standby optical line terminal OLT-B to the monitoring of optical link state
Acquisition, so as to realize that optical link is switched fast.Meanwhile, OLT-B, being capable of real-time update light chain with the change of optical link state
Road parameter information.Therefore, the present invention can quickly be switched to standby optical link, fast quick-recovery when there is optical link switching
The business service of user, can ensure the data safety of user.
2nd, the present invention can obtain corresponding optical link parameter information before switching such that it is able to which realization is quickly switched, no
Need just to detect optical link parameter information after generation optical link is switched.Therefore, customer service service is further shortened
Interrupting time.
3rd, OLT-B obtains the online information of all ONU from OLT-A in the present invention, therefore, when protection system occurs optical link
When switching, OLT-B can carry out bandwidth authorizing to online ONU immediately after as primary OLT, rapid to recover ONU business services,
Improve the service ability to user.
4th, OLT-B judges whether standby optical link can use by monitoring uplink optical signal in the present invention, when standby smooth chain
When road is unavailable, any switching action is not carried out, it is to avoid the stability switched generation, maintain system of system in effective.
5th, when generation optical link is switched, OLT-B need not carry out range finding work to the present invention to each ONU, but directly
Into the service bandwidth mandate to all online ONU；And due to ONU known needed on standby optical link it is balanced when
Prolong, so, when generation optical link is switched in optical link protection system, ONU uses the balanced time delay on standby optical link, together
When, the state of oneself is directly transitted towards working condition (O5) from POPUP states (O6) such that it is able to respond OLT-B's at once
Upstream bandwidth mandate, sends uplink burst, recovers uplink service, realizes being switched fast for optical link.
Brief description of the drawings
Fig. 1 is the status change schematic diagram of traditional ONU；
Fig. 2 is the basic calculation schematic diagram of balanced time delay in the embodiment of the present invention；
Fig. 3 is EPON backbone's optical link protection system structure connection figure in the embodiment of the present invention；
Fig. 4 be the embodiment of the present invention in for the Time Calculation method schematic diagram on double-backbone optical link；
Fig. 5 is EPON backbone's optical link quick method flow switched of protection system realization in the embodiment of the present invention
Figure.
Fig. 6 is the status change schematic diagram of ONU in the embodiment of the present invention.
Specific embodiment
For ease of understanding the present invention, each formula is elaborated below.
EqDi=Teqd-RTDiFormula (1)
It is shown in Figure 2, in EPON, by formula (1) computation and measurement equilibrium time delay, wherein TeqdBe zero away from
It is deviant of the uplink frame relative to corresponding downlink frame that OLT is received from balanced time delay.For the optical link for giving fiber distance
In, TeqdIt is a fixed value, will not be changed in its life cycle.
RTDiIt is loop time delay, it includes descending propagation delay Δ olt, ONU response time RspTimei, upward propagation when
Prolong Δ onuiTotally three parts constitute：
RTDi=Δ olt+RspTimei+ΔonuiFormula (2)
Wherein, ONU response times RspTimei35 μ s are fixed as, deviation is ± 1 μ s.
So, balanced time delays of the measurement ONU on optical link, when must just measure loops of the ONU on optical link
Prolong RTDi。
For OLT-A, exist：
RTDi-A=ΔRNG-A- StartTime formula (3)
Wherein StartTime offsets being the bandwidth authorizing specified by OLT-A.
The ranging time Δ on specific optical link detected for OLT-BRNG-B’For, there is light propagation delay and exist
The standby optical link upward propagation time delay Δ onu of OLT-Bi-BOptical link upward propagation time delay Δ onu primary with OLT-Ai-ADifference
There is following relation：
Δonui-B-Δonui-A=ΔRNG-B’-ΔRNG-AFormula (4)
The derivation of the formula is as follows：
ΔRNG-B’=Δ olt-A+RspTimei+Δonui-B–StartTime；
ΔRNG-A=Δ olt-A+RspTimei+Δonui-A–StartTime；
Subtract each other up and down and can obtain formula (4).
