CN106533811B - SDH-based redundant communication system and redundancy protection method thereof - Google Patents
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Abstract
The invention is a redundant communication system based on SDH and its redundant protection method, the SDH system of the front and back ends of the system has 2 pieces of SDH of main and backup respectively, the main and backup SDH of the local end, 2 pieces of main and backup SDH optical fiber connection of the heteroend, form SDH redundant communication network. The front end SDH is also provided with a MAC address learning module. The computers of the front-end and back-end control systems and the video voice transmission equipment are respectively connected with the local SDH through Ethernet or E1. The redundancy protection method selects the transmission path with the highest priority in the SDH redundancy communication network, and the priority of the SDH main equipment and the main link is high. SDH detects the state of each interface, and sends to each SDH, when fault occurs, selecting the highest priority path in the available paths, four SDH switch at the same time, and the recovery of data transmission is within 800 ms. The invention can quickly detect interface state and quickly learn IP address by MAC, to realize quick redundancy protection and recovery of service transmission.
Description
Technical Field
The invention relates to SDH (Synchronous Digital Hierarchy synchronous digital hierarchy) communication transmission technology, in particular to a redundant communication system based on SDH and a redundant protection method thereof.
Background
With the development of science and technology, the modern society has increasingly depended on communication. Design considerations have become crucial as to how to implement a network that automatically recovers carried traffic from a failed fault in a very short time without human intervention, i.e., the survivability of the communication network. The service restoration time and the range of service restoration are typically taken as two important scales for measuring the viability of the communication network.
There are two types of SDH protection methods commonly used at present:
1) The line protection switching mode is that when the transmission of the working channel of the communication network is interrupted or the performance is deteriorated to a certain extent, the system switching equipment automatically switches the main signal to the standby optical fiber system for transmission, so that the receiving end can still receive the normal signal and can not feel that the network has failed. The service recovery time of the protection mode is fast and can be shorter than 50ms, and the protection mode is very effective to failure faults of optical or electric components of the network node. However, when the optical cable fails, all optical fibers (including the primary and the standby) in the same cable core are cut, so that the protection mode is not effective.
2) Ring net protection
Connecting the communication network nodes in a ring may further improve the survivability and cost of the communication network. The self-healing ring structure is divided into channel switching and multiplexing section switching. For channel switching, the protection of traffic is based on channels, and an AIS (Alarm Indication Signal alarm indication signal) signal of a channel is generally used to determine whether to switch; for multiplex section switching, the protection of the traffic is based on the multiplex section, and the switching is determined according to the quality of the signal of the multiplex section of each pair of nodes, and two protection modes of 1+1 and 1:N are commonly used.
The ethernet service is one of the most important services in the communication system, and in order to ensure reliable data transmission, a multi-device redundancy automatic routing mode is mainly adopted for realizing. In the running process of the system, when the existing path is detected to be unreachable, a new route is recalculated and established through a dynamic routing protocol. The time for establishing the new route is 600 ms-2000 ms, the time for establishing the new route is uncontrollable, and the data transmission path is automatically selected and uncontrollable. In communication systems where reliability requirements are high, these uncertainties are not allowed.
Disclosure of Invention
The invention aims to design a redundant communication system based on SDH, wherein the front-end system and the back-end system respectively comprise a control system and an SDH system, the front-end SDH system and the back-end SDH system are respectively a main SDH device and a standby SDH device, the main SDH and the standby SDH of the front-end are respectively, and the 2 main SDH and the 2 standby SDH of the different-end are connected through optical fibers to form an SDH redundant communication network. The front-end control system comprises one or more of a control computer, a video transmission device and a voice transmission device, and is respectively connected with the local SDH device through an Ethernet or an E1 coaxial cable. The back-end control system comprises one or more of a management computer, a video monitoring device and a voice switching device, wherein the management computer is connected with the back-end switching system through an Ethernet, the back-end switching system is connected with the back-end SDH system through the Ethernet, and the video monitoring device and the voice switching device are respectively connected with the local-end SDH device through an Ethernet or an E1 coaxial cable.
Another object of the present invention is to design the redundancy protection method of the above-mentioned SDH-based redundancy communication system, and select a transmission path with a high priority in the SDH redundancy communication network as the current transmission path, where the SDH main device and the main link have a higher priority than the standby device and the standby link. And when faults occur, selecting the path with the highest priority in the available transmission paths, switching four SDH simultaneously, and recovering the data transmission within 800 ms.
