Optical line terminal and main / standby switching method thereof
By establishing a remote procedure call communication channel and data packet label processing in the optical fiber backup group, the problem of data packet loss during the main and backup OLT switching process is solved, and the continuity and reliability of data transmission in the optical network are achieved.
Patent Information
- Application Number
- CN202510895256.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-09-09
AI Technical Summary
In a PON network, the downstream optical signal is interrupted during the switchover between the primary and backup OLTs, resulting in data packet loss.
By establishing a remote procedure call communication channel in the optical fiber backup group, receiving the active-standby switching notification message and adding double VLAN tags to the data message, stripping off the retained VLAN tags and buffering the data message, and switching the PON port state from protection to working state when the active-standby switching occurs, and sending the buffered data message.
This avoids the loss of downlink data packets during the switchover between the primary and standby OLTs, ensuring the continuity and reliability of data transmission.
Smart Images
Figure CN120614040A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to optical network technology, in particular to an optical line terminal and a method for switching between an optical line terminal and a standby line terminal. Background Art
[0002] PON (Passive Optical Network) is a point-to-multipoint passive optical network. In a PON network, to address the risk of single-point failure between the OLT and ONU, the standard defines four PON redundancy methods.
[0003] The Type B dual-homing architecture provides a redundant OLT (Optical Line Terminal) protection mechanism. Each optical network unit (ONU) is connected to a single optical fiber, which is connected to two OLTs via a 2:N splitter.
[0004] In a fiber backup group, the primary and backup OLTs synchronize data via a TCP connection. The primary OLT's active OLT port forwards optical signals. If the trunk fiber connecting the primary OLT to the optical splitter shorts or the PON port is disconnected (down), the primary and backup OLTs in the backup group automatically switch over. The backup OLT becomes the new primary OLT and forwards optical signals based on the synchronized data. However, during the switchover, the downstream optical signal is interrupted, resulting in downstream data packet loss until the switchover is complete. Summary of the Invention
[0005] The purpose of the present application is to provide an optical line terminal and a method for active / standby switching thereof, so as to reduce downlink data packet loss in an optical network.
[0006] To achieve the above-mentioned objectives, the present application provides a method for active-standby switching of an optical line terminal, wherein the method includes establishing a remote procedure call communication channel through a direct link of a peer optical line terminal of a directly connected optical fiber backup group; receiving a first active-standby switching notification message through the remote procedure call communication channel; receiving a first data message with a double VLAN tag and an outer VLAN tag being a reserved VLAN tag through the direct link; stripping the reserved VLAN tag from the first data message and caching it; switching a local passive optical network (PON) port connected to an optical splitter from a protection state to an operating state based on the active-standby switching notification message or the first data message; and sending the cached first data message through the local PON port in the operating state.
[0007] To achieve the above-mentioned objectives, the present application also provides a device for active-standby switching of an optical line terminal; wherein the device includes a processor and a memory; the memory stores instructions executed by the processor; wherein the processor executes the following processing by running machine-executable instructions: establishing a remote procedure call communication channel through a direct link of the opposite optical line terminal of the direct-connected optical fiber backup group; receiving a first active-standby switching notification message through the remote procedure call communication channel; receiving a first data packet with a double-layer VLAN tag and an outer VLAN tag being a reserved VLAN tag through the direct link; stripping off the reserved VLAN tag of the first data packet and caching it; based on the active-standby switching notification message or the first data packet, switching a local passive optical network (PON) port connected to the splitter from a protection state to a working state and sending the cached first data packet through the local PON port in the working state.
[0008] The beneficial effect of the present application is that when the main link in the optical fiber backup group fails, the main OLT triggers the backup OLT to switch the backup link to the new main link through RPC messages and data messages, thereby avoiding packet loss caused by the discarding of downlink data messages when the main and backup OLTs switch the main and backup links. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 A flowchart of an embodiment of a method for active / standby switching of an optical line terminal provided by the present application;
[0010] Figure 2 A schematic diagram of a dual-homing architecture for an optical line terminal;
[0011] Figure 3 for Figure 2 A schematic diagram of an embodiment of active / standby switching of an optical line terminal provided by this application under the architecture;
[0012] Figure 4 for Figure 2 A schematic diagram of another embodiment of active / standby switching of an optical line terminal provided by the present application under the architecture;
[0013] Figure 5 Shown is a schematic diagram of an optical line terminal embodiment provided by the present application. DETAILED DESCRIPTION
[0014] The present invention will be described in detail with reference to a plurality of examples shown in the accompanying drawings. In the following detailed description, a number of specific details are provided to provide a comprehensive understanding of the present invention. Known methods, steps, components, and circuits are not described in detail in the examples to avoid obscuring the understanding of the examples.
