CN1445956A - Dynamic multiple wavelength grouping ring transmission system - Google Patents

Abstract

A dynamic multi-wavelength packet ring transmission system consists of an electrical layer subsystem and an optical layer subsystem. The electrical layer subsystem includes a line receiving module, a line sending module, and a packet switching module. The optical layer subsystem includes an optical layer protection switching module, an optical amplifier, and an optical add/drop multiplexer/demultiplexer. The line receiving/transmitting module completes the adaptation and conversion of electrical layer and optical layer signals. The packet switching module performs Layer 2 or Layer 3 switching and then transmits the data to the line sending module. The optical layer protection switching module implements the optical layer group signal. Fast protection switching, optical add-drop multiplexing module realizes dynamic add-drop function and bypass function for each wavelength channel. The invention integrates the characteristics of large capacity and dynamic reconfiguration of the optical layer network into the traditional packet ring system, so that the packet ring system has better network expansibility to adapt to large-scale network applications.

Description

Dynamic multi-wavelength packet ring transmission system

Technical field:

The present invention relates to a dynamic multi-wavelength packet ring transmission system. In the traditional elastic packet ring system, wavelength division multiplexing technology (WDM) is combined to increase the wavelength dynamic bypass function of the optical layer subsystem, so that the elastic packet ring system has good network expansion capabilities. The invention belongs to the technical field of broadband communication network.

Background technique:

With the rapid growth of Internet services, the construction of a new generation of broadband metropolitan area network to meet the needs of future network development has become a hot spot for investment in the telecommunications sector. In the construction of the broadband metropolitan area network, various solutions emerge, among which, the RPR (Resilient Packet Ring) solution being standardized by the IEEE802.17 working group is highly expected due to its unique advantages.

RPR defines a new MAC (Media Access Control) protocol to optimize packet transmission in LAN (Local Area Network), MAN (Metropolitan Area Network) and WAN (Wide Area Network) ring topologies. In RPR, space reuse protocol (SRP) and intelligent protection switching mechanism are adopted, which not only greatly improves the bandwidth efficiency of the network, but also realizes fast service protection switching of less than 50ms. In addition, RPR also provides a very simple service model, which further simplifies service provision.

The RPR protocol actually combines the advantages of Ethernet and Synchronous Digital Transmission Network (SDH), trying to provide users with SDH-like service quality at the cost of Ethernet. Therefore, in the construction climax of the current construction of broadband metropolitan area network, RPR has received special attention.

However, in the traditional RPR system, the dual-ring structure adopted by RPR requires each node in the ring to terminate the transmission link on the electrical layer, which means that for each logical ring on the ring (using WDM When using transmission, each wavelength channel constitutes a logical ring, and there are multiple logical rings on a physical ring), and each node needs corresponding transceivers and processing capabilities to process the data transmitted on the logical ring, even if the nodes are not connected Packet data is not sent to and from this logical ring.

For this structure, there is no problem when the network has only one logical ring (using single-fiber single-wavelength links), however, when the network has multiple logical rings (using single-fiber multi-wavelength links or Fiber single-wavelength links), the scalability of the network is greatly limited. At present, the maximum transmission capacity of a single wavelength is only 40Gbps. If a network with a capacity greater than 40G needs to be constructed, multi-fiber or multi-wavelength transmission methods have to be used to form multiple logical ring structures on a physical ring. In fact, in the core network of the metropolitan area, the network capacity often requires tens of gigabytes or even hundreds of gigabytes.

For such a network with multiple logical rings, the services of certain nodes in the network are often transmitted on one or several logical rings. Therefore, in fact, these nodes only need to terminate and process information contained in the electrical domain. The logical ring of this node is sufficient, and all logical rings do not need to be terminated and processed. However, in a traditional packet ring system, each node on the ring is required to terminate and process all logical rings. The problem brought about by this is that if a certain core network must have the capacity of N wavelengths to support, then each node in the ring network must have N optical transceivers and support N wavelengths in each direction. Capacity data processing capability, even if the actual access traffic of a certain node is very small (such as in the HUB business model). There is no doubt that the cost of using this structure to build a large-capacity network is quite large, and it is actually not practical.

Moreover, this structure also brings another problem. When the network has multiple logical rings and the number of nodes in the ring is considerable (such as dozens), since the packets are forwarded point by point through each intermediate node, the accumulated forwarding The time delay is considerable, especially when a network failure requires protection switching and detour transmission.

According to the above analysis, the existing packet ring transmission system has limitations in network scalability, and the disadvantages are especially obvious when the network scale increases.

Invention content:

The purpose of the present invention is to propose a dynamic multi-wavelength packet ring transmission system to improve the network expansion capability of the packet ring transmission system, so that it can be applied to the core network of the metropolitan area.

