KR100392646B1 - Method for determining traffic paths for Protection Switching in MPLS based data telecommunication network - Google Patents

Abstract

In the data communication network of a multi-protocol label switching (MPLS) traffic engineering environment, the present invention provides a primary as a primary path for a corresponding traffic in order to prepare for a network failure when high data quality (QoS) is required. A method for establishing another spare path for protecting switching and bypassing protection switch in the event of a failure of the primary label switch path, together with a label switch path (Primary LSP). Pass through LSRs (LSR1, LSR2, LSR3), and if the repair node 730 is determined, the spare path 703 from the ingress node 710 to the repair node 730, and the repair. By establishing a reserve path 702 from node 730 to egress node 720, bandwidth usage is reduced compared to conventional fast reroute. Teksyeon reduce disaster recovery time when compared with pre-existing path during switching, and are also guaranteed a good living for existing disorder than when you connect the egress node from ingress node to a spare path also.

Description

Method for determining traffic paths for Protection Switching in MPLS based data telecommunication network}

The present invention relates to a traffic path setting method for protection switching in a data communication network to which a multi-protocol label switching scheme is applied, and more particularly, to a multi-protocol label switching (MPLS) traffic engineering environment. In a data communication network, a primary label switched path as a primary path for the traffic in order to prepare for a network failure when a high quality of service (QoS) is required for the transmitted data traffic. In addition, another backup path for bypassing protection switching in case of failure of the primary label switch path is separately set. It relates to a method for setting efficiently.

MPLS provides quality of service (QoS) for transport traffic in a variety of networks, including Internet Protocol (IP-based) networks, including Internet Protocol-based (IP-based) networks, and IP over DWDM networks over DWDM. It is a technology that has been in the spotlight recently as a traffic engineering method for guaranteeing the reliability and efficiently utilizing network resources.

MPLS traffic engineering uses a variety of methods to establish traffic paths, or Label Switched Paths (LSPs), to better accommodate the varying QoS requirements for IP packets of users.

In the MPLS network environment, a backup path for the primary LSP is set to prepare for a link or node failure or partial congestion of the network. Task Force (IETF) The MPLS Working Group discusses two methods, Protection Switching and Fast Reroute.

First, the protection switching method considers a spare path from an ingress node to an egress node for the primary LSP. Next, fast reroute is a method of establishing a reverse path from egress to ingress and a preliminary path from ingress to egress for the primary LSP.

In order to apply the fast reroute scheme, since two additional paths (reverse paths and spare paths) are additionally configured for one primary LSP, network resources are wasted.

Therefore, in order to make up for the shortcomings, a method of reducing the bandwidth usage by the reverse path as much as possible by using a shortcut is being discussed. However, it is pointed out that there are many overhead problems on the router. The advantage is that traffic can be sent in a detour within a very short time when there is a failure on the path that does not guarantee the required quality of service.

The protection switching method is advantageous in terms of bandwidth usage compared to the fast rerouting method, but the failure convergence time is slightly longer, so when setting the primary label switch path and the redundant path to apply the MPLS protection switching method, the bandwidth can be used. There is a need for a study on how to reduce the recovery time while reducing the use of.

The present invention was created to solve the existing problems in the technical background as described above, and its purpose is to provide reliable ingress-to-egress transmission of traffic requiring a high degree of quality of service (QoS). For this purpose, one primary LSP and two spare paths for one end-to-end are determined according to the new method, but when the protection switching method is applied, the failover time can be reduced while reducing the use of bandwidth if possible. It is an object of the present invention to provide a traffic routing method for protection switching in a data communication network to which a multi-protocol label switching scheme is applied.

Also, CR-LDP (Constraint-based Routed LDP) and RSVP (RSVP: Resource ReServation Protocol), which are extensions of the Label Distribution Protocol (LDP) as a protocol for LSP setup of MPLS traffic engineering. RSVP-TE, which is an extended form of RSVP-TE, is being discussed. In the present invention, a protocol for setting a primary LSP and a preliminary route can be used to extend RSVP-TE, which is currently being standardized. For other purposes.

