WO2011116596A1

WO2011116596A1 - Method for calculating multiplexing routing based on g.709 and path calculation device

Info

Publication number: WO2011116596A1
Application number: PCT/CN2010/077026
Authority: WO
Inventors: 付锡华; 张新灵
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-03-25
Filing date: 2010-09-17
Publication date: 2011-09-29
Also published as: CN102201972B; CN102201972A

Abstract

The present invention provides a method for calculating multiplexing routing based on G.709, which is applied to an optical transport network including gateway network elements, and the method includes: a path calculation unit acquires multi stages multiplexing capabilities supported by gateway network elements; and when receiving an end-to-end path calculation request of a path calculation client, the path calculation unit calculates the end-to-end routing according to the acquired multi stages multiplexing capabilities supported by the gateway network elements, and determines the gateway network elements passed by the end-to-end routing and the multi stages multiplexing capabilities selected for the passed gateway network elements. The method for calculating multiplexing routing and a path calculation device implement the calculation for the end-to-end multi stages multiplexing routing, and thereby lay the foundation for implementing inter-connection and inter-communication between networks.

Description

G.709-based multiplexing route calculation method and path calculation device

Technical field

The invention belongs to the field of optical network transmission, and in particular relates to a G.709-based multiplexing route calculation method and a path calculation device in an optical transmission network automatic switching optical network.

Background technique

Optical Transport Network (OTN) is a "digital encapsulation" technology proposed in 1999 to solve the problem of high-capacity transmission of high-speed Time Division Multiplexing (TDM) signals. The OTN defined in the 2003 version provides functions such as transmission, multiplexing, protection, and monitoring management for the client layer signals. The supported client layer signals are mainly STM-N (synchronous transmission mode), ATM (asynchronous transmission mode), and GFP (through GFP ( Universal framing program) Maps supported Ethernet signals with defined rate classes of 2.5G, 10G and 40G. With the IP of the bearer signal of the transport network and the popularity of the 10G LAN interface, the bearer of 10GE (10 Gigabit Ethernet) on the OTN has become an important issue. Therefore, the International Telecommunication Union (ITU-T) developed G. in 2007. The 709 supplemental standard (G.sup43) defines the way OTN transmits 10GE signals.

The traditional OTN multiplexing system is very simple, with speed classes of 2.5G, 10G and 40G, corresponding to optical channel data units ODU1, ODU2 and ODU3, respectively. The CBR (Constant Bit Rate) service is mapped to the corresponding ODUk by means of asynchronous mapping (AMP) or bit synchronization mapping (BMP), and the packet (packet) service is mapped to ODUk by GFP, and these ODUk are remapped. Go to the corresponding optical channel transmission unit OTUk. Of course, low-rate ODUs can also be reused in high-rate ODUs, as shown in Figure 1.

In order to adapt to multi-service, OTN introduces a new concept HO (High Order) ODU and LO (Low Order) ODU, as shown in Figure 2, from the left in Figure 2, the first column is LO ODU, the rate level in each box, such as ODU3, is marked as ODU3 (L), L is Low Order; the second column is high-order, the rate level in each box, such as ODU3, is marked as ODU3 ( H), H is High Order. HO/LO is consistent with the concept of high-order/low-order containers in SDH. LO ODU is equivalent to the service layer used to adapt services of different rates and different formats. HO ODU is equivalent to the tunnel layer used to provide certain bandwidth transmission. Ability, this hierarchical structure supports the industry The service card is separated from the circuit board card, which brings greater flexibility and economy to the network deployment.

G.709 Amendment 3 and G.sup 43 have changed a lot compared to G.709 in 2003. It introduces new signal types, including ODU0, ODU2e, ODU3el, ODU3e2, and flexible ODU ( ODUflex ) and ODU4. First, a new optical channel data unit ODU0 with a rate of 1.244 Gb/s is introduced. The ODU0 can be independently cross-connected or mapped to higher-order ODUs (such as ODU1, ODU2, ODU3, and ODU4). In order to accommodate the transmission of the upcoming 100GE service, ODU4 was introduced at a rate of 104.355 Gb/s.

ODU1 is mapped to ODU2, ODU3, and ODU2 is mapped to ODU3 to maintain the original G.709 version of the 2.5G tributary timing mapping multiplexing mode, increasing ODU1 mapping to ODU2 and ODU3 1.25G tributary timing, and increasing ODU2 mapping to ODU3 1.25G. Branch timing; other new rates (ODU0, ODU2e, ODUflex) mapped to ODU1, ODU2, ODU3, ODU4 are all 1.25G tributary timing mapping multiplexing. According to G.sup 43, ODU2e can be mapped to ODU3el's 2.5G tributary timing, and ODU2e can also be mapped to ODU3el's 1.25G tributary timing. Most low-order ODUs have the same number of branch timings in the higher order; however, in ODU2e, ODU2e needs to occupy 9 1.25G branch timings or 5 2.5G branch timings in ODU3, while ODU2e is in ODU4. It takes 8 1.25G branch timings. Figure 3 shows the detailed mapping multiplexing path structure of the G.709 standard and the G.sup43 standard.

The idea of a flexible ODU was initially discussed extensively in the September 2008 ITU-T Q11/SG15 Intermediate Conference and the December 2008 ITU-T SG15 Plenary. The original idea of Flexible ODU was to provide OTN bit transparent transmission for client signals at any bit rate. ODUflex is currently expected to support new bit rates that are not efficiently mapped to ODU2, ODU3 or ODU4. ODUflex is treated as a low-order ODU; an ODUflex occupies the number of tributary sequences of any integer multiple of the high-order ODUk. The ODUflex bandwidth can be dynamically adjusted.

The recommended packet ODUflex size is: nxl.24416 Gbit/s+20ppm (1 < n < 80), while the CBR ODUflex size is 239/238 times the client signal rate. The newly defined ODUflex no longer provides mapping for client signals that have been mapped to ODU0, ODU1, ODU2, and ODU3. For CBR client signals, the customer signal is preferably mapped to ODUflex via BMP. The ODUflex rate is 239/238 times the client signal rate (customer signal rate is 2.5G or more). For packet service client signals, it is currently discussed to use GFP to map customer signals to ODUflex; ODUflex = n*1.24416G, where 1 n 80; The ODUflex bit rate is an integer multiple of the number of branch timings of the high order ODUk.

After the release of the G.709 standard in 2003, after several years of development, OTN equipment was deployed in a large number, and the latest G.709 standard has undergone four major changes. After the newly deployed OTN equipment is loaded into the control plane, An end-to-end label switched path may control many old and new devices at the same time. The old device can only support 2.5G tributary timing units, while the new device can support both 2.5G tributary timing units and 1.25G tributary timing units. When an end-to-end label switching path passes through old devices and new devices, the interconnection and interoperability involved in managing end-to-end services becomes a real technical problem.

As shown in Figure 4, the OTN network has been deployed on the network. All node devices in the OTN network are based on the G.709 standard version released in 2003. Each node in the network does not support ODU0 and ODUflex, and is based on 2.5G. Road timing. With the large number of applications of data services, operators need to introduce ODU0 and ODUflex applications into existing networks. When ODU0 and ODUflex applications are introduced into existing networks, there are networks that support 1.25G TS and 2.5G TS networks that have been deployed. The problem, if no other technology is introduced, the operator has to upgrade all the nodes in the existing network to support ODU0 and ODUflex, which will inevitably destroy the OTN network that the operator has invested.

In addition, an end-to-end ODUk service may pass through many old and new devices at the same time. The old device can only support 2.5G tributary timing units, while the new device can support both 2.5G tributary timing units and 1.25G tributary timing. Unit; when an end-to-end ODUk passes through the old equipment and the new equipment, the interconnection and interoperability involved in managing the end-to-end service becomes a practical technical problem. At the same time, there is also the problem of introducing ODU0 and ODUflex services into the OTN network and interworking with the deployed networks.