In order to achieve this purpose, the present invention adopts wavelength division multiplexing technology (WDM) and wavelength add-drop multiplexing (OADM) technology according to the huge bandwidth and reconfigurable characteristics of the optical layer network, organically combining it with the traditional elastic packet ring system Combine. For this reason, the present invention superimposes an optical layer subsystem on the basis of the traditional electrical layer packet ring system, and the optical layer subsystem forms an optical layer subnetwork through networking. In the optical layer sub-network, according to the distribution of traffic, different wavelength channels divide network nodes into different node groups, and each node group shares one of the wavelengths to form a logical packet ring. For each logical packet ring, the nodes belonging to the logical ring first add and drop the wavelengths of the node in the optical layer subnetwork, and then terminate and perform packet forwarding processing on the electrical domain. The ring system is the same. For the wavelength channels that do not belong to the logical ring, the node performs optical bypass on these wavelengths directly on the optical layer, instead of terminating and processing them on the electrical domain.

In addition, the present invention also considers that when an optical fiber link failure or node failure occurs, the affected services and nodes must perform protection switching processing, and if there are multiple logical grouping rings, each logical ring must perform separate protection switching operation, network performance will be greatly affected. For this reason, the present invention provides the protection switching function on the optical layer, realizes the fast protection switching of optical layer group signal, when a single link or node failure occurs, only need to carry out the protection switching operation on two nodes, without having to Each logical grouping ring performs independent protection switching.

According to the above idea, the technical solution of the present invention divides the proposed dynamic multi-wavelength packet ring system into two subsystems: an optical layer subsystem and an electrical layer subsystem. Among them, the optical layer subsystem includes an optical layer protection switching module, an optical amplifier, and an optical add-drop multiplexer. The electrical layer subsystem includes a line receiving module, a line sending module, and a packet switching module. The optical layer protection switching module passes the internal optical layer composite signal Connected with the optical add-drop multiplexer, the optical add-drop multiplexer is connected with the line receiving module of the electrical layer subsystem through the drop wavelength signal, the line receiving module is connected with the packet switching module through the internal interface, and the output of the packet switching module is connected to Line transmission module, the output of the line transmission module is connected to the optical add-drop multiplexer through the add wavelength signal, the optical add-drop multiplexer is connected to the input end of the optical amplifier through the internal optical layer composite signal, and the output end of the optical amplifier is connected to the optical layer The protection switching modules are connected.

The optical layer group signal first enters the optical layer protection switching module from the receiving link, and then connects to the optical add-drop multiplexer, and the drop wavelength signal from the add-drop multiplexer enters the electrical layer through the line receiving module In the system, the packets from each line receiving unit then enter the packet switching unit for switching, and the switched packets are processed by the line sending module to form an uplink wavelength signal, which is connected to the optical add-drop multiplexer and inserted into the optical layer composite signal. , the optical layer composite signal output by the optical add-drop multiplexer enters the optical amplifier for amplification, and the amplified output signal is connected to the optical layer protection switching module, and the optical layer protection switching module outputs the optical layer group circuit signal to the transmission link.

The optical layer subsystem and the electrical layer subsystem are connected through an internal wavelength add/drop interface. The optical layer protection switching module realizes the fast protection switching of the optical layer group signal. The optical layer group signal from the receiving link enters the optical add-drop multiplexer module after passing through the optical layer protection switching module, and the optical add-drop multiplexer module realizes dynamic add-drop function and bypass function for each wavelength channel. On a logical ring, the network nodes belonging to the logical ring take out the wavelength channel through the optical add-drop multiplexing module, terminate the wavelength in the electrical domain, and then forward and process the packet service carried by the wavelength. At the same time, the node modulates the processed service to be transmitted to the next node on the logical ring onto the wavelength channel, and inserts the wavelength channel into the wavelength division multiplexing signal through the optical add-drop module. For other wavelength channels that do not belong to the logical ring, the node directly bypasses them through the optical add-drop module. The line receiving/transmitting module implements the functions stipulated by IEEE802.17 like the traditional packet ring system, and at the same time completes the adaptation and conversion of electrical layer signals and optical layer signals. The packet switching module performs Layer 2 or Layer 3 switching on the packets from the line receiving module, and transmits the switched data to the line sending module.

According to the present invention, for a specific wavelength channel, because it is directly bypassed on the optical layer at some intermediate nodes, the virtual elastic packet ring sub-network formed by this wavelength channel is actually only composed of a small number of nodes , the network scale of the sub-network can be reduced, so the performance of the network delay and throughput can be improved. For nodes with less traffic, it is only necessary to terminate the wavelength channel for transmitting local node services, and other wavelength channels directly pass through the optical layer bypass, so each node in the network can configure line interfaces according to its own traffic requirements card and switching capacity, thereby reducing network costs.