[0015] Among the terms used, the term "including" means including but not limited to; the term "containing" means including but not limited to; the terms "above," "within," and "below" are inclusive; the terms "greater than" and "less than" are exclusive. The term "based on" means based on at least a portion.
[0016] Figure 1 The flowchart of the method embodiment of the active / standby switching of an optical line terminal provided by the present application is shown; the embodiment includes:
[0017] Step 101, establishing a remote procedure call communication channel through a direct link of a peer optical line terminal of a direct optical fiber backup group;
[0018] Step 102: Receive a first active / standby switch notification message via a remote procedure call communication channel;
[0019] Step 103: receiving a first data message with a reserved VLAN tag via a direct link;
[0020] Step 104: caching the first data message with the reserved VLAN tag;
[0021] Step 105: Based on the active / standby switching notification message or the first data packet with the reserved VLAN tag, the local passive optical network (PON) port connected to the optical splitter is switched from a protection state to a working state.
[0022] Step 106: remove the reserved VLAN tag of the buffered first data message and send it through the local PON port in working state.
[0023] Figure 1 The beneficial effect of the embodiment is that when the main link in the optical fiber backup group fails, the main OLT triggers the backup OLT to switch the backup link to the new main link through both remote procedure call messages and data messages, thereby avoiding packet loss caused by the discarding of downlink data messages when the main and backup OLTs switch the main and backup links.
[0024] Figure 2 Schematic diagram of the dual-homing architecture of an optical line terminal. Figure 2 In the example, optical line terminals OLT1 and OLT2 form a fiber backup group. In this group, OLT1 serves as the primary optical line terminal, and OLT2 serves as the backup optical line terminal. OLT1 and OLT2, along with switch S1, are located in a STP (Spanning Tree Protocol) loop-free network 200. Switch S1, within STP loop-free network 200, sends downstream unicast / broadcast data packets to OLT1 and OLT2, respectively.
[0025] In the fiber backup group, the PON port P1 of the main optical line terminal OLT1 is in working state, sending downstream unicast / broadcast data packets to the optical splitter 24 through the link L1; the PON port P2 of the backup optical line terminal OLT2 is in protection state and does not forward downstream unicast / broadcast data packets; thus, in the fiber backup group, only the main link L1 is forwarding, and the backup link L2 is not forwarding.
[0026] The optical line terminals OLT1 and OLT2 send the downstream unicast / broadcast data packets received by the STP loop-free network to the connected hosts PC26 and PC27.
[0027] The main optical line terminals OLT1 and OLT2 establish a remote procedure call communication channel through the direct link L3.
[0028] Figure 3 for Figure 2 Schematic diagram of an embodiment of active-standby switching of an optical line terminal provided by this application under the architecture.
[0029] Figure 3 In the process, the optical line terminal OLT1 detects that the local PON port P1 loses the optical signal; and sends a master-slave switch notification message through the remote procedure call communication channel.
[0030] The optical line terminal OLT1 adds a reserved VLAN 4095 tag to the downlink unicast data packet 3a of the PON port P1, and sends it to the backup optical line terminal OLT2 through the direct link.
[0031] The optical line terminal OLT2 buffers the downlink unicast data packet 3a with the reserved VLAN 4095 tag.
[0032] In this application, by adding a VLAN tag of a reserved VLAN to a downlink data message, it is used for a special redirected data message sent via a direct link. The reserved VLAN 4095 of this application is only used as an example, but is not limited to using only this VLAN.
[0033] In this application, optical line terminal OLT1 has already notified the peer optical line terminal OLT2 of the active / standby link switchover notification message via a remote procedure call message. However, the time at which the remote procedure call message and the downlink unicast data packet with the reserved VLAN 4095 tag arrive at the peer optical line terminal OLT2 is uncertain. Therefore, optical line terminal OLT2 can initiate active / standby link switchover based on whichever of the active / standby link switchover notification message or the data packet with the reserved VLAN 4095 tag arrives first.
[0034] The optical line terminal OLT2 switches the PON port P2 in the protection state to the working state and opens the optical channel. In this way, the optical line terminal OLT2 establishes a connection with the host PC25 through the PON port P2.
[0035] After completing the active / standby link switchover, OLT2 sends a downstream unicast data packet 3a through PON port P2, stripping off the retained VLAN 4095 tag. The redirection ACL entry in OLT2 takes effect, redirecting the downstream unicast data packet 3a, which retains the VLAN 4095 tag, to the local port of direct link L3. Thus, OLT2 redirects the downstream unicast data packet 3a, which retains the VLAN 4095 tag, to OLT1 via direct link 3a.
[0036] After receiving downlink unicast data packet 3a with the retained VLAN tag 4095, OLT1 determines that OLT2 has completed the primary link switchover operation, identifies the packet as a unicast packet, removes the retained VLAN tag 4095, and transmits it through the local port connected to direct link L3. The recovered downlink unicast data packet 3a is then sent to OLT2.