Summary of the invention

The technical problem to be solved by the present invention is to provide a G.709-based multiplexing route calculation method and a path calculation device in an optical switching network automatic switching optical network.

In order to solve the above problem, the present invention provides a G.709-based multiplexed route calculation method, which is applied to an optical transport network including a gateway network element, and includes: The path calculation unit acquires multi-level multiplexing capability supported by the gateway network element;

When the path calculation unit receives the end-to-end path calculation request of the path calculation client, the end-to-end route is calculated according to the acquired multi-level multiplexing capability supported by the gateway network element, and the gateway network element through which the end-to-end route passes is determined. And selecting multi-level multiplexing capability for the gateway network element that passes through.

The foregoing method may further have the following feature: when the path calculation unit receives the end-to-end path calculation request of the path calculation client, calculate an end-to-end route according to the acquired multi-level multiplexing capability supported by the gateway network element, and determine After the step of the end-to-end routing of the gateway network element and the step of selecting the multi-stage multiplexing capability for the gateway network element, the method further includes:

When the path calculation client is a node in the network managed by the path calculation unit, the path calculation unit routes the end-to-end route, the gateway network element through which the end-to-end route passes, and the gateway network that passes through The multi-stage multiplexing capability of the meta-selection is returned to the path computation client.

When the path calculation client is another path calculation unit, the path calculation unit saves the end-to-end route, the gateway network element through which the end-to-end route passes, and the multi-level complex selected for the passed gateway network element. Use the capability and return a routing key to the path to calculate the client.

The foregoing method may further have the following feature, in the step that the path calculation unit acquires the multi-stage multiplexing capability supported by the gateway network element,

The path calculation unit acquires multi-stage multiplexing capability supported by the gateway network element by using a routing protocol or a configuration of the receiving management plane to the path calculation unit.

The foregoing method may further have the following feature: the end-to-end path calculation request specifies a multi-stage multiplexing capability that is used or cannot be used by all gateway network elements through which the end-to-end route passes;

Calculating the end-to-end route according to the acquired multi-level multiplexing capability supported by the gateway network element, and determining the gateway network element through which the end-to-end route passes and the multi-stage multiplexing capability selected for the passed gateway network element In the step,

The path calculation unit calculates the end-to-end path specified in the request according to the end-to-end path The multi-stage multiplexing capability of the gateway network element on the end-to-end route is selected by the multi-stage multiplexing capability of the gateway network element that is used or not, and the multi-level multiplexing capability supported by the gateway network element.

The foregoing method may further have the following feature: the end-to-end path calculation request explicitly specifies a gateway network element to be passed by the end-to-end route, and selects a multi-level complex to be used or cannot be used for the gateway network element to pass through. Ability

The path calculation unit calculates, according to the end-to-end path, the gateway network element to be passed in the request, the multi-stage multiplexing capability to be used or not used, and the gateway network element support selected for the gateway network element to be passed. The multi-stage multiplexing capability calculates the end-to-end route and selects multi-stage multiplexing capability for the gateway network element through which the end-to-end routing passes.

The foregoing method may further have the following feature: the end-to-end path calculation request specifies a gateway network element to be passed by the end-to-end route, and selects a multi-stage multiplexing capability to be used or cannot be used for a gateway network element to pass through. The steps include:

Inserting, in the end-to-end path calculation request, the routing object IRO includes a gateway network element to which the end-to-end route passes, inserting an attribute object in each sub-object of the gateway network element to pass through, The attribute object includes a type field, a length field, a flag field, and a multi-level multiplexing capability information field, where:

a type field indicating the type of the attribute object;

a length field, configured to indicate a length of the flag field and the multi-level multiplexing capability information field; a flag field, configured to indicate that the subsequent multi-level multiplexing capability must be selected or cannot be selected; the multi-level multiplexing capability information field, used for Carrying a multi-stage multiplexing capability to be used selected by the gateway network element, the multi-stage multiplexing capability information field includes M sub-fields, each sub-field indicating a multi-stage multiplexing capability, and each sub-field includes multi-stage multiplexing The layer number information field and the multi-stage multiplexed signal type information field, M is the number of multi-stage multiplexing capabilities specified.

The present invention further provides a path calculation apparatus, the path calculation apparatus is configured to acquire a multi-stage multiplexing capability supported by a gateway network element; and when the receiving path calculates a client end-to-end path calculation request, the root The end-to-end routing is calculated according to the acquired multi-level multiplexing capability supported by the gateway network element, and the gateway network element through which the end-to-end routing passes is determined and the multi-stage multiplexing capability is selected for the passed gateway network element.

The path calculation device may further have the following feature, the path calculation device is further configured to: when the path calculation client is a node in a network managed by the path calculation device, routing the end-to-end, the end The gateway network element through which the inbound route passes and the multi-stage multiplexing capability selected for the passed gateway network element are returned to the path calculation client.

The path calculation device may further have the following feature, the path calculation device is further configured to: when the path calculation client is another path calculation device, save the end-to-end route, the gateway through which the end-to-end route passes The network element and the multi-stage multiplexing capability selected for the passed gateway network element, and returning a routing key to the path computing client.

The path calculation device may further have the following feature: the path calculation device is configured to: acquire the multi-level multiplexing capability supported by the gateway network element by using a routing protocol or a configuration of the path management device by the receiving management plane.

The path calculation device may further have the following feature: the path calculation device is configured to: when the end-to-end path calculation request specifies that all the gateway network elements through which the end-to-end route passes or cannot be used, the multi-level complex When the capability is used, the multi-stage multiplexing capability used by the gateway network element that the end-to-end route specified in the request is used or cannot be used according to the end-to-end path and the multi-stage multiplexing supported by the gateway network element are calculated according to the end-to-end path Capability, selecting multi-level multiplexing capability for the gateway network element on the end-to-end route.

The path calculation device may further have the following feature: the path calculation device is configured to: explicitly specify, in the end-to-end path calculation request, a gateway network element to pass through the end-to-end route and a gateway to pass through When the network element selects the multi-stage multiplexing capability to be used or cannot be used, the gateway network element to be passed in the request is calculated according to the end-to-end path, and the selected and selected network element to be passed is used or cannot be used. The multi-stage multiplexing capability and the multi-level multiplexing capability supported by the gateway network element calculate the end-to-end route, and select multi-stage multiplexing capability for the gateway network element through which the end-to-end routing passes.

The G.709-based multiplexing route calculation method and the path calculation device provided by the invention implement the calculation of the back-to-end route of the gateway network element. BRIEF abstract

Figure 1 is a mapping multiplexing structure of the G.709 standard published in 2003;

Figure 2 shows the mapping multiplexing structure of the G.709 Amendment3 and G.sup 43 standards; Figure 3 is the detailed mapping multiplexing structure of the G.709 standard and the G.sup43 standard;

Figure 4 shows the OTN network that the operator has invested in. The implementation of each node in the network is based on the G.709 standard released in 2003. Each node in the network does not support ODU0 and ODUflex, and is based on 2.5G. Road timing

FIG. 5 is a network structure in which a gateway network element is supported to support multi-level multiplexing when an OTN device supporting ODU0 and ODU _flex signals is added to the existing network shown in FIG. 4. Since the gateway network element is introduced, it is not necessary to update each node in the existing network;

Figure 6 is an OTN network structure diagram of the tunnel network design, introducing a Gateway (Network) element, and multiplexing ODU0 and ODUflex to ODU2 or ODU3 first to minimize the number of cross-connections that need to be created in the intermediate node;