According to the propagation characteristic of light, in same section of optical fiber, descending propagation delay Δ olt and upward propagation time delay Δ onu
Between there is following relation：
Δolt:Δ onu=nds:nusFormula (5)
Wherein, ndsIt is group velocity refractive index of the light of the wavelength that down direction is used in ODN；nusIt is that up direction is adopted
Group velocity refractive index of the light of wavelength in ODN；
For specific passive optical network, marked according to G.983 standard, G.987 standard and 802.3ah, 802.3av
Standard etc., current GPON (Gigabit-Capable Passive Optical Network, gigabit passive optical network) and EPON
The upstream wavelength that (Ethernet Passive Optical Network, Ethernet passive optical network) system is used is 1310 to receive
Rice, downstream wavelength is 1490 nanometers；The upstream wavelength that 10G GPON and 10G EPON system are used is 1270 nanometers, downstream wavelength
It is 1577 nanometers；So, there is following computing formula：
In GPON, EPON system, descending propagation delay Δ olt and upward propagation time delay Δ onu ratios are:
Δolt:Δ onu=n1490:n1310
In 10G GPON, 10G EPON systems, descending propagation delay Δ olt and upward propagation time delay Δ onu ratios are:
Δolt:Δ onu=n1577:n1270
Can be obtained according to formula (2) and formula (5)：
RTDi-B=RTDi-A+(1+nds/nus)(Δonui-B-Δonui-A)
Namely：
RTDi-B=RTDi-A+(1+nds/nus)(ΔRNG-B’-ΔRNG-A) formula (6)
According to formula (1), by RTDi-BThe balanced time delay of the ONUi when OLT-B turns into primary optical link can be calculated.
The present invention is described in further detail below in conjunction with drawings and Examples.
Shown in Figure 3, the embodiment of the present invention provides a kind of EPON backbone optical link protection system, the system bag
Primary optical line terminal OLT-A, standby optical line terminal OLT-B and multiple optical network unit ONUs are included, each ONU passes through 2：N
Optical branching device is connected with OLT-A, OLT-B respectively；The maximum fiber range difference L that OLT-A sets primary optical linkmax-a, herein
Lmax-aThe zero distance equilibrium time delay T of lower useeqd-a, ONU line information tables and upstream physical layer expense PLOu (Physical
Layer Overhead Upstream, physical layer overhead) send to OLT-B；The maximum that OLT-B is set according to standby optical link
Fiber distance difference Lmax-bAnd Lmax-a, detection window size W is setsize；OLT-B obtains ONU line information tables and each ONU
Primary optical link on balanced time delay；When OLT-B detects optical module and has uplink optical signal, selected from ONU line information tables
An online ONU is selected, the online ONU is set to ONUi；OLT-B obtains the bandwidth authorization message of ONUi from OLT-A, calculates ONUi
Loop time delay RTD on standby optical linki-B, and then by RTDi-BWhen calculating balanced on standby optical link of ONUi
Prolong；OLT-B calculates the difference of balanced time delay of balanced time delays of the ONUi on standby optical link with ONUi on primary optical link,
And send to OLT-A the difference；OLT-A each ONU in difference renewal ONU line information tables is on standby optical link
Balanced time delay, and balanced time delay by each ONU on standby optical link sent to corresponding ONU；OLT-B detects triggering and falls
Condition is changed, bandwidth authorizing table is directly enabled；In system all of ONU from POPUP states automatically into working condition, to OLT-
The bandwidth authorizing of B responds, and sends uplink service.
When being switched between primary optical link and standby optical link, for each ONU, its branch road optical link is that do not have
Change, so, the up light of each ONU is to stablize collisionless when reaching optical branching device, so, optical signal passes through key chain
Road reaches OLT-A along primary optical link respectively, and reaches OLT-B along standby optical link, is also steady during arrival OLT-A and OLT-B
It is fixed collisionless, so provide link basis to carry out range finding simultaneously on two optical links.
When OLT-A finds range to ONUi, OLT-B also monitors the uplink burst (burst) of up optical link ONU simultaneously
Optical signal.In the protection of key optical link, the transmitter driving circuit of the optical module of OLT-B does not send light to down direction, but
OLT-B can open the optical signal that drive circuit receives up direction from ODN that receives of optical module, by monitoring up direction
Optical signal is so as to reach the purpose of the specific loop time delay RTD (Round-Trip Delay) calculated in the network structure.