The invention relates to a redundant communication system based on SDH, which comprises a front-end system and a back-end system, wherein the front-end system comprises a front-end control system and a front-end SDH system, the front-end control system comprises one or more of a control computer, video transmission equipment and voice transmission equipment, the control computer and the video transmission equipment are respectively connected with different Ethernet interfaces of the SDH equipment through Ethernet, and the voice transmission equipment is connected with an E1 coaxial cable interface of the SDH equipment through an E1 coaxial cable.
The back-end system comprises a back-end switching system, a back-end control system and a back-end SDH system, wherein the back-end control system comprises one or more of a management computer, video monitoring equipment and voice switching equipment, the management computer is connected with the back-end switching system through Ethernet, the back-end switching system is connected with the back-end SDH system through Ethernet, the video monitoring equipment is connected with different Ethernet interfaces of the SDH equipment through Ethernet, and the voice switching equipment is connected with E1 coaxial cable interfaces of the SDH equipment through E1 coaxial cables.
The front-end SDH system of the system comprises two SDH devices connected by optical fibers, wherein SDH A devices are main devices, SDH B devices are redundant standby devices, the back-end SDH system also comprises two SDH devices connected by optical fibers, SDH D devices are main devices, SDH C devices are redundant standby devices, SDH A devices and SDH D devices are interconnected by optical fibers smaller than or equal to 40Km and are main links of the front-end system and the back-end system, and SDH B devices and SDH C devices are also interconnected by optical fibers smaller than or equal to 40Km and are redundant standby links of the front-end system and the back-end system. The front end and the back end of the 4 SDH devices form an SDH redundant communication network of the system.
The SDH equipment comprises an FPGA (field programmable gate array) module and a CPU (central processing unit) control module, wherein an E1 interface chip is provided with an 8-path E1 coaxial cable interface, an Ethernet physical layer chip is connected with an 8+1-path Ethernet interface, an E1 mapping module is connected with the E1 interface chip and the Ethernet physical layer chip, an SDH overhead processing module is also connected with a 2-path 2 XSM-16 optical fiber interface, and the E1 mapping module, the Ethernet mapping module and the SDH overhead processing module are all connected to a cross connection unit, and the cross connection unit uniformly performs cross connection processing. The FPGA module is connected with the Ethernet physical layer chip, and the CPU control module is connected with the Ethernet physical layer chip through the switching module.
And a MAC (Medium Access Control meson access control) address learning module is added in the front-end SDH equipment and is connected with an Ethernet physical layer chip.
The control computer at the front end is a double network card, one main and one standby are respectively connected with SDH A and SDH B devices through 2 Ethernet lines.
The management computer at the rear end is a double network card, a main one and a standby one; the back-end switching system comprises a first switch and a second switch, wherein the first switch is a main device, the second switch is a redundant standby device, the first switch and the second switch are connected with each other through the Ethernet, the first switch is connected with an SDH D device through the Ethernet, and the second switch is connected with an SDH C device through the Ethernet and is a redundant standby channel. Two network cards of the management computer at the rear end are respectively connected with the first switch and the second switch through 2 Ethernet lines.
IP data sent by the management computer of the back end is sent to the control computer of the front end through the back end switching system and the Ethernet and the SDH redundant communication network.
The voice exchange equipment at the back end and the voice transmission equipment at the front end are respectively connected with one or more of a hot wire direct-connection telephone line, a common telephone line, a relay line and a magneto telephone at the local end. The voice switching equipment at the back end transmits the voice signals sent by the connected telephone lines to the telephone lines connected by the voice transmission equipment at the front end through the SDH redundant communication network by the E1 coaxial cable.
The video transmission equipment at the front end is connected with the camera and the video playing equipment, the video monitoring equipment at the rear end is connected with the display and the monitor, the video signal sent by the connected video equipment is sent to the video monitoring equipment at the rear end through the SDH redundant communication network by the video transmission equipment at the front end through the Ethernet, and the video signal is displayed on the display and the monitor which are connected with the video transmission equipment at the front end.
In order to ensure that the state information of each interface in the system is quickly and accurately transferred to the whole SDH redundant communication network, each SDH device and other SDH devices are respectively connected through two groups of optical fibers by two paths of optical fiber interfaces.
IP data transmission is carried out between the front-end system and the back-end system through an SDH redundant communication network, and the front-end system receives the audio and video information sent by the back-end system through the SDH redundant communication network.
In order to realize the protection of voice data, the voice switching equipment at the back end and the voice transmission equipment at the front end of the system are respectively connected with an SDH redundant communication network through 2 paths of E1 coaxial cables.