[0037] The optical line terminal OLT2 receives the original downlink unicast data packet 3a via the direct link L3, determines that the active / standby switching is completed, and discards the original downlink unicast data packet 3a arriving via the direct link L3.
[0038] Figure 4 for Figure 2 Schematic diagram of another embodiment of active-standby switching of an optical line terminal provided by this application under the architecture.
[0039] Figure 4 In the process, the main optical line terminal OLT1 detects that the local PON port P1 loses the optical signal; and sends a master-slave switching notification message through the remote procedure call communication channel.
[0040] The main optical line terminal OLT1 uses the PON port P1 as the egress port to add a reserved VLAN 4095 tag to the downlink broadcast data message 4a, and sends it to the backup optical line terminal OLT2 through a direct link.
[0041] OLT1 also sends an original downstream broadcast data message 4a through the STP loop-free network 200.
[0042] The optical line terminal OLT2 buffers the downstream broadcast data message 4a received through the direct link L3 and carries the reserved VLAN 4095 tag. The optical line terminal OLT2 sends the downstream broadcast data message received by the STP loop-free network 200 through an Ethernet port other than the PON port P2.
[0043] In this application, a VLAN tag of a reserved VLAN is added to a downlink data message for a special redirected data message sent through a direct link. The reserved VLAN 4095 in this application is only used as an example, but is not limited to the use of only this VLAN.
[0044] In this application, optical line terminal OLT1 has already notified the peer optical line terminal OLT2 of the master / slave switch notification message via a remote procedure call message. However, the time at which the master / slave switch notification message and the downlink unicast data packet with the reserved VLAN 4095 tag arrive at the peer optical line terminal OLT2 is uncertain. Optical line terminal OLT2 can initiate a master / slave link switch based on whichever arrives first: the master / slave switch notification message or the data packet with the reserved VLAN 4095 tag.
[0045] The optical line terminal OLT2 switches the PON port P2 from the protection state to the working state, opens the optical channel, and establishes a connection with the host PC25 through the PON port P2.
[0046] After completing the active / standby link switchover, OLT2 sends a downstream broadcast data packet 4a with the retained VLAN 4095 tag removed through PON port P2. The redirection ACL entry takes effect, redirecting the downstream broadcast data packet 4a with the retained VLAN 4095 tag to the local port of direct link L3. OLT2 then redirects the downstream broadcast data packet 4a with the retained VLAN 4095 tag to OLT1 through direct link 3a.
[0047] After receiving the downlink broadcast data message 4a with the reserved VLAN 4095 tag, the optical line terminal OLT1 determines that the optical line terminal OLT2 has completed the main link switching operation, identifies the message type as a broadcast message, and discards it.
[0048] Figure 5 A schematic diagram of an optical line terminal embodiment provided by the present application is shown. The device includes a processor and a memory; the memory stores machine-executable instructions; wherein the processor, by executing the machine-executable instructions, is configured to perform the following processing: establishing a remote procedure call communication channel via a dedicated link to a peer optical line terminal directly connected to a fiber backup group; receiving a first active / standby switchover notification message via the remote procedure call communication channel; receiving a first data packet with a retained VLAN tag via the dedicated link; buffering the first data packet with the retained VLAN tag; switching a local passive optical network (PON) port connected to an optical splitter from a protection state to an operating state based on the active / standby switchover notification message or the first data packet with the retained VLAN tag; and removing the retained VLAN tag from the buffered first data packet and transmitting the packet through the operating local PON port.
[0049] The processor is further configured to execute the following processing by running machine-executable instructions: determining that the first data packet is a unicast data packet; receiving the first data packet with the reserved VLAN tag stripped off through a dedicated link; determining that the active-standby switching is completed; and discarding the received first data packet with the reserved VLAN tag stripped off.
[0050] The processor is further configured to perform the following processing by running machine-executable instructions: determining that the first data packet is a broadcast data packet, receiving another first data packet that does not carry a reserved VLAN tag through a Spanning Tree Protocol (STP) loop-free network; identifying that the type of the first data packet is a broadcast data packet, and sending the first data packet that does not carry a reserved VLAN tag through other ports other than a local PON port.
[0051] The processor is further configured to execute the following processing by running machine executable instructions: detecting a loss of an optical signal at a local PON port; sending a second active / standby switching notification message via a remote procedure call communication channel; and receiving a second data packet with a double-layer VLAN tag and an outer VLAN tag being a reserved VLAN tag via a dedicated link.
[0052] The processor is further configured to execute the following processing by running machine-executable instructions: receiving a second data packet with a reserved VLAN tag through a directly connected link; identifying the type of the second data packet as a unicast data packet, and stripping the reserved VLAN tag of the second data packet; redirecting the second data packet to the opposite optical line terminal through a dedicated link; or identifying the type of the second data packet as a broadcast data packet, and discarding the second data packet.