It should be noted that the specific loop time delay that OLT-B is detected in the above-mentioned network structure is not ONU standby at this
With the loop time delay on optical link.It is shown in Figure 4, the optical link road that the specific loop time delay that OLT-B is monitored is actually passed through
Footpath includes：Key optical link (OLT-A main roads are descending) that OLT-A is connected, ONUi branch road optical link (ONUi branch roads are descending,
ONUi branch roads are up), the key optical links that are connected of OLT-B (OLT-B main roads are up).And OLT-B it needs to be determined that loop when
The optical link path prolonged should be：Key optical link (OLT-B main roads are descending), the branch road optical link of ONUi that OLT-B is connected
The key optical link that (ONUi branch roads are descending, ONUi branch roads are up), OLT-B are connected (OLT-B main roads are up).
Shown in Figure 5, the embodiment of the present invention also provides above-mentioned EPON backbone's optical link protection system and realizes soon
The method that speed is switched, the method is comprised the following steps：
The maximum fiber range difference L that step S1.OLT-A sets primary optical linkmax-a, in this Lmax-aThe zero of lower use
The balanced time delay T of distanceeqd-a, ONU line information tables and upstream physical layer expense PLOu sent to OLT-B.
The maximum fiber range difference L that step S2.OLT-B is set according to standby optical linkmax-bAnd Lmax-a, detection is set
Window size Wsize；The WsizeSetting standard be：If Lmax-aAnd Lmax-b20KM is, then Wsize=250 μ s；Otherwise Wsize
=450 μ s.
Step S3.OLT-B obtains the balanced time delay on the primary optical link of ONU line information tables and each ONU；It is preferred that
, the idiographic flow of step S3 is：
Step S301.OLT-B obtains the balanced time delay on the primary optical link of ONU line information tables and each ONU, and
One flags parameters for being used to update EqD is set.
Step S302.OLT-B judges whether ONU line information tables are empty, if so, then wait, until there is ONU to reach the standard grade；It is no
Then, step S303 is jumped to.
Step S303.OLT-B is judged in ONU line information tables with the presence or absence of the equilibrium on the primary optical link of each ONU
Time delay；If so, jumping to step S305；Otherwise, step S304 is jumped to；Preferably, the OLT-B is by checking flags parameters
Whether set judges the balanced time delay on the primary optical link in ONU line information tables with the presence or absence of each ONU, if mark ginseng
Number set, jumps to step S4；Otherwise, step S304 is jumped to.
Step S304.OLT-B opens second timer T2, after second timer T2 time-out, jumps to step S301；Its
In, the cycle of the second timer T2 is set to 60 seconds.
Step S305.OLT-B detects whether optical module is in place by reading manufacturer's mark of optical module, if so, redirecting
To step S306；Otherwise, step S304 is jumped to.
Step S306.OLT-B reads the signal detection pin of optical module, judges whether to be located at high level, if so, jumping to
Step S304；Otherwise, step S4 is jumped to.
When step S4.OLT-B detects optical module and has uplink optical signal, selected from ONU line information tables one it is online
ONU, ONUi is set to by the online ONU, it is preferred that the ONUi is an ONU of ID minimums in ONU line information tables；OLT-B
The bandwidth authorization message of ONUi is obtained from OLT-A, loop time delay RTDs of the ONUi on standby optical link is calculatedi-B, and then pass through
RTDi-BCalculate balanced time delays of the ONUi on standby optical link；Preferably, the calculating ONUi is equal on standby optical link
Weigh time delay idiographic flow be：
Step S401.OLT-A is by the delivery time T of n-th downlink framesendAnd the bandwidth of ONUi is awarded in n-th downlink frame
The deviation post StartTime at the relative frame originating point information moment of power information is sent to OLT-B；Wherein, the value of N takes according to action
Time determines.