The invention designs a redundancy protection method of a redundancy communication system based on SDH, wherein the principle of selecting a transmission path is that a transmission path with high priority in an SDH redundancy communication network is selected, the priority of a main device and a main link in the SDH redundancy communication network is higher than that of a standby device and a standby link, SDH A and SDH D are main devices, SDH B and SDH C are standby devices, an optical fiber link between SDH A and SDH D is a main link, a front end control system is a P1 node, a rear end control system and a rear end exchange system are P2 nodes, the transmission path between SDH A and P1 nodes is also a main link, SDH A, SDH B, SDH C and SDH D are respectively represented by A, B, C, D, and the default priority ordering of the transmission path in the method is as follows:
P1→A→D→P2＞P1→A→B→C→D→P2＞P1→A→D→C→P2
＞P1→A→B→C→P2＞P1→B→A→D→P2＞P1→B→C→D→P2
＞P1→B→A→D→C→P2＞P1→B→C→P2，
the transmission path of the P1 node and the P2 node connected through the SDH redundant communication network defaults to P1- & gtA- & gtD- & gtP 2.
If the current transmission of the system is smooth or the system fails but does not affect the current data transmission, the system is not switched; if the current data transmission is affected by the occurrence of faults, immediately and simultaneously switching 4 SDH equipment to a path with the highest priority in the available transmission paths of the data after the occurrence of system faults; when the available transmission paths with the priority higher than that of the current transmission path appear after the fault is eliminated, adopting a switching mode, and delaying for 1-3 seconds after the fault is recovered, and simultaneously switching 4 SDH devices to the paths with the highest priorities in the available transmission paths; and if the priority of the available transmission path after the fault elimination is lower than that of the current transmission path, not switching.
And the E1 interface chip of the SDH equipment obtains the states of all E1 interfaces, the link of the Ethernet physical layer chip rapidly detects the states of all interfaces and directly indicates the states, and the SDH overhead processing chip adopts a self-defined overhead byte and detects the states of the optical fiber interfaces through state transition. By detecting each port, whether the transmission path connected with each port is normal or not can be judged. The CPU control module completes the service configuration of the cross connection unit, the switching configuration of the cross connection unit and the selection of a redundant transmission path during the redundant protection, monitors the states of the modules and the chips, and is connected with a monitoring interface for maintenance management. The FPGA module executes a state transfer protection protocol, receives state information of other SDH equipment from each optical fiber interface, judges the current system running state, and detects and reports the current system running state to the CPU control module in real time; meanwhile, the FPGA module sends the running state of the local SDH equipment to all optical fiber interfaces, so that other equipment obtains the state of the equipment to judge the running state of the system and realize line redundancy protection.
In order to realize that the state information of each interface in the system is quickly transferred to the whole SDH redundant communication network and ensure the real-time and accurate state information, each SDH device simultaneously transmits the state information of each interface of the device and forwards the received related information of other SDH devices through two groups of optical fibers by two paths of optical fiber interfaces, and each transmitted interface state information is provided with a special check byte, so that all SDH devices in the SDH redundant communication network within 1ms can acquire the state information of each interface in the whole SDH redundant communication network.
The MAC address learning module added in the front-end SDH equipment intercepts the IP packet sent to the front-end system by the back-end system in real time, decomposes the Ethernet MAC address and the IP address data segment comprising the source address and the target address from the IP packet, establishes a storage area of the Ethernet MAC address at the same time, periodically sends the address learning packet to the back-end switching system, and the back-end switching system can immediately obtain a correct transmission path without address aging time and address learning after receiving the address learning packet, thereby solving the defect of overlong learning time of the switch. The MAC address learning module sends address learning packets to the back-end switching system with a period of 12-18 ms.
In order to realize the protection of voice data, the voice exchange equipment at the back end and the voice transmission equipment at the front end of the system are respectively connected with the SDH redundant communication network through 2 paths of E1 coaxial cables, the method adopts a protection protocol of 'double-sending and optimal receiving', voice signal hot backup of the voice exchange equipment at the back end enters different E1 interfaces of the SDH redundant communication network through two paths of E1 coaxial cables, and the voice data is transmitted to the voice transmission equipment at the front end through different transmission paths in the SDH redundant communication network and then through the two paths of E1 coaxial cables. In order to detect the state of the transmission path, preferred reception at the receiving end, the transmitting end adds overhead content for CRC (Cyclic Redundancy Check ) checksum verification lines in the E1 carrying the voice. The receiving end detects two paths of E1 lines and data at the same time, judges whether the lines are normal or not by detecting the received overhead content, and detects whether the data are normal or not by CRC check. When the lines and data of the two paths E1 are normal, the data is received from the 1 st path by default, and when one path E1 has line or data faults, the data is selected to be received from the correct line.