[0053] In the present disclosure, a machine-readable storage medium may be any electronic, magnetic, optical, or other physical storage device for storing or containing information (e.g., executable instructions, data, etc.). For example, any machine-readable storage medium described herein may be any type of random access memory (RAM), volatile memory, non-volatile memory, flash memory, storage drive (e.g., hard drive), solid-state drive, any type of storage optical disk (e.g., optical disk, DVD, etc.), and similar devices, or a combination thereof. In addition, any machine-readable storage medium described herein may be a non-transitory machine-readable storage medium.
[0054] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.
Claims
1. A method for active / standby switching of an optical line terminal, characterized in that: The method comprises the following steps: Establishing a remote procedure call communication channel through a direct link of the opposite optical line terminal of the direct optical fiber backup group; receiving a first active / standby switching notification message through the remote procedure call communication channel; receiving a first data packet with a reserved VLAN tag through the direct link; caching the first data message with the reserved VLAN tag; Based on the active / standby switching notification message or the first data packet with the reserved VLAN tag, switching the local passive optical network (PON) port connected to the optical splitter from a protection state to a working state; The reserved VLAN tag of the buffered first data message is stripped off and the data message is sent through the local PON port in working state.
2. The method according to claim 1, characterized in that The first data message is a unicast data message; the method further includes: The first data message with the reserved VLAN tag removed is received through the direct link, and it is determined that the primary / backup link switching is completed, and the received first data message with the reserved VLAN tag removed is discarded.
3. The method according to claim 1, characterized in that The first data message is a broadcast data message, and the method further includes: Another first data packet not carrying a reserved VLAN tag is received through a Spanning Tree Protocol (STP) loop-free network; Identify the type of the first data packet as the broadcast data packet, and send the first data packet without the reserved VLAN tag through a port other than the local PON port.
4. The method according to claim 1, wherein The method further comprises, Detecting a loss of optical signal at the local PON port; Sending a second active-standby switching notification message through the remote procedure call communication channel; adding the reserved VLAN tag to a second data packet whose egress port is the local PON port; The second data packet with the reserved VLAN tag is received through the direct link.
5. The method according to claim 4, characterized in that The method further comprises, receiving the second data packet with the reserved VLAN tag through the direct link; Identifying that the type of the second data packet is a unicast data packet, stripping the reserved VLAN tag of the second data packet; redirecting the second data packet to the opposite optical line terminal through the direct link; or, Identify that the type of the second data packet is a broadcast data packet, and discard the second data packet.
6. A device for active / standby switching of an optical line terminal, characterized in that: The device includes a processor and a memory; the memory stores instructions executed by the processor; wherein the processor executes the instructions to perform the following processing: Establishing a remote procedure call communication channel through a direct link of the opposite optical line terminal of the direct optical fiber backup group; receiving a first active / standby switching notification message through the remote procedure call communication channel; receiving a first data packet with a reserved VLAN tag through the direct link; caching the first data message with the reserved VLAN tag; Based on the active / standby switching notification message or the first data packet with the reserved VLAN tag, switching the local passive optical network (PON) port connected to the optical splitter from a protection state to a working state; The reserved VLAN tag of the buffered first data message is stripped off, and the data message is sent through the local PON port in a working state.
7. The device according to claim 6, characterized in that The first data packet is a unicast data packet; the processor is also used to perform the following processing by running the instruction: receiving the first data packet with the retained VLAN tag stripped off through the direct link, determining that the master-slave switching is completed, and discarding the received first data packet with the retained VLAN tag stripped off.
8. The device according to claim 6, characterized in that The first data message is a broadcast data message, and the processor is further configured to perform the following processing by running the instruction: Another first data packet not carrying a reserved VLAN tag is received through a Spanning Tree Protocol (STP) loop-free network; Identify the type of the first data packet as the broadcast data packet, and send the first data packet without the reserved VLAN tag through a port other than the local PON port.
9. The device according to claim 6, characterized in that The processor is further configured to execute the following processing by executing the instructions: Detecting a loss of optical signal at the local PON port; Sending a second active-standby switching notification message through the remote procedure call communication channel; A second data message with a double-layer VLAN tag and an outer VLAN tag being a reserved VLAN tag is received through the direct link.
10. The device according to claim 9, characterized in that The processor is further configured to execute the following processing by executing the instructions: receiving the second data packet with the reserved VLAN tag through the direct link; Identifying that the type of the second data packet is a unicast data packet, stripping the reserved VLAN tag of the second data packet; redirecting the second data packet to the opposite optical line terminal through the direct link; or, Identify that the type of the second data packet is a broadcast data packet, and discard the second data packet.