Step S402.OLT-A triggers reference pulse Ref to OLT-B when n-th downlink frame is sent, and triggering OLT-B is opened
First timer T1；Wherein, the cycle of first timer T1 is detection window size Wsize。
In the duration of first timer T1, OLT-B positions the upper of ONUi by detecting PLOu to step S403.OLT-B
Row burst, and record the moment T for detecting PLOurcv, according to formula ΔRNG-B’=Trcv-Tsend, ONUi is calculated in standby light
Ranging time Δ on linkRNG-B’。
Step S404.OLT-B obtains loop time delay RTDs of the ONUi on primary optical linki-AWith ONUi in primary optical link
On ranging time ΔRNG-A, according to formula
RTDi-B=RTDi-A+(1+nds/nus)(ΔRNG-B’-ΔRNG-A),
Calculate loop time delay RTDs of the ONUi on standby optical linki-B；Wherein, ndsFor the light of down direction is distributed in light
Group velocity refractive index in network ODN, nusIt is the group velocity refractive index of the light in ODN of up direction；In G bit passive light
In network G PON and Ethernet passive optical network EPON system, the wavelength of the light of up direction is 1310 nanometers, down direction
The wavelength of light is 1490 nanometers；In 10G GPON and 10G EPON systems, the wavelength of the light of up direction is 1270 nanometers, under
The wavelength of the light of line direction is 1577 nanometers.
Step S404.OLT-B is according to formula
EqD-B=Teqd-a-RTDi-B,
Calculate balanced time delay EqD-Bs of the ONUi on standby optical link.
It is equal on primary optical link with ONUi that step S5.OLT-B calculates balanced time delays of the ONUi on standby optical link
The difference of the time delay that weighs, and the difference is sent to OLT-A；Preferably, cycle times of the OLT-B in second timer T2
It is interior, according to the state of optical link, repeat to update balanced time delays of the ONUi on standby optical link with ONUi on primary optical link
Balanced time delay difference.
When the step S6.OLT-A differences update balanced on standby optical link of each ONU in ONU line information tables
Prolong, and balanced time delay by each ONU on standby optical link is sent to corresponding ONU.Specifically, OLT-A is according to the difference
It is added in the balanced time delay of key light link with each ONU in ONU line information tables, obtains each ONU on standby optical link
Balanced time delay；OLT-A sends this information to each ONU by downlink frame.Wherein, the OLT-A differences update ONU and exist
The idiographic flow of balanced time delays of each ONU on standby optical link is in line information table：OLT-A is according to ONUi in standby smooth chain
The difference of the balanced time delay of balanced time delay on road with ONUi on primary optical link, calculates each in ONU line information tables
Balanced time delays of the ONU on standby optical link, and all online ONU are sent to by OLT-A.
Step S7.OLT-B detects triggering protection criteria, directly enables bandwidth authorizing table；In system all of ONU from
Automatically into working condition, the bandwidth authorizing to OLT-B responds POPUP states, sends uplink service.Wherein, it is described
ONU is to the idiographic flow that the bandwidth authorizing of OLT-B responds：After ONU down-going synchronous, the ONU is directly reinstated in standby light
Balanced time delay on link responds the upstream bandwidth mandate of OLT-B.
Shown in Figure 6, when generation optical link is switched in optical link protection system, OLT-B is changed into primary working method,
Range finding work need not be carried out to each ONU, but is directly entered the service bandwidth mandate to all online ONU；And due to ONU
Know the balanced time delay needed on standby optical link, so, when generation optical link is switched in optical link protection system,
ONU uses the balanced time delay on standby optical link, meanwhile, the state of oneself is directly transitted towards work from POPUP states (O6)
Make state (O5), such that it is able to respond the upstream bandwidth mandate of OLT-B at once, send uplink burst, recover uplink service.
The present invention is not limited to the above-described embodiments, for those skilled in the art, is not departing from
On the premise of the principle of the invention, some improvements and modifications can also be made, these improvements and modifications are also considered as protection of the invention
Within the scope of.The content not being described in detail in this specification belongs to prior art known to professional and technical personnel in the field.