Compared with the prior art, the SDH-based redundant communication system and the redundant protection method thereof have the beneficial effects that: 1. in the SDH redundant communication network formed by 4 SDH devices, the SDH devices automatically detect the states of all ports and send the states to other devices in the network. When the network link or interface fails, line switching can be completed and data transmission can be restored within 800ms; 2. the 4 SDH devices are switched at the same time, so that the interruption time of the service is reduced, and the normal data transmission can be recovered as long as one transmission path exists between 2 nodes; 3. each transmission path is ordered according to the priority of the main link of the main equipment, when the transmission line fails, the new calculation route is not needed, the switching speed is high, and the recovery of the network is completed within 20 ms; 4. the added MAC address learning module in the SDH equipment intercepts an IP packet sent to the front-end system by the back-end system in real time, decomposes the IP packet to obtain an Ethernet MAC address and an IP address, and periodically sends the address learning packet to the back-end switching system, wherein the time for obtaining the address is less than 3S, and the overlong time for avoiding data loss is avoided; 5. when the SDH equipment is powered off and optical fiber or interface fails, the current transmission path switching and Ethernet service recovery time is 50 ms-800 ms; when a certain SDH device is powered off or an optical fiber fails, the port states of other SDH devices are rapidly detected and rapidly transferred, the SDH redundant communication network immediately switches a new transmission path, and the Ethernet service recovery time under the failure is within 100 ms; when the Ethernet link of the front-end system fails, the front-end control computer has double network cards and double Ethernet lines, and the SDH redundant communication network is immediately switched to other available Ethernet links of the front-end system through the rapid detection and rapid transmission of the port states of the SDH equipment, so that the recovery time of the Ethernet service under the failure is within 300 ms; when the Ethernet link of the back-end system fails, the front-end control computer is provided with a double-network card double-Ethernet line and a main switch and a standby switch, and the SDH redundant communication network is immediately switched to other available Ethernet links of the back-end system through the rapid detection, the rapid transmission and the rapid MAC address learning of the port state of the SDH equipment, and the recovery time of the Ethernet service under the failure is within 800ms; 6. the voice data transmission service is protected by adopting a protection protocol of 'double-sending and excellent-receiving', the same voice signal hot backup is transmitted through two paths E1 via different transmission paths, and even if one path fails, the data can be received from the other correct line.
Drawings
FIG. 1 is a schematic diagram of the overall structure of an embodiment of a SDH-based redundant communication system;
FIG. 2 is a schematic diagram of the structure of an SDH device in an embodiment of a redundant SDH-based communication system;
FIG. 3 is a schematic diagram of the IP data transmission path structure of an embodiment of a redundant SDH-based communication system;
FIG. 4 is a schematic diagram of the transmission path structure of a voice signal of an embodiment of a redundant SDH-based communication system;
FIG. 5 is a schematic diagram of the video signal transmission path structure of an embodiment of a redundant SDH-based communication system;
FIG. 6 is a schematic diagram of switching transmission paths for example 1 of a redundancy protection method embodiment failure of a SDH-based redundancy communication system;
FIG. 7 is a schematic diagram of switching transmission paths for example 2 of a redundancy protection method embodiment failure of a SDH-based redundancy communication system;
fig. 8 is a schematic diagram of transmission path switching in failure example 3 of the embodiment of the redundancy protection method of the SDH-based redundancy communication system.
Detailed Description
SDH-based redundant communication system embodiment
The embodiment of the SDH-based redundant communication system is shown in fig. 1, and comprises a front-end system and a back-end system, wherein the front-end system comprises a front-end control system and a front-end SDH system, the front-end control system comprises one or more of a control computer, video transmission equipment and voice transmission equipment, the control computer and the video transmission equipment are respectively connected with different Ethernet interfaces of the SDH equipment through Ethernet, and the voice transmission equipment is connected with an E1 coaxial cable interface of the SDH equipment through an E1 coaxial cable.
The back-end system comprises a back-end switching system, a back-end control system and a back-end SDH system, wherein the back-end control system comprises one or more of a management computer, video monitoring equipment and voice switching equipment, the management computer is connected with the back-end switching system through Ethernet, the back-end switching system is connected with the back-end SDH system through Ethernet, the video monitoring equipment is connected with different Ethernet interfaces of the SDH equipment through Ethernet, and the voice switching equipment is connected with E1 coaxial cable interfaces of the SDH equipment through E1 coaxial cables.