7 is a network structure in which a gateway network element is supported to support multi-level multiplexing when an OTN device supporting ODU0 and ODUflex signals is added to the existing network shown in FIG. 4; each gateway network element supports Multi-level multiplexing capability is different;

8 is a path calculation device (PCE) in the network described in FIG. 7, which is responsible for path calculation of three networks of ODU 2 network (Network) 1, ODU2 Network 3, and ODU3 Network 2, and the PCE can see three All topological information of the network;

9 is an extension of the network path calculation function described in FIG. 8. When the path calculation client (PCC) requests the PCE to perform path calculation, the path calculation may further constrain the path to calculate the specified multi-stage multiplexing capability used by the specified gateway network element;

10 is an extension of the network path calculation function described in FIG. 8. When the PCC requests the PCE to perform path calculation, the PCC can further constrain the path to calculate the specified multi-level multiplexing capability that is not used by the specified gateway network element;

FIG. 11 is an extension of the network path calculation function described in FIG. 9, and the end-to-end ODUk service path calculation is performed by two mutually compatible PCEs, and the PCE 1 is responsible for the two networks of the ODU2 Network 1 and the ODU2 Network 3. Path calculation, while PCE 2 is responsible for ODU3 Path calculation of the Network 2 network;

FIG. 12 is an extension of the network path calculation function described in FIG. 9, and the end-to-end ODUk service path calculation is performed by two non-communicable PCEs, and the PCE 1 is responsible for the two networks of the ODU2 Network 1 and the ODU2 Network 3. Path calculation, and PCE 2 is responsible for the path calculation of the ODU3 Network 2 network;

13 is a schematic diagram of an extension of an IRO object in the PCRep protocol of the present invention; FIG. 14 is a TLV encoding in a specific embodiment of FIG.

Figure 15 is a TLV code in one embodiment of Figure 13. Preferred embodiment of the invention

The invention will now be further described with reference to the drawings and specific embodiments.

The OTN standard has always supported single-level ODU multiplexing. The subsequent result in OTN vl is that ODU1 maps directly to a branch timing of ODU3 without first mapping to ODU2. The motivation for this architecture is to reduce complexity. During the normal evolution of the architecture, the newly added OTN function is expected to be at a higher rate, so the single-stage multiplexing concept will be pushed forward more easily. That is, if the rates are all increasing, single-stage multiplexing can easily continue to be used in the OTN architecture. Introducing ODU0 and ODU _flex into the OTN hierarchy makes the newly added ODUk signal rate much lower than the existing rate, which brings some different challenges, because the newly added rate can be the customer of the existing rate. Therefore, there is a clear application, and two-stage multiplexing is expected to assist in introducing ODU0 and ODU _flex signals into existing networks, thereby eliminating the need to update each node in the existing network. Using two-level multiplexing in one domain allows operators to apply new rate limiting to only those nodes that need to support these new rates.

An OTN network may be a client layer of another OTN network. For example, Carrier A may have an OTN network consisting of low-order ODUi and high-order ODUj (i<j), and high-order ODUj in Carrier A is carried by OTUj. To operator B; operator B regards ODUj as a low-order ODUj to a higher-order ODUk (j<k). There are two levels of ODUs in Carrier A or Carrier B; however, the higher-order ODUj in Carrier A becomes lower-order in Carrier B.

Two-stage multiplexing is expected to assist in introducing ODU0 and ODUflex signals into existing networks. Therefore, it is not necessary to update each node in the existing network, but a gateway (network) network element needs to be introduced to support multi-level multiplexing.

Some NEs are upgraded to gateway NEs. Multi-stage multiplexing is implemented on these gateway NEs to introduce ODU0 and ODU _flex applications into the deployed network and complete 1.25G TS signals and 2.5. The conversion between the G TS signals solves the interconnection between the 1.25G TS network and the already deployed 2.5G TS network. The method not only protects the existing OTN network of the operator, but also introduces the new ODUk application into the existing OTN network.

As shown in FIG. 5, the network shown in FIG. 4 is upgraded to obtain the network shown in FIG. 5. The gateway network element in FIG. 5 supports two-level multiplexing, thereby allowing ODU0 to be supported in the deployed network. ODU0 maps to ODU1 or ODU2 first, and then ODU1/ODU2 maps to ODU3. Nodes 4, 5, and 6, do not need to see ODU0, but directly exchange ODU1 or ODU2, thus protecting the existing network of the operator. Introduce new applications and services, and add value-added services to operators' existing networks.

In addition to the network upgrade scenario, the second potential multi-level reuse application is a tunnel-based network design. In an ODU4 network, each ODU4 has 80 branch timings. Assume that a large number of ODU0 and ODU _flex require 3-4 branch timings. If a large number of circuit services share the same termination point (or even part of the entire path), from a management perspective, a gateway network element (Gateway) is introduced, and ODU0 and ODU _{flex are} first multiplexed to ODU2 or ODU3 to minimize the need. The number of cross-connections created at the intermediate node. ODU2/ODU3 effectively creates a tunnel through the ODU4 network used by ODU0/ODU _flex . As shown in Figure 6, the ODU0/ODU _{flex is} only visible to the gateway NE. Although multi-stage multiplexing increases the complexity of the gateway network element, it reduces the number of cross-connections that need to be configured at other non-gateway network element nodes.

The management plane and the control plane obtain the detailed information of each link in the OTN network by using the prior art, and the information includes the tributary timing granularity supported by the link and the maximum number of supported tributary sequences (that is, the maximum of the link). Bandwidth), the number of tributary sequences available for the current link, and the low-order signal types that the link can support. For Figure 7, the link between Gateway 1 and 4 nodes and Gateway 3 and 7 nodes, because ODU0 can be mapped to the ODU3 Network 2 network through two-stage multiplexing (that is, ODU0 can be mapped to ODU1 or ODU2, and then Map ODU1 or ODU2 to ODU3), so if you only know the low-order signals supported by these links, it is not enough. To calculate the route for the path computation entity, you also need to know how the ODU0 is mapped to the ODU 3 Network 2 network, that is, the multi-level multiplexing capability supported by the links between the Gateway 1 and 4 nodes and the Gateway 3 and 7 nodes must be The path calculation entity knows. Therefore, before the management plane or the control plane calculates an end-to-end ODUk service, it must obtain the multi-level multiplexing capability constraint information of the gateway network element in the network. The path computation entity in the control plane can obtain the multi-level multiplexing capability of the network element by extending an automatic discovery protocol or a routing protocol.

After determining which gateway network elements the end-to-end route passes through, it is determined which gateway network elements are associated with each other. Therefore, two gateway network elements for creating a tunnel can be explicitly specified in the signaling message; further, Create a higher rate ODUj (such as ODU2) connection (i<j) than the end-to-end ODUi (such as ODU0) to be established between the two associated pairs of gateway network elements.

Therefore, the present invention provides a route calculation method and apparatus for the end-to-end ODUk service when the gateway network element is introduced into the existing OTN network, so as to be able to determine the gateway network element that passes through the end-to-end ODUk service, and the gateway network element. Select the appropriate multi-level multiplexing capability.

The invention introduces a PCE (Path Computation Element) to assist in the calculation of ODUk end-to-end service routing. The PCE obtains the gateway network element through a routing protocol (OSPF-based Open Shortest Path First Protocol (OSPF-TE) or Traffic Engineering-based Intermediate System to Intermediate System (IS-IS-TE)) or management plane configuration. The multi-level multiplexing capability constraint information supported by the obtained multi-level multiplexing capability constraint information of the obtained gateway network element is used for end-to-end routing calculation.

The path computation entity also needs to determine the gateway network elements through which the end-to-end routing passes, and select corresponding multi-stage multiplexing capabilities on the gateway network elements. In the route calculation process, when the end-to-end ODUk service passes through multiple gateway network elements, the path calculation entity must select the corresponding multi-stage multiplexing and demultiplexing capability for the end-to-end ODUk service on these gateway network elements.