In summary, the present invention integrates the characteristics of large capacity and dynamic reconfiguration of the optical layer network into the traditional packet ring system, so that the packet ring system has better network scalability to adapt to large-scale network applications . Compared with the traditional grouping ring system, it has remarkable features and progress, which are embodied in: ●Dynamic logical grouping ring construction function. By stacking optical layer subsystems, multiple nodes can dynamically select a certain wavelength to form a logical ring to adapt to changes in network service distribution. ●Fast group signal protection switching function. Since the fast protection switching of the optical layer group signal is realized on the optical layer, when a link or node failure occurs, each logical packet ring does not need to perform a separate protection switching operation, thereby reducing the influence of the failure. ●Economic network construction cost. Due to the realization of dynamic wavelength bypass on the optical layer, nodes do not need to terminate and forward each wavelength in the electrical domain, which reduces the number of line cards and the switching capacity of the network. ● Smaller forwarding delay. Through the dynamic bypass of the optical layer, the packets only need to be forwarded by the intermediate nodes between the source and sink nodes on the logical ring, instead of all the intermediate nodes between the source and sink nodes on the physical ring, so the forwarding delay is shorter.

Description of drawings:

Fig. 1 is a schematic block diagram of the node structure of the system of the present invention.

In Figure 1, λ ₁ ..λ _i ..λ _j ..λ _n represent multi-wavelength group signal, OPSM represents optical layer protection switching module, OA represents optical amplifier, OADM represents optical add-drop multiplexer, Tx represents line Transmitting module, Rx represents the line receiving module, PSM represents the packet switching module, λ _i represents a single wavelength channel drop signal, and λ _j represents a single wavelength channel add signal.

Fig. 2 is a network structure block diagram formed by applying the present invention.

Fig. 3 is a block diagram of a node structure of an embodiment of the present invention.

In Fig. 3, OSW is a 2x2 optical switch, MUX is a wavelength division multiplexer, and DEMUX is a wavelength division multiplexer.

Detailed ways:

In order to better understand the technical solution of the present invention, a detailed description is given below in conjunction with the accompanying drawings and embodiments. The figures and examples do not imply a limitation of the invention.

Fig. 1 is a schematic block diagram of the node structure of the system of the present invention. The node is composed of an optical layer subsystem and an electrical layer subsystem. The optical layer subsystem includes an optical layer protection switching module (OPSM), an optical amplifier (OA) and an optical add-drop multiplexer (OADM). The electrical layer subsystem includes a line receiving module. (Rx), Line Transmit Module (Tx) and Packet Switch Module (PSM). The optical layer group signal (λ ₁ ..λ _i ..λ _j ..λ _n ) first enters the optical layer protection switching module (OPSM) from the receiving link, and then connects with the optical add-drop multiplexer (OADM), The drop wavelength signal (λ _i ) dropped from the add-drop multiplexer enters the electrical layer subsystem through the line receiving module (Rx), and the packets from each line receiving module (Rx) then enter the packet switching unit (PSM) for further processing. Switching, the switched packets are processed by the line transmission module (Tx) to form an add wavelength signal (λ _j ), and λ _j is connected to an optical add-drop multiplexer (OADM) and inserted into the optical layer composite signal. The optical layer composite signal output by the add-drop multiplexer (OADM) enters the optical amplifier (OA) for amplification, and the output signal amplified by the optical amplifier (OA) is connected to the optical layer protection switching module (OPSM), and the optical layer protection switching module ( OPSM) outputs the optical layer group signal (λ ₁ ..λ _i ..λ _j ..λ _n ) to the sending link.

Fig. 2 is a network structure block diagram formed by applying the present invention. In the figure, multiple nodes are interconnected by optical fibers to form a two-fiber bidirectional ring network. Each wavelength channel in the WDM link forms a logical packet ring. Different node components belong to different logical packet rings, forming a dynamic multiple Wavelength packet ring transmission system.

Fig. 3 is a block diagram of a node structure of an embodiment of the present invention. The node is composed of an optical layer subsystem and an electrical layer subsystem. The optical layer subsystem includes an optical layer protection switching module (OPSM), an optical amplifier (OA) and an optical add-drop multiplexer (OADM). The electrical layer subsystem includes a line receiving module. (Rx), Line Transmit Module (Tx) and Packet Switch Module (PSM). The optical layer protection switching module (OPSM) uses two 2x2 optical switches OSW to connect the optical layer group signal as shown in the figure. The Optical Add-Drop Multiplexer (OADM) is realized by a wavelength division multiplexer (MUX)/demultiplexer (DEMUX) and a 2x2 optical switch (OSW) array.