The front-end SDH system comprises two SDH devices connected by optical fibers, wherein SDH A devices are main devices, SDH B devices are redundant standby devices, and the SDH A devices and the SDH B devices are interconnected by optical fibers through a second path optical fiber interface; the back-end SDH system also comprises two SDH devices connected by optical fibers, wherein the SDH D device is a main device, the SDH C device is a redundant standby device, and the SDH D device and the SDHC device are interconnected by optical fibers through a second path optical fiber interface; SDH A equipment and SDH D equipment are interconnected through optical fibers with the first path of optical fiber interfaces being smaller than or equal to 40Km, and are main links of front-end and back-end systems, and SDH B equipment and SDH C equipment are also interconnected through optical fibers with the first path of optical fiber interfaces being smaller than or equal to 40Km, and are redundant standby links of the front-end and back-end systems. The front end and the back end of the 4 SDH devices form an SDH redundant communication network of the system. In this example, each SDH device is connected to other SDH devices through two sets of optical fibers through two optical fiber interfaces.
As shown in FIG. 2, the SDH device comprises an FPGA module and a CPU control module, wherein an E1 interface chip is provided with an 8-path E1 coaxial cable interface, an Ethernet physical layer chip is connected with an 8+1-path Ethernet interface, an E1 mapping module is connected with the E1 interface chip, the Ethernet mapping module is connected with the Ethernet physical layer chip, an SDH overhead processing module is connected with a 2-path 2×STM-16 optical fiber interface, the E1 mapping module, the Ethernet mapping module and the SDH overhead processing module are all connected with a cross connection unit, and the cross connection unit performs cross connection processing uniformly. The FPGA module is connected with the Ethernet physical layer chip, and the CPU control module is connected with the Ethernet physical layer chip through the switching module.
The front-end SDH equipment is also provided with a MAC address learning module which is connected with an Ethernet physical layer chip.
The control computer at the front end of the embodiment is a double network card, one main and one standby are respectively connected with SDH A and SDH B devices through 2 Ethernet lines.
The management computer at the back end of the embodiment is a double network card, a main one and a standby one; the back-end switching system comprises a first switch and a second switch, wherein the first switch is a main device, the second switch is a redundant standby device, the first switch and the second switch are connected with each other through the Ethernet, the first switch is connected with an SDH D device through the Ethernet, and the second switch is connected with an SDH C device through the Ethernet and is a redundant standby channel. Two network cards of the management computer at the rear end are respectively connected with the first switch and the second switch through 2 Ethernet lines.
As shown in fig. 3, the front-end control system is used as a P1 node, the back-end control system and the back-end switching system are used as P2 nodes, and the IP data sent by the management computer at the back end in this example is sent to the control computer at the front end through the back-end switching system and the ethernet network by SDH a and SDH D of the SDH redundant communication network.
As shown in fig. 4, the voice switching device at the back end and the voice transmission device at the front end of this example are respectively connected to one or more of a hot wire through telephone line, a normal telephone line, a trunk line, and a magneto telephone at the back end. The voice switching equipment at the back end transmits the voice signals sent by the connected telephone lines to the telephone lines connected by the voice transmission equipment at the front end through the SDH redundant communication network by the E1 coaxial cable. The voice switching equipment at the back end and the voice transmission equipment at the front end of the embodiment are respectively connected with the SDH redundant communication network through 2 paths of E1 coaxial cables.
As shown in fig. 5, the video transmission device at the front end of this example is connected to the camera and the video playing device, the video monitoring device at the rear end is connected to the display and the monitor, and the video signal sent by the connected video device is sent to the video monitoring device at the rear end through the SDH redundancy communication network by the video transmission device at the front end via the ethernet, and is displayed on the display and the monitor connected to the video transmission device at the front end.
IP data transmission is carried out between the front-end system and the back-end system through an SDH redundant communication network, and the back-end system receives the audio and video information sent by the front-end system through the SDH redundant communication network.
Redundancy protection method embodiment of SDH-based redundancy communication system
In the embodiment of the redundancy protection method of the SDH-based redundancy communication system, the principle of selecting a transmission path is that a transmission path with high priority in an SDH redundancy communication network is selected, the priority of a main device and a main link in the SDH redundancy communication network is higher than that of a standby device and a standby link, SDH A and SDH D are main devices, SDH B and SDH C are standby devices, an optical fiber link between SDH A and SDH D is a main link, a front-end control system is a P1 node, a rear-end control system and a rear-end exchange system are P2 nodes, SDH A and P1 nodes, the transmission path between SDH D and P2 nodes is also a main link, and SDH A, SDH B, SDH C and SDH D are respectively represented by A, B, C, D, and the default priority ordering of the transmission path in the method is as follows:
P1→A→D→P2＞P1→A→B→C→D→P2＞P1→A→D→C→P2
＞P1→A→B→C→P2＞P1→B→A→D→P2＞P1→B→C→D→P2
＞P1→B→A→D→C→P2＞P1→B→C→P2，
the transmission paths of the P1 node and the P2 node connected via the SDH redundant communication network default to p1→a→d→p2, as shown by the thick solid line in fig. 3.