Claims (10)
1. a kind of EPON backbone optical link protection system, the system includes primary optical line terminal OLT-A, standby light
Road terminal OLT-B and multiple optical network unit ONUs, each ONU pass through 2：N optical branching devices are connected with OLT-A, OLT-B respectively；
It is characterized in that：
The maximum fiber range difference L that OLT-A sets primary optical linkmax-a, in this Lmax-aThe zero distance equilibrium time delay of lower use
Teqd-a, ONU line information tables and upstream physical layer expense PLOu sent to OLT-B；
The maximum fiber range difference L that OLT-B is set according to standby optical linkmax-bAnd Lmax-a, detection window size W is setsize；
OLT-B obtains the balanced time delay on the primary optical link of ONU line information tables and each ONU；
When OLT-B detects optical module and has uplink optical signal, an online ONU is selected from ONU line information tables, this is online
ONU is set to ONUi；OLT-B obtains the bandwidth authorization message of ONUi from OLT-A, when calculating loops of the ONUi on standby optical link
Prolong RTDi-B, and then by RTDi-BCalculate balanced time delays of the ONUi on standby optical link；
OLT-B calculates the difference of balanced time delay of balanced time delays of the ONUi on standby optical link with ONUi on primary optical link
Value, and the difference is sent to OLT-A；
OLT-A with the difference update ONU line information tables in balanced time delays of each ONU on standby optical link, and by each
Balanced time delays of the ONU on standby optical link is sent to corresponding ONU；
OLT-B detects triggering protection criteria, directly enables bandwidth authorizing table；All of ONU is automatic from POPUP states in system
Working condition is entered into, the bandwidth authorizing to OLT-B responds, send uplink service.
2. the EPON backbone's optical link protection system described in claim 1 realizes the quick method switched, and its feature exists
In the method is comprised the following steps：
The maximum fiber range difference L that step S1.OLT-A sets primary optical linkmax-a, in this Lmax-aThe zero distance of lower use is equal
Weighing apparatus time delay Teqd-a, ONU line information tables and upstream physical layer expense PLOu sent to OLT-B；
The maximum fiber range difference L that step S2.OLT-B is set according to standby optical linkmax-bAnd Lmax-a, it is big that detection window is set
Small Wsize；
Step S3.OLT-B obtains the balanced time delay on the primary optical link of ONU line information tables and each ONU；
When step S4.OLT-B detects optical module and has uplink optical signal, an online ONU is selected from ONU line information tables,
The online ONU is set to ONUi；OLT-B obtains the bandwidth authorization message of ONUi from OLT-A, and ONUi is on standby optical link for calculating
Loop time delay RTDi-B, and then by RTDi-BCalculate balanced time delays of the ONUi on standby optical link；
Step S5.OLT-B calculates balanced time delays of the ONUi on standby optical link with ONUi during balanced on primary optical link
The difference prolonged, and the difference is sent to OLT-A；
The step S6.OLT-A balanced time delays of each ONU on standby optical link in difference renewal ONU line information tables, and
Balanced time delay by each ONU on standby optical link is sent to corresponding ONU；
Step S7.OLT-B detects triggering protection criteria, directly enables bandwidth authorizing table；All of ONU is from POPUP in system
Automatically into working condition, the bandwidth authorizing to OLT-B responds state, sends uplink service.
3. EPON backbone's optical link protection system as claimed in claim 2 realizes the quick method switched, its feature
It is：In step S2, the WsizeSetting standard be：If Lmax-aAnd Lmax-b20KM is, then Wsize=250 μ s；Otherwise
Wsize=450 μ s.
4. EPON backbone's optical link protection system as claimed in claim 2 realizes the quick method switched, its feature
It is that the idiographic flow of step S3 is：
Step S301.OLT-B obtains the balanced time delay on the primary optical link of ONU line information tables and each ONU, and sets
One flags parameters for being used to update balanced time delay EqD；
Step S302.OLT-B judges whether ONU line information tables are empty, if so, then wait, until there is ONU to reach the standard grade；Otherwise, jump
Go to step S303；
Step S303.OLT-B is judged in ONU line information tables with the presence or absence of the balanced time delay on the primary optical link of each ONU；
If so, jumping to step S305；Otherwise, step S304 is jumped to；
Step S304.OLT-B opens second timer T2, after second timer T2 time-out, jumps to step S301；
Step S305.OLT-B detects whether optical module is in place by reading manufacturer's mark of optical module, if so, jumping to step
Rapid S306；Otherwise, step S304 is jumped to；
Step S306.OLT-B reads the signal detection pin of optical module, judges whether to be located at high level, if so, jumping to step
S304；Otherwise, step S4 is jumped to.