In Figure 3, the optical layer group signal (λ ₁ ..λ _i ..λ _j ..λ _n ) first enters an input of the 2x2 optical switch (OSW) in the optical layer protection switching module (OPSM) from the receiving link end, and then connected to the wave division multiplexer (DEMUX) in the optical add-drop multiplexer (OADM) at an output end of the optical switch (OSW), and the multiple wavelengths decomposed by the wave division multiplexer (DEMUX) The channel signals are respectively connected to one input terminal of their own 2x2 optical switch (OSW), one output terminal of the 2x2 optical switch (OSW) connects the bypass signal to the wavelength division multiplexer (MUX), and the other output terminal The downlink wavelength signal (λ _i ) is connected to the line receiving module (Rx) in the electrical layer subsystem, and the packets from each line receiving module (Rx) then enter the packet switching unit (PSM) for switching, and the switched packets The uplink wavelength signal (λ _j ) is formed after being processed by the line transmission module (Tx), and the uplink wavelength signal (λ _j ) is connected to an input terminal of a 2x2 optical switch (OSW) in the optical add-drop multiplexer (OADM), and the wavelength The optical layer composite signal output by the demultiplexer (MUX) enters the optical amplifier (OA) for amplification, and the output signal amplified by the optical amplifier (OA) is connected to the 2x2 optical switch (OSW) in the optical layer protection switching module (OPSM) At one input end, the optical layer protection switching module (OPSM) outputs the optical layer group signal (λ ₁ ..λ _i ..λ _j ..λ _n ) to the transmission link.

In the optical layer protection switching module (OPSM), usually, the two optical switches are in the "straight-through" state. When the upstream optical fiber link or node fails, the corresponding optical switch is set to the "crossover" state, thereby realizing The transmission signal is looped back to achieve the purpose of protection switching.

In the optical add-drop multiplexer (OADM), the optical layer group signal from the optical layer protection switching module first enters the wavelength division multiplexer (DEMUX), and the wavelength division multiplexer (DEMUX) decomposes the composite signal into individual The wavelength channel signal, the decomposed wavelength channel signal and the add/drop wavelength channel signal are connected to a 2x2 optical switch (OSW) as shown in the figure. If the node does not belong to the logical packet ring of a certain wavelength channel, the optical switch (OSW) is in the "through" state, and the wavelength channel is directly bypassed on the optical layer and no longer enters the electrical layer switch; if the node Belonging to a logical packet ring of a wavelength channel, the optical switch (OSW) is in the "crossover" state, and the wavelength channel is dropped to the electrical layer subsystem for further processing. At the same time, the added wavelength from the electrical layer subsystem channel signal is routed. The bypassed and added wavelength channels are multiplexed into an optical layer group signal through a wavelength division multiplexer (MUX) and then enter the optical amplifier (OA).

The optical amplifier (OA) performs all-optical amplification on the optical layer group signal from the optical add-drop multiplexer to compensate for the optical power loss caused by line transmission and node add-drop operation. The output signal of the optical amplifier (OA) enters the optical layer protection switching module (OPSM), and then is output to the transmission link.

The line receiving module Rx terminates the downlink wavelength channel signal (λ _i ) from the optical add-drop multiplexer (OADM), and processes it according to the IEEE802.17 specification. The data packet enters the packet switching module (PSM) and the packet from other ports Switching is performed, and the switched packets are processed by the line transmission module (Tx) according to the IEEE802.17 specification to form an uplink wavelength channel signal (λ _j ), and then enter the optical layer subsystem.

Claims (2)

1. A dynamic multi-wavelength packet ring transmission system, comprising a line receiving module (Rx), a line sending module (Tx) and a packet switching module (PSM) in the electric layer subsystem, is characterized in that on the basis of the electric layer subsystem An optical layer subsystem is superimposed, and the optical layer subsystem includes an optical layer protection switching module (OPSM), an optical amplifier (OA) and an optical add-drop multiplexer (OADM). The optical layer protection switching module (OPSM) passes the internal optical layer composite signal It is connected to the optical add-drop multiplexer (OADM), and the optical add-drop multiplexer (OADM) is connected to the line receiving module (Rx) of the electrical layer subsystem through the drop wavelength signal (λ _i ), and the line receiving module (Rx) It is connected to the packet switching module (PSM) through the internal interface, the output of the packet switching module is connected to the line transmission module (Tx), and the output of the line transmission module ( _Tx ) is connected to the optical add-drop multiplexer ( OADM), the optical add-drop multiplexer (OADM) is connected to the input end of the optical amplifier (OA) through the internal optical layer composite signal, and the output end of the optical amplifier (OA) is connected to the optical layer protection switching module (OPSM). 2. The dynamic multi-wavelength packet ring transmission system according to claim 1, characterized in that: the add/drop wavelengths between the electrical layer subsystem and the optical layer subsystem are dynamically configured by the optical layer subsystem, each on the ring Each wavelength channel constitutes a logical packet ring, and the nodes that add and drop to this wavelength channel are part of the logical packet ring. Different node groups form multiple different logical packet rings. The working principle of each logical packet ring follows IEEE802.17 standard.

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