If the current transmission of the system is smooth or the system fails but does not affect the current data transmission, the system is not switched; if the current data transmission is affected by the occurrence of faults, immediately and simultaneously switching 4 SDH equipment to a path with the highest priority in the available transmission paths of the data after the occurrence of system faults; when the available transmission paths with the priority higher than that of the current transmission path appear after the fault is eliminated, adopting a switching mode, delaying for 2 seconds after the fault is recovered, and simultaneously switching 4 SDH devices to the path with the highest priority in the available transmission paths; and if the priority of the available transmission path after the fault elimination is lower than that of the current transmission path, not switching.
And the E1 interface chip of the SDH equipment obtains the states of all E1 interfaces, the link of the Ethernet physical layer chip rapidly detects the states of all interfaces and directly indicates the states, and the SDH overhead processing chip adopts a self-defined overhead byte and detects the states of the optical fiber interfaces through state transition. By detecting each port, whether the transmission path connected with each port is normal or not can be judged. The CPU control module completes the service configuration of the cross connection unit, the switching configuration of the cross connection unit and the selection of a redundant transmission path during the redundant protection, monitors the states of the modules and the chips, and is connected with a monitoring interface for maintenance management. The FPGA module executes a state transfer protection protocol, receives state information of other SDH equipment from each optical fiber interface, judges the current system running state, and detects and reports the current system running state to the CPU control module in real time; meanwhile, the FPGA module sends the running state of the local SDH equipment to all optical fiber interfaces, so that other equipment obtains the state of the equipment to judge the running state of the system and realize line redundancy protection.
In the embodiment, each SDH device transmits the state information of each interface of the device and forwards the received related information of other SDH devices through two groups of optical fibers through two paths of optical fiber interfaces, and each transmitted interface state information is provided with a special check byte, so that all SDH devices in the SDH redundant communication network within 1ms can acquire the state information of each interface in the whole SDH redundant communication network.
The MAC address learning module added in the front-end SDH equipment intercepts the IP packet sent to the front-end system by the back-end system in real time, decomposes the Ethernet MAC address and the IP address data segment comprising the source address and the target address from the IP packet, establishes the storage area of the Ethernet MAC address at the same time, periodically sends the address learning packet to the back-end switching system, and the back-end switching system can immediately obtain a correct transmission path without address aging time and address learning, thereby solving the defect of overlong learning time of the switch. The MAC address learning module sends address learning packets to the back-end switching system with a period of 12-18 ms.
The method adopts a protection protocol of 'double-sending and excellent-receiving', a voice signal hot backup of a voice exchange device at the rear end enters different E1 interfaces of an SDH redundant communication network through two paths of E1 coaxial cables, and voice data is transmitted to a voice transmission device at the front end through different transmission paths in the SDH redundant communication network through the two paths of E1 coaxial cables. In order to detect the state of the transmission path and preferentially receive at the receiving end, the sending end adds the overhead content for CRC check and verification lines in the E1 carrying the voice. The receiving end detects two paths of E1 lines and data at the same time, judges whether the lines are normal or not by detecting the received overhead content, and detects whether the data are normal or not by CRC check. When the lines and data of the two paths E1 are normal, the data is received from the 1 st path by default, and when one path E1 has line or data faults, the data is selected to be received from the correct line.
The following is a case of switching lines when several faults occur in the embodiment of the redundancy protection method of the SDH-based redundancy communication system.
Failure example 1
As shown in fig. 6, the original transmission paths are P1-a-D-P2, the optical fiber faults between the devices SDH a and SDH D are detected from the optical fiber interfaces, the FPGA modules of the two devices send the faults to the CPU modules of the device, and simultaneously send the faults to the other three SDH devices, the CPU modules of the 4 SDH devices judge that the available transmission paths have P1-a-B-C-D-P2, P1-a-B-C-P2, P1-B-C-D-P2, P1-B-C-P2, and select the P1-a-B-C-D-P2 with the highest priority, as shown by the bold line in fig. 6, the four SDH devices switch simultaneously: the Ethernet service of the SDH A is switched from the optical fiber port transmission connected with the SDH D to the optical fiber port transmission connected with the SDH B, the Ethernet service of the SDH D is switched from the optical fiber port transmission connected with the SDH A to the optical fiber port transmission connected with the SDH C, the Ethernet service transparent transmission channels of the SDH B and the SDH C are established, and the test tests prove that the service recovery time of redundancy protection under the fault is within 20 ms.