In addition, the cost is calculated by considering the amount of traffic to be transmitted when calculating the link cost or node cost of the network required for determining the routes for the primary LSP and backup path, and the generated costs Another object of the present invention is to optimize and set a desired traffic path by considering a nonlinear cost function such as a delay function with respect to the traffic flow amount.

1 is a diagram illustrating an example of a data communication network to which a multi-protocol label switching (MPLS) scheme is applied;

FIG. 2 is a schematic block diagram of setting a label switching path LSP and a backup path in a label switch router LSR as a label edge router LER and / or a repair node of FIG.

3 shows one primary LSP for transmitting one ingress-to-egress traffic for protection switching in a data communication network to which a multi-protocol label switching (MPLS) scheme according to the present invention is applied. And a diagram illustrating a network in which two backup paths Bp1 and Bp2 are set,

4 is a view showing the form of RIO information as a new object included in an existing path message according to the present invention,

5 is a view showing the form of BRO information as a new object included in an existing path message according to the present invention,

6 is a diagram illustrating RDO information as a new object included in an existing RESV message according to the present invention;

FIG. 7 is a diagram illustrating an embodiment of the present invention for setting one primary LSP and two preliminary paths as shown in FIG. 3 using a message having each object newly defined according to the present invention.

※ Explanation of code for main part of drawing

100: Data communication network with multi-protocol label switching

110,310,710: Ingress Label Edge Router (or Ingress Node)

120,320,720: egress label edge router (or egress node)

130-133,231-235,241,242: Label Switch Router (or Intermediate Node)

301701: Primary Label Switching Path

330,730: Repair node

301,302, 702,703: spare route

In order to achieve the above object, a traffic path setting method for protection switching in a data communication network to which the multi-protocol label switching method is applied according to the present invention is a data communication network to which the multi-protocol label switching (MPLS) method is applied. Ingress-to-end from Label Edge Router (LER) as Ingress Node to Label Edge Router (LER) as Egress Node through Label Switch Router (LSR) as one or more intermediate nodes. Egress) A method for establishing a traffic path (LSP) and a spare path of the traffic path, comprising: removing from the target a link whose nodes are less than the total amount of traffic to be transmitted, out of the total link between the nodes in the network. First step; A second step of calculating a distance information value for each target link remaining as a result of the removal of the first step, based on the information on the amount of traffic currently used on the link and the amount of traffic to be transmitted; A third step of establishing an end-to-end traffic path based on the calculated distance information value; A fourth step of transmitting a first message carrying the state and state information of the link from each of the intermediate nodes on the path from the inlet node to the outlet node through the established end-to-end traffic path; A fifth step of, at the egress node, selecting one of the nodes as a repair node based on state information of each node and a link included in the received first message; A sixth step of transmitting a second message containing identification information of the selected repair node from the exit node that is the reverse of the end-to-end traffic path to the entry node; A seventh step of establishing a first spare path from one node to the exit node in one intermediate node that recognizes that the node is a repair node based on the node identification information of the second message; And an eighth step of recognizing the repair node on the basis of the node identification information of the received second message and establishing a second spare path to the recognized repair node at the entrance node.

The first message is configured by adding the status information to a PATH message based on RSVP-TE (Resource ReServation Protocol Traffic Engineering), and the status information carried on the first message is a corresponding link. Alternatively, the class information may determine the reliability of the node, and includes class information on the spare bandwidth and / or the delay degree.

The fifth step may include selecting a node having the lowest rank of the state information as a repair node, and determining whether the rank of the node having the lowest status rank is less than or equal to a preset threshold; A lower two step of selecting a corresponding node as a repair node if it is less than the determination result; A lower three step of determining whether the total number N of nodes on the path is odd or even if the determination result is abnormal; And if N is an odd number, select a minimum integer th node that is greater than N / 2 divided by 2 as a repair node, and if it is even, repair the node of a ± 1 th node of N / 2 divided by 2 It consists of three sub-steps to choose from.

The second message is configured by adding the identification information to a RESP part based on Resource ReServation Protocol Traffic Engineering (RSVP-TE).