5. EPON backbone's optical link protection system as claimed in claim 4 realizes the quick method switched, its feature
It is：In step S303, the OLT-B is by checking whether whether set judges to be deposited in ONU line information tables to flags parameters
Balanced time delay on the primary optical link of each ONU, if flags parameters set, jumps to step S4；Otherwise, step is jumped to
S304。
6. EPON backbone's optical link protection system as claimed in claim 2 realizes the quick method switched, its feature
It is that in step S4, the ONUi is an ONU of ID minimums in ONU line information tables.
7. EPON backbone's optical link protection system as claimed in claim 2 realizes the quick method switched, its feature
It is that in step S4, the idiographic flow of balanced time delays of the calculating ONUi on standby optical link is：
Step S401.OLT-A is by the delivery time T of n-th downlink framesendAnd in n-th downlink frame ONUi bandwidth authorization message
The deviation post StartTime at relative frame originating point information moment send to OLT-B；Wherein, the value of N according to action holding time come
It is determined that；
Step S402.OLT-A triggers reference pulse Ref to OLT-B when n-th downlink frame is sent, and triggering OLT-B opens first
Timer T1；Wherein, the cycle of first timer T1 is detection window size Wsize；
In the duration of first timer T1, OLT-B positions the up prominent of ONUi by detecting PLOu to step S403.OLT-B
Hair, and record the moment T for detecting PLOurcv, according to formula ΔRNG-B’=Trcv-Tsend, ONUi is calculated in standby optical link
On ranging time ΔRNG-B’；
Step S404.OLT-B obtains loop time delay RTDs of the ONUi on primary optical linki-AWith ONUi on primary optical link
Ranging time ΔRNG-A, according to formula
RTDi-B=RTDi-A+(1+nds/nus)(ΔRNG-B’-ΔRNG-A),
Calculate loop time delay RTDs of the ONUi on standby optical linki-B；Wherein, ndsIt is the light of down direction in Optical Distribution Network
Group velocity refractive index in ODN, nusIt is the group velocity refractive index of the light in ODN of up direction；
Step S405.OLT-B is according to formula
EqD-B=Teqd-a-RTDi-B,
Calculate balanced time delay EqD-Bs of the ONUi on standby optical link.
8. EPON backbone's optical link protection system as claimed in claim 2 realizes the quick method switched, its feature
It is：Step S5, the OLT-B, according to the state of optical link, repeat to update ONUi within the cycle time of second timer T2
The difference of the balanced time delay of balanced time delay on standby optical link with ONUi on primary optical link.
9. EPON backbone's optical link protection system as claimed in claim 2 realizes the quick method switched, its feature
It is, in step S6, the OLT-A equilibriums of each ONU on standby optical link in difference renewal ONU line information tables
The idiographic flow of time delay is：Balanced time delays of the OLT-A according to ONUi on standby optical link is with ONUi on primary optical link
The difference of balanced time delay, calculates balanced time delays of each ONU on standby optical link in ONU line information tables, and by OLT-A
It is sent to all online ONU.
10. the EPON backbone's optical link protection system as any one of claim 2 to 9 realizes what is quickly switched
Method, it is characterised in that in step S7, the ONU is to the idiographic flow that the bandwidth authorizing of OLT-B responds：ONU is descending
After synchronization, directly reinstate balanced time delays of the ONU on standby optical link to respond the upstream bandwidth mandate of OLT-B.
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| CN102084665A (en) * | 2008-03-17 | 2011-06-01 | 爱立信电话股份有限公司 | Immediate protection scheme for passive optical network |
| CN101826928A (en) * | 2009-03-03 | 2010-09-08 | 中兴通讯股份有限公司 | Method and device for realizing PON (Passive Optical Network) system service recovery |
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