After the route calculation is completed, the PCE sends the end-to-end routing information to the PCC (Path Computation Client) through the path calculation response (PCRep) message. In the returned end-to-end routing information, the PCE is carried. The multi-stage multiplexing capability selected by the gateway network element through which end-to-end routing passes.

When the PCC requests the PCE to calculate an end-to-end route, it can explicitly specify the end-to-end route to be The gateway network element passes, and specifies the multi-stage multiplexing capability used or not used on the gateway network element to be passed. When calculating the end-to-end routing, the PCE needs to use the obtained multi-level multiplexing capability information of the gateway network element for end-to-end routing calculation, and also needs to explicitly specify the passing gateway network element by the PCC, and specify the The constraint information such as the multi-stage multiplexing capability used or not used on the gateway network element to be passed is used for end-to-end route calculation.

The PCC can also specify only the multi-level multiplexing capability used on the entire end-to-end routed gateway network element or cannot use some kind of multi-stage multiplexing capability. It is not necessary to select or use a specific multi-level for a specific gateway network element. Reuse capability. When calculating the end-to-end routing, the PCE needs to use the obtained multi-level multiplexing capability information of the gateway network element for the end-to-end routing calculation, and also needs to pass all the gateway network elements that the end-to-end routing passes, according to the PCC. Explicitly specify multi-level multiplexing capabilities that are or cannot be used, and select specific multi-level multiplexing capabilities.

The present invention provides a G.709-based multi-stage multiplexed route calculation method, which is applied to an optical transport network including a gateway network element, and includes:

The path calculation unit acquires multi-level multiplexing capability supported by the gateway network element;

When the path calculation unit receives the end-to-end path calculation request of the path calculation client, the end-to-end route is calculated according to the acquired multi-level multiplexing capability supported by the gateway network element, and the gateway network through which the end-to-end route passes is determined. The multi-stage multiplexing capability selected on the gateway and the gateway network element that it passes through.

When the path calculation client is a node in the network managed by the path calculation unit, the path calculation unit routes the end-to-end route, the gateway network element through which the end-to-end route passes, and the gateway that passes through The multi-stage multiplexing capability selected on the network element is returned to the path computing client.

When the path calculation client is another path calculation unit, the path calculation unit saves the end-to-end route, the gateway network element through which the end-to-end route passes, and the selected gateway network element. The level multiplexing capability returns a routing key to the path computation client.

The path calculation unit obtains the multi-stage multiplexing capability supported by the gateway network element by using a routing protocol or a configuration of the path management unit of the receiving management plane.

The end-to-end path calculation request specifies a multi-stage multiplexing capability that all gateway network elements on the end-to-end route use or cannot use; the path calculation unit specifies the end-to-end path request Multi-level complex of all gateway network elements used or not available on the end-to-end route Selecting a specific multi-stage multiplexing capability for the gateway network element on the end-to-end route by using the capability and the multi-stage multiplexing capability supported by the gateway network element.

Wherein: the end-to-end path calculation request explicitly specifies a multi-level multiplexing capability to be used or not available on the gateway network element through which the end-to-end route passes and the gateway network element to be passed; The unit calculates, according to the end-to-end path, the gateway network element to be passed in the request and the multi-stage multiplexing capability to be used or not available on the gateway network element to be passed, and the multi-stage multiplexing supported on the gateway network element. The capability calculates the end-to-end route and selects a particular multi-stage multiplexing capability for the gateway network element on the end-to-end route.

The end-to-end path request specifies, in the following manner, a multi-stage multiplexing capability to be used or not available on the gateway network element through which the end-to-end route passes and the gateway network element to be passed through: The gateway network element including the end-to-end route included in the route-containing object (IRO) carried in the end-path request, inserts a hop (HOP) attribute in each sub-object of the gateway network element to pass through (ATTRIBUTE) Object, the HOP ATTRIBUTE object includes a type field, a length field, and a multi-level multiplexing capability information field, where:

a type field indicating the type of the HOP-ATTRIBUTE object;

a length field, used to indicate a length of the multi-level multiplexing capability information field;

a flag field, configured to indicate that the subsequent multi-stage multiplexing capability must be selected or cannot be selected; the multi-level multiplexing capability information field, configured to carry the multi-stage multiplexing capability to be used on the gateway network element, including M subfields, Each subfield indicates a multi-stage multiplexing capability, and each subfield includes a multi-level multiplexing layer information field and a multi-level multiplexing signal type information field, where M is the number of multi-stage multiplexing capabilities specified.

As shown in Figure 7, after the Gateway network element is introduced to the existing network and the OTN device node implemented according to the latest version of the G.709 standard is deployed, two 10G OTN networks and one 40G OTN network and 10G OTN network are formed. The tributary timing size supported by each link on the top is 1.25G TS. Two 10G OTN networks are interconnected through Gateway 1 and Gateway 3 and 40G OTN networks, and the link between them is an OTU3 link. The switching capability supported by each node in the two 10G OTN networks is different. The nodes 1, 2, 3, and Gateway 1 in the ODU 2 Network 1 only support the switching capabilities of ODU0, ODU1, and ODUflex. ODU2 Network Nodes 8, 9, 10, and Gateway 3 in 3 only support the switching capability of ODU0 and ODUflex, because the operator only wants ODU2 Network 3 to be responsible for accessing 1 GigE (ODu0) and 10 GigE (ODU2/ODU2e) services, so It is more economical to only make ODU0/ODU2 exchanges, and there is no need to exchange ODU1. The multi-level multiplexing capabilities supported by the gateway NE are as follows:

Multi-level multiplexing capability supported by the Gateway 1 network element:

ODU0-ODU1-ODU3

ODU0-ODU2-ODU3

ODU1-ODU2-ODU3

ODUflex-ODU2-ODU3

Multi-level multiplexing capabilities supported by the Gateway 3 network element:

ODU0-ODU2-ODU3

ODUflex-ODU2-ODU3

At the same time, both Gateway 1 and Gateway 3 support the following single-stage multiplexing capabilities:

ODU1-ODU3

ODU2-ODU3

Before the control plane establishes an end-to-end GigE (ODU) through distributed signaling, the path calculation unit uses the obtained multi-level multiplexing capability constraint information of the gateway network element for the end-to-end ODUk service path calculation, and in the route calculation process When the end-to-end ODUk service passes through multiple gateway network elements, the path calculation entity selects corresponding multi-stage multiplexing and demultiplexing capabilities for the end-to-end ODUk services on the gateway network elements.

Example 1

As shown in Figure 8, the PCE can see all the topology information of ODU2 Network 1, ODU3 Network 2 and ODU2 Network 3. The PCE uses the routing protocol (OSPF-TE or IS-IS-TE) or the management plane to configure the PCE to obtain the multi-stage multiplexing capability supported by the gateway NEs 1 and Gateway 3.

The route calculation method provided in this embodiment includes:

Step 101: The PCC (in this embodiment, the node 1) sends an end-to-end route calculation request to the PCE. The PCE is requested to calculate an ODU0 end-to-end service between node 1 and node 10. Step 102: After receiving the end-to-end route calculation request, the PCE uses the obtained multi-level multiplexing capability information of the gateway network element for end-to-end route calculation.

The PCE uses the prior art to calculate an available end-to-end route, such as the passing nodes 1, 3, Gateway 1, 4, 6, 7, Gateway 3, 9, 10. Since Gateway 3 supports only two-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 for ODU0 services, Gateway 1 supports the multiplexing and demultiplexing capabilities of ODU0-ODU1-ODU3 and ODU0-ODU2-ODU3. PCE can only The end-to-end ODU0 service selects the multi-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 on Gateway 1 and Gateway 3. Otherwise, the signal cannot be transmitted end-to-end and passes through ODU3 Network 2.