The setting of the first preliminary path in the seventh step or the second preliminary path in the eighth step may include setting a preliminary path from the repair node to the exit node or from the inlet node to the repair node. Information about the priority, maintenance priority of the spare path, reserved resources required for the spare path, and identifiers of nodes on the spare path, to secure intermediate nodes forming the first or second spare path. 3 lower step of transmitting a message; And a second step of transmitting a response message to the third message from the exit node to the repair node or from the repair node to the inlet node in the reverse path of each preliminary path.

The information of the third message is additionally included in a path message based on Resource ReServation Protocol Traffic Engineering (RSVP-TE), and the corresponding response message is a reserve message based on RSVP-TE. It is composed.

In the second step, a derivative value of a delay function value of each corresponding link is obtained based on information on the amount of traffic currently used on the link and the total amount of traffic to be transmitted, and the derivative value of the delay function value is determined by the distance. It is used as an information value.

Hereinafter, a traffic route setting method for protection switching in a data communication network to which a multi-protocol label switching (MPLS) scheme according to an exemplary embodiment of the present invention is applied will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating an example of a data communication network to which the MPLS scheme is applied. The network 100 includes a plurality of routers, and serves as an inlet of the network 100 to any data traffic among the plurality of routers. The router is called an Ingress Label Edge Router (LER) 110, and the router serving as an exit is called an Egress Label Edge Router 120. One or more routers serving as nodes of an intermediate path between the ingress LER 110 and the egress LER 120 are referred to as a label switching router (LSR) 130 and the ingress LER 110 The traffic path established from the LSR 130 to the egress LER 120 is called a Label Switch Path (LSP) (LSP1, LSP2). The LSP is an ingress LER 110. Set for incoming traffic , In the figure, for example LSP1 is to say the path set as 110 → 132 → 133 → 120, LSP2 refers to a path set as 110 → 131 → 120.

FIG. 2 is a schematic block diagram for setting up an LSP and a spare path at an ingress LER and / or a repair node, and includes an input / output interface 201 and a physical switching structure that serve as a data communication interface with an external device. 202, a memory 203 storing a routing table, a routing table stored in the memory 203, and controlling the switching structure 202 according to the created and stored routing table to control the input / output interface 201. The control unit 204 is configured to control the input / output of traffic, and the LSP and the spare path as described above when the routing table is stored in the memory 203 under the control of the control unit 204. Is set. Therefore, the present invention described below is applied to the control unit 204 and implemented.

3 shows one primary LSP for transmitting one ingress-to-egress traffic for protection switching in a data communication network to which a multi-protocol label switching (MPLS) scheme according to the present invention is applied. 301 and two backup paths 302 and 303, the primary LSP 301 is an Ingress LER 310 → LSR1 → LSR2 330 → LSR3 → Egress LER 320 The first preliminary path 302 is set as a preliminary path from the ingress LER 310 to the LSR2 330, and the second preliminary path 303 is set as the egress LER (L) from the LSR2 330. As an example, the case of setting the spare path up to 320 is shown.

In FIG. 3, LSR2 is a repair node 330. As such, the repair node is selected from among the pass-through LSRs as intermediate nodes through which the LSP passes. When the repair node is determined, the preliminary path 302 from the ingress LER 310 to the repair node 330 and the preliminary path 303 from the repair node 330 to the egress LER 320 are set. This reduces bandwidth usage compared to Fast Reroute and reduces failover convergence time when compared to Protection Switching. In addition, better survival against disability is ensured than in the case of ingress, which connects egress to a single reserve path.

In the present invention, the message based on the existing RSVP-TE is used for the LSP configuration as shown in FIG. That is, the present invention defines a new function object called Route Information Object (RIO), Backup Path Route Object (BRO), and Repair Node Designate Object (RDO). The defined RIO and BRO information is included in addition to the existing RSVP-based pass message, and the RDO information is included in the existing RSVP-based reservoir (RESV) message.

4 is a view illustrating a form of the RIO information included in an existing path message, and includes length, class-num, type-C, and addresses of intermediate nodes via the primary LSP. Intermediate ID, which indicates each node through its state and the state of the link, and stores the state information of the link and node via the primary LSP to inform the egress node. The information is configured to include information about state information.