Failure example 2
As shown in fig. 7, the original transmission path is P1-a-D-P2, the ethernet link between the devices SDH a and P1 is failed, the SDH a detects the ethernet link failure between the two from the ethernet interface, the FPGA module sends the failure to the CPU module of the device, and simultaneously sends the failure to the other three SDH devices, the CPU modules of the 4 SDH devices determine that the available transmission paths have P1-B-a-D-P2, P1-B-C-D-P2, P1-B-a-D-C-P2, P1-B-C-P2, and the service recovery time of the redundancy protection under the failure is tested to be within 800ms, as shown by the bold line in fig. 7.
Failure example 3:
as shown in fig. 8, the original transmission path is P1-a-D-P2, the device SDH D is powered off, SDH a and SDH C detect SDH D faults from the optical fiber interface, the FPGA modules of SDH a and SDH C send the faults to the CPU modules of the device, and simultaneously send the faults to the other three SDH devices, the CPU modules of the 4 SDH devices judge that the available transmission paths have P1-a-B-C-P2 and P1-B-C-P2, and select P1-a-B-C-P2 with high priority, as shown by the bold line in fig. 8, the four SDH devices are switched simultaneously, and the service recovery time of redundancy protection under the fault is tested to be within 50 ms.
The above embodiments are merely specific examples for further detailed description of the object, technical solution and advantageous effects of the present invention, and the present invention is not limited thereto. Any modification, equivalent replacement, improvement, etc. made within the scope of the present disclosure are included in the scope of the present invention.
Claims (10)
1. The SDH-based redundant communication system comprises a front-end system and a back-end system, wherein the front-end system comprises a front-end control system and a front-end SDH system, the front-end control system comprises one or more of a control computer, video transmission equipment and voice transmission equipment, the control computer and the video transmission equipment are respectively connected with different Ethernet interfaces of the SDH equipment through Ethernet, and the voice transmission equipment is connected with an E1 coaxial cable interface of the SDH equipment through an E1 coaxial cable;
the back-end system comprises a back-end switching system, a back-end control system and a back-end SDH system, wherein the back-end control system comprises one or more of a management computer, video monitoring equipment and voice switching equipment, the management computer is connected with the back-end switching system through an Ethernet, the back-end switching system is connected with the back-end SDH system through the Ethernet, the video monitoring equipment is connected with different Ethernet interfaces of the SDH equipment through the Ethernet, and the voice switching equipment is connected with an E1 coaxial cable interface of the SDH equipment through an E1 coaxial cable; the method is characterized in that:
the front-end SDH system comprises two SDH devices connected by optical fibers, wherein SDH A devices are main devices, SDH B devices are redundant standby devices, the back-end SDH system also comprises two SDH devices connected by optical fibers, SDH D devices are main devices, SDH C devices are redundant standby devices, SDH A devices and SDH D devices are interconnected by optical fibers smaller than or equal to 40Km and are main links of the front-end system and the back-end system, and SDH B devices and SDH C devices are also interconnected by optical fibers smaller than or equal to 40Km and are redundant standby links of the front-end system and the back-end system; the front end and the back end of the 4 SDH devices form an SDH redundant communication network of the system;
the SDH equipment comprises an FPGA module and a CPU control module, wherein an E1 interface chip is provided with an 8-path E1 coaxial cable interface, an Ethernet physical layer chip is connected with an 8+1-path Ethernet interface, an E1 mapping module is connected with the E1 interface chip, an Ethernet mapping module is connected with the Ethernet physical layer chip, an SDH overhead processing module is also connected with a 2-path 2×STM-16 optical fiber interface, the E1 mapping module, the Ethernet mapping module and the SDH overhead processing module are all connected to a cross connection unit, and the cross connection unit uniformly performs cross connection processing; the FPGA module is connected with the Ethernet physical layer chip, and the CPU control module is connected with the Ethernet physical layer chip through the switching module.
2. The SDH-based redundant communication system of claim 1 wherein:
and a MAC address learning module is added in the front-end SDH equipment and is connected with an Ethernet physical layer chip.
3. The SDH-based redundant communication system of claim 1 wherein:
the control computer at the front end is a double network card, one main and one standby are respectively connected with SDH A and SDH B equipment through 2 Ethernet lines;
the management computer at the rear end is a double network card, a main one and a standby one; the back-end switching system comprises a first switch and a second switch, wherein the first switch is a main device, the second switch is a redundant standby device, the first switch and the second switch are connected with each other through the Ethernet, the first switch is connected with an SDH D device through the Ethernet, and the second switch is connected with an SDH C device through the Ethernet and is a redundant standby channel. Two network cards of the management computer at the rear end are respectively connected with the first switch and the second switch through 2 Ethernet lines.