Step 103: After the PCE route is calculated, the end-to-end routing information is returned to the PCC through the PCRep message (in this embodiment, the node 1). In the returned end-to-end routing information, the PCE is carried to the end. The multi-stage multiplexing capability selected by the gateway network element through which the end routing passes.

As shown in Figure 8, the end-to-end routing information is encapsulated into ERO objects, including 1, 3, Gateway 1, 4, 6, 7, Gateway 3, 9, 10 and other sub-objects, which are in Gateway 1 and Gateway 3 In the sub-object, the multi-level multiplexing capability selected on the corresponding gateway network element is identified, including:

Gateway 1 selected: ODU0-ODU2-ODU3;

Gateway 3 selected: ODU0-ODU2-ODU3.

The specific encapsulation method is shown in Figure 8. The hop (HOP) _ attribute (ATRIBUTE) subtype length value (Sub-TLV) in the ERO (Include Route Object) sub-object can be carried on the corresponding gateway network element. The selected multi-stage multiplexing capability, through the ERBO (Explicit Region Boundary Object), carries the gateway network elements (Gateway 1 and Gateway 3) through which the end-to-end route determined by the PCE passes. The encoding format of the specific encapsulation method is referred to in Embodiment 6.

Example 2

As shown in FIG. 9, the PCE can see all the topology information of ODU2 Network 1, ODU3 Network 2, and ODU2 Network 3. The PCE uses the routing protocol (OSPF-TE or IS-IS-TE) or the management plane to configure the PCE to obtain the multi-level multiplexing capability information supported by the gateway network element. The route calculation method in this embodiment includes:

Step 201: The PCC (Node 1) requests the PCE to calculate an ODU0 end-to-end service between the 1st and 10th nodes. At the same time, the IRO (Include Route Object) in the PCReq message is specified to pass through Gateway 1 and Gateway 3, and a HOP_ATTRIBUTE is inserted in the Gateway 1 and Gateway 3 sub-objects respectively, for the two gateway network elements. The designation uses multi-level multiplexing capabilities: ODU0-ODU2-ODU3. Of course, different multi-level multiplexing capabilities can also be specified for different gateway network elements. Refer to Example 6 for details.

Step 202: The PCE uses the obtained multi-level multiplexing capability constraint information of the gateway network element and the gateway network element specified by the PCC and the multi-stage multiplexing capability (method) specified thereon for the end-to-end ODUk service path calculation. .

The PCE uses the prior art to calculate an available end-to-end route, such as the passing nodes 1, 3, Gateway 1, 4, 6, 7, Gateway 3, 9, 10. Since the PCC has selected the same multi-stage multiplexing capability (method) for the two gateway network elements: ODU0-ODU2-ODU3, the PCE needs to verify whether the multi-stage multiplexing capability specified by the PCC meets the transmission requirements of the service. .

Since Gateway 3 supports only two-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 for ODU0 services, Gateway 1 supports the multiplexing and demultiplexing capabilities of ODU0-ODU1-ODU3 and ODU0-ODU2-ODU3, so PCE must be the end. The ODU0 service at the end selects the multi-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 on Gateway 1 and Gateway 3. At this time, the multi-stage multiplexing capability specified by the PCC passes the PCE check.

Step 203: After the PCE route is calculated, the end-to-end routing information is returned to the PCC through the PCRep message, that is, the node 1; in the returned end-to-end routing information, the PCE is the gateway through which the end-to-end routing passes. The multi-level multiplexing capability selected by the network element.

As shown in Figure 9, the end-to-end routing information is encapsulated into ERO objects, including 1, 3, Gateway 1, 4, 6, 7, Gateway 3, 9, 10 and other sub-objects, which are in Gateway 1 and Gateway 3 The HOP-ATTRIBUTE in the sub-object identifies the multi-level multiplexing capability (method) selected on the corresponding gateway network element, that is:

Gateway 1 selected: ODU0-ODU2-ODU3;

Gateway 3 selected: ODU0-ODU2-ODU3. Example 3

As shown in Figure 10, the PCE can see all the topology information of ODU2 Network 1, ODU3 Network 2 and ODU2 Network 3. The PCE uses the routing protocol (OSPF-TE or IS-IS-TE) or the management plane to configure the PCE to obtain the multi-level multiplexing capability information supported by the gateway NE.

The route calculation method in this embodiment includes:

Step 301: The PCC (Node 1) requests the PCE to calculate an ODU0 end-to-end service between the 1st and 10th nodes. At the same time, the IRO (Include Route Object) in the PCReq message is specified to pass through Gateway 1 and Gateway 3, and in the Gateway 1 and Gateway 3 sub-objects, each HOP-ATTRIBUTE is inserted, for the two gateway networks. The meta-specified cannot use multi-level multiplexing capability: ODU0-ODU2-ODU3.

Step 302: The PCE obtains the multi-level multiplexing capability constraint information of the obtained gateway network element and the gateway network element specified by the PCC and the multi-stage multiplexing capability (method) specified thereon for the end-to-end ODUk service path calculation. .

The PCE uses the prior art to calculate an available end-to-end route, such as the passing nodes 1, 3, Gateway 1, 4, 6, 7, Gateway 3, 9, 10. Gateway 3 supports only two-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 for ODU0 services, although Gateway 1 supports the multiplexing and demultiplexing capabilities of ODU0-ODU1-ODU3 and ODU0-ODU2-ODU3, since PCC has already The two gateway NEs cannot specify the ODU0-ODU2-ODU3 multi-stage multiplexing capability (method). Therefore, the PCE cannot select multi-stage multiplexing and demultiplexing capabilities on the Gateway 1 and Gateway 3 for the end-to-end ODU0 service. The PCE end-to-end path calculation failed.

Step 303: After the PCE route calculation fails, the failure information is returned to the PCC through the PCRep message, which includes the error information that cannot be selected to the appropriate multi-stage multiplexing capability (method) on the Gateway 3.

Example 4

The ODUk end-to-end route calculation can be performed through multiple PCEs. This scenario can be used for path computation interconnection between different operators or path computation interconnection between different routing domains (different vendors) in the same carrier. The PCE 1 in Figure 11 is responsible for the path calculation of the two 10G networks ODU2 Network 1 and ODU2 Network 3. PCE 2 is responsible for the path calculation of the ODG3 Network 2 of the 40G network. PCE 1 and PCE 2 can communicate directly and perform end-to-end path calculation by cooperating with each other. Since PCE 1 can only see the routing information of the network ODU2 Network 1 and ODU2 Network 3 and the Gateway 1 and Gateway 3 nodes, PCE 2 can only see the routing information of the network ODU3 Network 2 and the Gateway 1 and Gateway 3 nodes.

PCE1 and PCE 2 obtain the multi-level multiplexing capability information supported by the gateway NE through the routing protocol (OSPF-TE or IS-IS-TE) or the configuration of the management plane.

The route calculation method in this embodiment includes:

Step 401: The PCC (Node 1) requests the PCE 1 to calculate an ODU0 end-to-end service between the node 1 and the node 10, and specifies the end-to-end services Gateway 1 and Gateway 3, and the two gateway networks. The meta-designation uses multi-level multiplexing capabilities: ODU0-ODU2-ODU3. Of course, different multi-level multiplexing capabilities can also be specified for different gateway network elements. For details, refer to Embodiment 6. Of course, you can also not specify. Also, according to the method of Embodiment 3, the PCC can also specify that certain multi-stage multiplexing capabilities (methods) cannot be used on some gateway network elements.