FIG. 5 is a view illustrating a form of the BRO information included in an existing path message, and indicates a priority for securing resources by indicating a priority setting of a backup path, and is represented by, for example, 0 to 7. FIG. 0 indicates the maintenance priority for resources in the setup priority and backup path with 0 being the highest priority. For example, 0 to 7 with 0 being the highest priority. (Hold priority), Reserved Bandwidth (Reservation Bandwidth) indicating the reservation resources required for the Backup Path, and Downstream node ID (ID) indicating the ID of the LSR through which the reserve path passes. Consists of.

FIG. 6 illustrates the RDO information included in the existing RESV message, and plays an important role in setting up a preliminary path, and includes length, class-num, type, and repair. It is configured to include information about the node ID (Repair node ID).

The repair node ID information is a value indicating a repair node (LSR2) 330 which is an end point for one spare path 302 and a start point for another spare path 303, as in LSP2 of FIG. That is, if the LSR received the corresponding message compares its ID with the repair node ID, it sets a preliminary path from itself to the egress LER. Similarly, when the message arrives at the ingress LER, a preliminary path from the ingress LER to the repair node is set.

For reference, in the form of the object information of FIGS. 4 to 6 defined as described above, each row is 32 bits and has the same size as that of the object of the existing RSVP pass message.

Next, an embodiment of the present invention will be described, but using the message having each newly defined object according to the present invention (see FIGS. 4 to 6) as described above, one primary LSP ( The procedure of the present invention for establishing 301 and two preliminary paths 302 and 303 will be described in detail with reference to FIG.

First, a path for the primary LSP 701 is determined as shown in FIG. The path decision is made by using an existing LSP path determination method or by the following method.

The current traffic transmission margin among the network G (m, n) having the entire link consisting of nodes and nodes (for example, between 110 and 131, between 132 and 133, etc.) of the communication network 100 configured as shown in FIG. Create a network G (d) by removing links from the destination whose capacity Ci is less than the total amount of traffic d to be transmitted at present. m represents the number of links, n represents the number of nodes.

For each link i of the network satisfying the G (d), a distance information value dist (i) is obtained based on information on the current traffic amount y _i and the total traffic amount d to be transmitted. For example, when the yi and d information is used as a variable of the delay function f _i (x _i ) as a cost function for each link, the distance information value dist (i) is a delay function f _i (y based on Equation 1 below. _{Since i} + d) is defined as the result of the derivative function f _i '(y _i + d), the corresponding distance information value is obtained using Equation 1 and y _i and d value information.

In Equation 1, i denotes a corresponding link (i = 1, ..., m) (m = total number of links), dist (i) is a distance information value of the link i, tc _i is the link i The initial capacity, y _i is the amount of traffic currently being used on link i, c _i is the current spare capacity of link i, and a relationship of "c _i = tc _i -y _i " is established. In addition, if the delay function representing the delay at each link i is f _i (x _i ), the expression "f _i (x _i ) = x _i / (tc _i -x _i )" is established, where xi is the link i. The amount of traffic passing through. If the delay function is f _i (x _i ), the derivative of f _i '(x _i ) is "f _i ' (x _i ) = c _i / (tc _i -x _i ) ² ". do. Thus, the equation (1) represents the resulting expression into a cleanup for y _i + d in the variables x _i in place of the delay function f _i a function derivative of _{(x i) f i '(} x i). That is, f _i (x _i) was used as the delay function as an example of a cost function as described above in the present embodiment as generating a cost function for when the flow rate of the link _{i x i, f i '(} x i) is a link An increase cost function per unit flow when the flow amount of _i is x _i , which is the derivative of the delay function. For reference, although the delay function is used as an example, the cost function is not limited thereto. The cost function may be a function for obtaining distance information on a link based on information about yi and d.

As described above, the first end-to-end traffic path (hereinafter referred to as LSP1) is established based on the distance information value calculated for each link i. If the LSP1 is found in plural numbers, the calculated delay is determined. Only one LSP is set to the primary LSP 701 based on the principle of setting a link having a relatively small function value, that is, a distance information value as a traffic path.