4. The SDH-based redundant communication system of claim 1 wherein:
and each SDH device in the SDH redundant communication network is connected with other SDH devices through two groups of optical fibers through two paths of optical fiber interfaces.
5. A redundancy protection method for an SDH-based redundant communication system according to any one of claims 1 to 4, characterized by:
the principle of selecting a transmission path is to select a transmission path with high priority in an SDH redundant communication network, the priority of a main device and a main link in the SDH redundant communication network is higher than that of a standby device and a standby link, SDH A and SDH D are main devices, SDH B and SDH C are standby devices, an optical fiber link between SDH A and SDH D is a main link, a front-end control system is a P1 node, a back-end control system and a back-end switching system are P2 nodes, SDH A and P1 nodes, the transmission path between SDH D and P2 nodes is also a main link, SDH A, SDH B, SDH C and SDH D are respectively represented by A, B, C, D, and the default priority ordering of the transmission path in the method is as follows:
P1→A→D→P2＞P1→A→B→C→D→P2＞P1→A→D→C→P2
＞P1→A→B→C→P2＞P1→B→A→D→P2＞P1→B→C→D→P2
＞P1→B→A→D→C→P2＞P1→B→C→P2，
the transmission path of the P1 node and the P2 node connected through the SDH redundant communication network defaults to P1- & gtA- & gtD- & gtP 2.
6. The redundancy protection method for an SDH-based redundant communication system of claim 5 wherein:
if the current transmission of the system is smooth or the system fails but does not affect the current data transmission, the system is not switched; if the current data transmission is affected by the occurrence of faults, immediately and simultaneously switching 4 SDH equipment to a path with the highest priority in the available transmission paths of the data after the occurrence of system faults; when the available transmission paths with the priority higher than that of the current transmission path appear after the fault is eliminated, delay is carried out for 1-3 seconds and 4 SDH devices are simultaneously switched to the path with the highest priority in the available transmission paths after the fault is recovered; and if the priority of the available transmission path after the fault elimination is lower than that of the current transmission path, not switching.
7. The redundancy protection method for an SDH-based redundant communication system of claim 5 wherein:
the E1 interface chip of the SDH equipment obtains the states of all E1 interfaces, the link of the Ethernet physical layer chip rapidly detects the states of all interfaces and directly indicates the states, the SDH overhead processing chip adopts a self-defined overhead byte, and the states of the optical fiber interfaces are detected through state transition; the CPU control module completes the service configuration of the cross connection unit, the switching configuration of the cross connection unit and the selection of a redundant transmission path during the redundant protection, monitors the states of the modules and the chips, and is connected with a monitoring interface for maintenance management; the FPGA module executes a state transfer protection protocol, receives state information of other SDH equipment from each optical fiber interface, judges the current system running state, and detects and reports the current system running state to the CPU control module in real time; and simultaneously, the FPGA module transmits the running state of the local SDH equipment to all optical fiber interfaces.
8. The redundancy protection method for an SDH-based redundant communication system of claim 7 wherein:
and each SDH device transmits the interface state information of the device through two groups of optical fibers through two paths of optical fiber interfaces and forwards the received related information of other SDH devices, and each transmitted interface state information is provided with a special check byte.
9. The redundancy protection method for an SDH-based redundant communication system of claim 5 wherein:
and a MAC address learning module is added in the front-end SDH equipment, the module intercepts an IP packet sent to the front-end system by the back-end system in real time, decomposes an Ethernet MAC address and an IP address data segment comprising a source address and a target address from the IP packet, establishes a storage area of the Ethernet MAC address, and periodically sends the address learning packet to the back-end switching system.
10. The redundancy protection method for an SDH-based redundant communication system of claim 5 wherein:
the method adopts a protection protocol of 'double-sending and optimal receiving', voice signal hot backup of the voice exchange equipment at the rear end enters different E1 interfaces of the SDH redundant communication network through two paths of E1 coaxial cables, and voice data is transmitted to the voice transmission equipment at the front end through different transmission paths in the SDH redundant communication network and then through two paths of E1 coaxial cables;
the sending end adds the overhead content for CRC check and verification line in E1 bearing voice; the receiving end detects two paths of E1 lines and data at the same time, judges whether the lines are normal or not by detecting the received overhead content, and detects whether the data are normal or not by CRC check; when the lines and data of the two paths E1 are normal, the data is received from the 1 st path by default, and when one path E1 has line or data faults, the data is selected to be received from the correct line.
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