Step 402: Using the prior art, the PCE 1 can determine that the Gateway 1 and the Gateway 3 pass through the end-to-end ODU0 service, but the PCE 1 cannot view the topology information of the ODU3 Network 2 network, and cannot calculate the Gateway 1 and the Gateway 3 The routing information in the ODU3 Network 2, and then the PCE 1 requests the PCE 2 to calculate the route between the Gateway 1 and the Gateway 3 in the ODU3 Network 2. PCE 1 is a PCC of PCE2. In the PCReq message, it is specified to pass through Gateway 1 and Gateway 3, and the multi-level multiplexing capability is used for both gateway NEs: ODU0-ODU2-ODU3. Similarly, according to the method of Embodiment 3, PCE 1 as a PCC can also specify that certain multi-stage multiplexing capabilities (methods) cannot be used on some gateway network elements.

Step 403: The PCE 2 calculates a route between the Gateway 1 and the Gateway 3 by using the prior art in the ODU3 Network 2 network: Gateway 1, 4, 6, 7, and Gateway 3. Since PCE 1 has selected the same multi-stage multiplexing capability for the two gateway network elements: ODU0-ODU2-ODU3, PCE 2 needs to verify whether the multi-level multiplexing capability specified by PCE 1 meets the transmission requirements of the service. .

Since Gateway 3 supports only two-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 for ODU0 services, Gateway 1 supports the multiplexing and demultiplexing capabilities of ODU0-ODU1-ODU3 and ODU0-ODU2-ODU3, so PCE 2 must be End-to-end ODU0 services in Gatewayl and The multi-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 are selected on Gateway3, so that the multi-stage multiplexing capability specified by PCE 1 passes the verification of PCE 2.

Step 404: After the PCE 2 route is calculated, since the PCE 2 cannot expose the routing information in the ODU3 Network2 network to the PCE 1, the PCE 2 uses the existing technology to use the route information: 4, 6, and 7 using the Path-Key. Technical alternatives. That is, PCE2 generates a keyword for the routing information (4, 6, 7) in the calculated network range, and names it as a routing key (Path-Key), and saves the Path-Key in PCE2 - a specific value and Corresponding relationship between the calculated routes, the routing information returned by PCE2 to PCE1 uses a specific value of Path-Key instead of the calculated routing information 4, 6, 7 . The routing information returned by PCE1 to the PCC includes the Path. -Key, the Path-Key is included in the signaling of the connection signaling establishment process. When the signaling arrives at Gateway 1, Gateway 1 requests the PCE2 to return the detailed routing information in the ODU3 Network 2 network through the Path-Key.

If PCE 2 is the routing information calculated between the Gateway 1 and the Gateway 3 in the ODU3 Network 2 network, some other gateway network elements are also included, and multi-level multiplexing capability is selected for the gateway network elements, and the routing information is also It also needs to be saved to PCE2. In addition to the routing information required by the existing technology, the multi-level multiplexing capability information on the gateway network element is saved to PCE2 along with the ERO.

Thus, PCE 2 returns the routing information Gateway 1, Path-Key and Gateway 3 to PCE 1 via the PCRep message. The returned end-to-end routing information carries the multi-level multiplexing capability selected by the PCE for the gateway network element through which the end-to-end routing passes. If the network managed by the PCE2 further includes some gateway network elements, for example, the PCE2 internal There is also a pair of gateway network elements Gateway 4 and Gateway 5, which cannot return the multi-level multiplexing capability information selected on the internal gateway network element to PCE1. This information is saved to PCE2 along with the routing information calculated by PCE2.

As shown in Figure 11, the routing information between Gateway1 and Gateway 3 is encapsulated into an ERO object, including child objects such as Gateway 1, Path-Key, and Gateway 3. In the sub-objects of Gateway 1 and Gateway 3, the identifier corresponds to The multi-level multiplexing capability selected on the gateway network element is:

Gateway 1 selected: ODU0-ODU2-ODU3;

Gateway 3 selected: ODuO-ODU2-ODU3. Specifically, the HOP-ATRIBUTES Sub-TLV in the ERO object carries the multi-stage multiplexing capability selected by the corresponding gateway network element.

Step 405: After calculating the route of the ODU2 Network 1 and the ODU2 Network 3 network, the PCE 1 is connected with the calculation result of the PCE2 to form an end-to-end route, that is, 1, 3, Gateway 1, Path-Key, and Gateway 3. 9, 10, 10. PCE 1 will return the end-to-end routing information to the PCC through the PCRep message, which is node 1.

Example 5

As shown in Figure 11, PCE 1 can see all the topology information of ODU2 Network 1, and ODU2 Network 3. PCE 2 can see the topology information of ODU3 Network 2 network. PCE 1 is responsible for path calculation of ODU2 Network 1 and ODU2 Network 3 of two 10G networks, and PCE 2 is responsible for path calculation of ODU3 Network 2 of 40G network. There is no direct communication between PCE 1 and PCE 2. When PCE 1 calculates an end-to-end ODUk service, such as an ODU0 service between 1 and 10 nodes, PCE 1 can determine that Gateway 1 and Gateway 3 pass through the existing technology for the end-to-end ODU0 service, but due to PCE 1 The topology information of the ODU3 Network 2 network cannot be seen. The routing information between the Gateway 1 and the Gateway 3 in the ODU3 Network 2 cannot be calculated, and the two PCEs cannot communicate. Therefore, the signaling can only wait until the Gateway 1 arrives at the Gateway 1. Gateway 1 requests PCE 2 to calculate the route between Gateway 1 and Gateway 3 in ODU3 Network 2, and PCE 2 determines the multi-stage multiplexing capability selected on Gateway 1 and Gateway 3, and in the PCRep response message, Gateway 1 returns the selected multi-stage multiplexing capability.

PCE 1 and PCE2 obtain the multi-level multiplexing capability information supported by the gateway NE through the routing protocol (OSPF-TE or IS-IS-TE) or the configuration of the management plane.

The route calculation method in this embodiment includes:

Step 501: The PCC (Node 1) requests the PCE 1 to calculate an ODU0 end-to-end service between the 1 and 10 nodes, and specify to pass through Gateway 1 and Gateway 3, and specify multiple levels for both gateway NEs. Reuse capability: ODU0-ODU2-ODU3. Of course, different multi-level multiplexing capabilities can also be specified for different gateway network elements. For details, refer to Embodiment 6. Of course, you can also not specify. Also, according to the method of Embodiment 3, PCE 1 as a PCC can also specify that certain multi-stage multiplexing capabilities (methods) cannot be used on some gateway network elements. Step 502: Using the prior art, the PCE 1 can determine that the Gateway 1 and Gateway 3 are passed through the end-to-end ODU0 service. However, since the PCE 1 cannot see the topology information of the ODU3 Network 2 network, the Gateway 1 and the Gateway 3 cannot be calculated. The routing information in the ODU3 Network 2; only the routing information of this layer can be determined, so the PCE 1 encapsulates the routing information into the ERO object, that is, the ERO object shown in FIG. 11, which includes 1, 3, Gateway 1, 4 , 6, 7, Gateway 3, 9, 10 and other sub-objects, and pass the gateway network elements (Gateway 1 and Gateway 3) determined by the PCE through the ERBO. After PCE1 calculates the route, it needs to return the route to PCC (here, node 1).

Step 503: After the signaling of the end-to-end connection arrives at Gateway 1, create an end-to-end to be established between the two associated pair of gateway network elements (Gateway 1 and Gateway 3). A higher rate ODUj (such as ODU2 or ODU1) connected by ODUi (such as ODU0) is connected (i<j), so Gateway 1 requests PCE 2 to calculate a tunnel between Gateway 1 and Gateway 3, ODU3 Network 2 network. .

Step 504: After the PCE 2 receives the request of the Gateway 1, calculate a tunnel between the Gateway 1 and the Gateway 3 that carries the ODU0 service. Since Gateway 3 supports only two-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 for ODU0 services, although Gateway 1 supports multiplexing and demultiplexing capabilities of ODU0-ODU1-ODU3 and ODU0-ODU2-ODU3, ODU0 is required. The service passes through the ODU3 Network 2 network. PCE 2 can only select the multi-stage multiplexing and demultiplexing capabilities of ODU0-ODU2-ODU3 on Gateway1 and Gateway 3 for the end-to-end ODU0 service. PCE 2 calculates a route between Gateway 1 and Gateway 3 within an ODU3 Network 2 network: Gateway 1, 4, 6, 7, Gateway 3

Step 505: The PCE 2 encapsulates the calculated routing information Gateway 1, 4, 6, 7, and Gateway 3 into the ERO object, and returns to the Gateway 1 through the PCRep message. As shown in FIG. 11, in the sub-objects of Gateway 1 and Gateway 3, the multi-level multiplexing capability selected on the corresponding gateway network element is identified, that is,

Gateway 1 selected: ODU0-ODU2-ODU3;

Gateway 3 selected: ODuO-ODU2-ODU3.

Specifically, the HOP-ATRIBUTES Sub-TLV in the ERO object carries the multi-stage multiplexing capability selected by the corresponding gateway network element. In other scenarios, the invention is equally applicable. For example, PCE 1 only knows the topology information of ODU2 network1; PCE2 only knows the topology information of ODU3 Network 2 and ODU2 Network 3. In the end-to-end route calculation, since PCE1 cannot calculate a route between Gateway 1 and node 10, PCE1 requests PCE2 to calculate a piece between Gateway 1 and node 10 through PCReq when PCE1 and PCE2 can communicate with each other. Routing, the request can carry the specified multi-stage multiplexing capability, and PCE2 returns the routing calculation result to PCE1 through PCRep.

When PCE1 and PCE2 are not in communication with each other, after the end-to-end connection establishment signaling reaches Gateway 1, the gateway 1 requests the PCE2 to calculate a route between the gateway 1 and the node 10 through the PCReq, and the request can carry the specified multi-level complex. With the ability, PCE2 returns the result of the calculation to Gateway 1 via PCRep.

In another embodiment of the present invention, more PCEs may be included in the network. For example, PCE1 only knows the ODU 2 Network 1 topology information, PCE2 only knows the ODU3 Network 2 topology information, and PCE3 only knows the ODU2 Network 3. The route calculation method is similar. When PCE1, PCE2, and PCE3 can communicate with each other, the three PCEs cooperate with each other to complete the end-to-end route calculation; the three PCEs that cannot communicate with each other can also calculate the route for the managed network by itself.

Example 6

The prior art Request for Comments (RFC) 4874 standard describes two types of route exclusion:

1. Exclude specific abstract nodes or resources from the entire path. This collection of abstract nodes is called the Exclude Route List.

2. Exclude abstract nodes or resources between a pair of abstract nodes specified in the display path, called Explicit Route Exclusion.

The prior art Internet Engineering Task Force (IETF) working group document (draft-ietf-pce-pcep-xro-02.txt) defines a protocol extension that allows the PCC to specify the two exclusion types described above. It defines a new Path Computation Element Protocol (PCEP) object, excluding the Exclude Route Object (XRO), to pass the Exclude Route List information. Modify the existing IRO object in PCEP and reference a new IRO sub-object EXRS (Explicit Exclusion Route Sub-Object) to pass the Explicit Route Exclusion information. In the PCReq message, the PCC can specify a number of multiplexed capabilities that pass through some of the gateway network elements and that are used or not used by the passing gateway network elements. Of course, different gateway network elements can also be assigned different multi-level multiplexing capabilities with or without use. This embodiment details how to extend the PCReq protocol to meet the above requirements.

When specifying that some gateway network element must pass, the IRO object in the PCReq of the PCEP protocol may include these gateway network elements, and in the sub-object of each gateway network element, immediately follow the node (node) identifier or interface (interface) After the index identifier sub-object, a HOP-ATTRIBUTE object is inserted, which contains the PCC as the designated gateway network element or the interface on the network element, and the multi-stage multiplexing capability selected for the connection being established. It is also possible to insert a HOP-ATTRIBUTE object in the sub-object of each gateway network element, followed by the node identifier or the interface index identifier sub-object, and the object contains the PCC as the specified gateway network element. Or the interface on the network element, the multi-level multiplexing capability that cannot be selected for the connection being established. To this end, in this embodiment, a detailed coding mode is given to the HOP_ATTRIBUTE object, as shown in FIG. 13, where HOP_ATTRIBUTE includes a Type field, a Length field, an F field (flag field), and The multi-level multiplexing capability information field, and the HOP-ATTRIBUTE object specified or not selected is encoded in the same way, except that the specific values of the F field are different, and the definitions of other fields are the same, as shown in FIG. among them:

HOP—Type field of ATTRIBUTE, indicating the type of the object. The value is 4, which is only an example here. Other values can be used as the value of the type field as needed.

a Length field, configured to indicate a length of the flag field and the multi-level multiplexing capability information field;

The F field (flag field) is used to indicate that the subsequent multi-stage multiplexing capability must be selected or cannot be selected. One value is: 0 means must not be selected, 1 means must be selected; multi-stage multiplexing The capability information field includes M subfields, each of which indicates a multi-level multiplexing capability; M is the number of multi-level multiplexing capabilities specified, and each subfield includes a multi-level multiplexing layer information (Num) field and Multi Stages Multiplexing Sub-TLV fields, denoted by Num i and Multi Stages Multiplexing Sub-TLV i, respectively, i = 1...M.

For example, Num 1 represents a multi-level multiplexing level of the first multi-stage multiplexing capability specified, and Multi Stages Multiplexing Sub-TLV 1 represents a multi-stage multiplexing signal type of the first multi-stage multiplexing capability specified; Num 2 represents the level of multi-level multiplexing of the specified second multi-stage multiplexing capability, Multi Stages Multiplexing Sub-TLV 2 represents the signal type of the multi-stage multiplexing of the specified second multi-stage multiplexing capability; and so on, Num M represents the hierarchical level of the multi-level multiplexing of the specified Mth multi-stage multiplexing capability Multi Stages Multiplexing Sub-TLV M indicates the signal type of the multi-stage multiplexing of the Mth multi-stage multiplexing capability specified.

Among them, Num can be represented by three bits. Each signal type in the Multi Stages Multiplexing Sub-TLV M field is represented by four bits. The specific number of bits can be determined as needed, and the present invention does not limit this.

For example, to indicate the first multi-stage multiplexing capability ODU0-ODU2-ODU3, Num 1 is filled in 2, and then every 4 bits represent an ODUk (k=0, 1, 2, 2e, flex, 3, 4), there are three such 4 bits.

Num 2 represents the hierarchical level of the multi-level multiplexing of the specified second multi-stage multiplexing capability. For example, when ODU0-ODU1-ODU3 is to be represented, Num 2 is filled in 2, and then every 4 bits represent an ODUk.

Among the Multi Stages Multiplexing Sub-TLV i, i=l ... M, 4 bits can be used to represent each signal type as follows:

0000: ODU0

0001 : ODU1

0010: ODU2

0011 : ODU3

0100: ODU4

0101 : ODU2e

0110: ODUflex

The above coding method is only an example, and the present invention does not limit this.

According to the above coding method, the value of the Length field in HOP_ATTRIBUTE is 1+ ( Numl+1 ) *4+ ( Num2+1 ) *4+... ( Num M +1 ) *4+M*3.

Two specific coding embodiments are given below. For example, when multi-stage multiplexing using ODU0-ODU2-ODU3, ODU0-ODU3-ODU4, ODU0-ODU1-ODU2-ODU3-ODU4 is specified for a gateway network element, the specific coding value of HOP-ATTRIBUTES is as shown in FIG. . Among them, the Length in HOP-ATTRIBUTE is 1 + ( 2+1 ) * 4 + ( 2+1 ) * 4 + ( 4+1 ) * 4 + 3 * 3 , and the total length is 54 .

For example, if you specify for a gateway NE, you cannot use ODU0-ODU2-ODU3.

When multi-stage multiplexing of ODU0-ODU3-ODU4, the specific coding value of HOP-ATTRIBUTES is shown in Figure 14. The length in HOP-ATTRIBUTE is 1 + ( 2+1 ) *4+( 2+1 ) *4+2*3 , and the total length is 31.

In the above embodiment, the multi-stage multiplexing capability selected on the gateway network element refers to the multi-stage multiplexing capability selected for the gateway network element. The present invention further provides a path calculation device, the path calculation device is configured to acquire a multi-stage multiplexing capability supported by a gateway network element; and when the receiving path calculates a client end-to-end path calculation request, according to the acquired gateway network element The supported multi-stage multiplexing capability calculates the end-to-end routing, and determines the multi-level multiplexing capability selected by the gateway network element through which the end-to-end routing passes and the gateway network element passing through.

The path calculation device is further configured to: when the path calculation client is a node in a network managed by the path calculation device, the end-to-end route, the gateway network element through which the end-to-end route passes And the multi-stage multiplexing capability selected on the gateway network element passed through is returned to the path calculation client.

The path calculation device is further configured to: when the path calculation client is another path calculation device, save the end-to-end route, the gateway network element through which the end-to-end route passes, and the gateway network passing through The multi-level multiplexing capability selected on the element and returning a routing key to the path computing client.

The path calculation device is configured to acquire a multi-stage multiplexing capability supported by the gateway network element by using a routing protocol or a configuration of the receiving management plane to the path computing device.

The path calculation device is configured to: when the end-to-end path calculation request specifies a multi-stage multiplexing capability that is used or cannot be used by all gateway network elements on the end-to-end route, according to the end The multi-stage multiplexing capability used by the gateway network element or the multi-stage multiplexing capability supported by the gateway network element on the end-to-end route specified in the end-path request, and the end-to-end routing The gateway network element selects a specific multi-stage multiplexing capability. The path calculation device is configured to: when the end-to-end path calculation request explicitly specifies the gateway network element to which the end-to-end route passes and the gateway network element to pass through, or cannot be used. In the multi-stage multiplexing capability, the multi-stage multiplexing capability to be used or not used on the gateway network element to be passed in the request and the gateway network element to be passed in the request, and the gateway network element are calculated according to the end-to-end path The supported multi-stage multiplexing capability calculates the end-to-end routing and selects a specific multi-stage multiplexing capability for the gateway network element on the end-to-end routing.

One of ordinary skill in the art will appreciate that all or a portion of the steps above may be accomplished by a program to instruct the associated hardware, such as a read-only memory, a magnetic disk, or an optical disk. Alternatively, all or part of the steps of the above embodiments may also be implemented using one or more integrated circuits. Correspondingly, each module/unit in the above embodiment may be implemented in the form of hardware or in the form of a software function module. The invention is not limited to any specific form of combination of hardware and software.

Industrial applicability

The G.709-based multiplexed route calculation method and the path calculation device provided by the present invention implement the end-to-end multi-stage multiplexed route calculation by introducing the gateway network element, thereby laying a foundation for interconnecting and interworking between networks. The foundation.

Claims

Claim

A G.709-based multiplexed route calculation method, which is applied to an optical transport network including a gateway network element, where the method includes:

2. The method according to claim 1, wherein, when the path calculation unit receives the end-to-end path calculation request of the path calculation client, the multi-stage multiplexing capability supported by the obtained gateway network element is calculated. After the routing, and determining the gateway network element through which the end-to-end route passes and the step of selecting the multi-stage multiplexing capability for the gateway network element, the method further includes:

3. The method according to claim 1, wherein, when the path calculation unit receives the end-to-end path calculation request of the path calculation client, the multi-stage multiplexing capability supported by the obtained gateway network element is calculated. After the routing, and determining the gateway network element through which the end-to-end route passes and the step of selecting the multi-stage multiplexing capability for the gateway network element, the method further includes:

4. The method according to claim 1, wherein in the step of the path calculation unit acquiring the multi-stage multiplexing capability supported by the gateway network element,

5. The method according to any one of claims 1 to 4, wherein

Determining, in the end-to-end path calculation request, a multi-stage multiplexing capability of all gateway network elements through which the end-to-end route passes or cannot be used;

Calculate end-to-end routing based on the acquired multi-level multiplexing capabilities supported by the gateway network element, and determine In the steps of the gateway network element through which the end-to-end route passes and the multi-stage multiplexing capability selected for the passed gateway network element,

The path calculation unit calculates, according to the end-to-end path, the multi-stage multiplexing capability that is used or not used by all the gateway network elements that the end-to-end route passes in the request and the multi-level complex supported by the gateway network element. The capability is to select a multi-stage multiplexing capability for the gateway network element on the end-to-end route.

6. The method according to any one of claims 1 to 4, wherein

The end-to-end path calculation request explicitly specifies a gateway network element through which the end-to-end route passes and a multi-stage multiplexing capability to be used or not available for the gateway network element to pass through;

7. The method according to claim 6, wherein the end-to-end path calculation request specifies a gateway network element to which the end-to-end route passes and selects whether to use or cannot use the gateway network element to pass through. The steps of the level multiplexing capability include:

a type field indicating the type of the attribute object;

A path calculation device, the path calculation device is configured to acquire a multi-stage multiplexing capability supported by a gateway network element; and when the reception path calculates a client end-to-end path calculation request, according to the obtained gateway network element support The multi-stage multiplexing capability calculates end-to-end routing, and determines the gateway network element through which the end-to-end route passes and selects multi-stage multiplexing capability for the passed gateway network element.

9. The path computing device of claim 8, the path computing device further configured to: when the path computing client is a node in a network managed by the path computing device, routing the end-to-end, The gateway network element through which the end-to-end routing passes and the multi-stage multiplexing capability selected for the passed gateway network element are returned to the path calculation client.

10. The path computing device of claim 8, the path computing device further configured to: save the end-to-end route, the end-to-end route when the path calculation client is another path computing device The passed gateway network element and the multi-stage multiplexing capability selected for the passed gateway network element, and returns a routing key to the path calculation client.

The path calculation device according to claim 8, wherein the path calculation device is configured to: acquire a multi-stage multiplexing capability supported by the gateway network element by using a routing protocol or a configuration of the path management device by the receiving management plane.

12. A path calculation device according to any of claims 8 to 11,

The path calculation device is configured to: when the end-to-end path calculation request specifies a multi-stage multiplexing capability that is used or cannot be used by all gateway network elements through which the end-to-end route passes, according to the end-to-end The multi-stage multiplexing capability of the gateway network element that is used by the end-to-end route specified by the path calculation request or the multi-stage multiplexing capability supported by the gateway network element, and the end-to-end routing The gateway network element selects multi-level multiplexing capability.

13. The path calculation device according to any one of claims 8 to 11,

The path calculation device is configured to: when the end-to-end path calculation request explicitly specifies the gateway network element to which the end-to-end route passes, and select a gateway network element to pass through to select whether to use or not to use When the level multiplexing capability is performed, the gateway network element to be passed in the request is calculated according to the end-to-end path, the multi-stage multiplexing capability to be used or not used, and the gateway network element selected for the gateway network element to be passed. The supported multi-stage multiplexing capability calculates the end-to-end route and selects multi-stage multiplexing capability for the gateway network element through which the end-to-end routing passes.