Subsequently, an RSVP-TE based path (PATH) message including the RIO object shown in FIG. 4 is sent from the ingress node 710 to the egress node 720. In the RIO state information, a rating indicating a degree of network reliability, such as a free bandwidth and a delay degree, of a link or node LSR1, LSR2, LSR3 through which the primary LSP 701 passes, is recorded. The better the reliability, the higher the rating.

Next, the egress node 720 receiving the pass message prepares information for an RSVP-TE based reserve (RESV) message including an RDO object as shown in FIG. 6 based on the RIO information included in the pass message. Here, the egress node 720 determines the repair node recorded on the RDO in the following manner. Below the threshold may be any value defined by the user.

First, the node having the lowest rank among each node or link passing through the primary LSP 701 is found based on the RIO information of the received pass message, and if the rank of the node is less than or equal to the threshold, the node is a repair node. . Second, if the lowest value is greater than or equal to the threshold, the repair node is determined as follows. If N is odd, the minimum integer node larger than N / 2 is determined as the repair node. If N is even, the node (N / 2) ± 1 is determined as the repair node. Here, the ingress node is the first node and the egress node is the Nth node along the primary LSP 701, and the total number of nodes on the primary LSP 701 is N. In this embodiment, it is assumed that LSR2 is determined as a repair node in the above manner.

Next, the egress node 720 records the ID of the repair node LSR2 determined as described above in the corresponding column of the RDO object, and writes a reserve (RESV) message including the RDO information to the intermediate nodes LSR3, LSR2, It transmits to the ingress node 710 via LSR1 sequentially.

As described above, the LSR2 designated as the repair node receives the reserve message and recognizes that it is a repair node based on the ID of the RDO information included in the reserve message being the same as its ID. As shown, the LSR2 designated as a repair node determines a path from itself to the egress node 720 (which uses an existing known method or a method when determining the primary LSP 701 in the present invention), A first preliminary path 702 is set using a pass message including a BRO as shown in FIG. 5 and a RESU message generated in response thereto.

That is, the process of setting the first spare path may include setting priority of spare paths, priority of maintaining spare paths, reserved resources necessary for spare paths from the repair node LSR2 to the egress node 720. Sending the pass message including the BRO having information on the identifiers of the nodes on the spare path to secure intermediate nodes that make up the first preliminary path, wherein the intermediate nodes receiving the pass message are configured based on the BRO information. The path to the egress node 720 is set.

Finally, upon receipt of the reserve message, the ingress node 710 sees the repair node ID on the RDO information included in the reserve message and recognizes that the corresponding repair node is the LSP2. Calculate the LSP going to the designated repair node (LSP2) (which is the known method or the method when determining the primary LSP 701 in the present invention) and the same method as when setting up the first spare path 702 As shown in FIG. 5, the second preliminary path 703 is set using a pass message including a BRO and a reserve message generated in response thereto.

As described in detail above, a traffic path setting method for protection switching in a data communication network to which a multi-protocol label switching (MPLS) scheme according to the present invention is applied may include a repair node from among LSRs passing through a repair node. When the repair node is selected, the backup path from the ingress node to the repair node and the spare path from the repair node to the egress node are set to provide a bandwidth compared to the existing fast reroute. Reduced use, reduced failover convergence time when compared to traditional spare paths in Protection Switching, and the existing case of connecting egress nodes to one spare path from ingress nodes Better survival is ensured against disability. In addition, when calculating the link or node cost required for path determination, the traffic flow and the nonlinear cost function are considered to enable optimal path setting.

Claims (11)

In a data communication network with a multi-protocol label switching (MPLS) scheme, a label edge as an egress node from a label edge router (LER) as an ingress node through a label switch router (LSR) as one or more intermediate nodes. In a method for setting up an ingress-to-egress traffic path (LSP) to a router (LER) and a spare path of the traffic path, A first step of removing links from nodes and nodes in the communication network, in which the capacity of the current traffic transmission capacity is less than the total amount of traffic to be transmitted, from the target; A second step of calculating a distance information value for each target link remaining as a result of the removal of the first step, based on the information on the amount of traffic currently used on the link and the total amount of traffic to be transmitted; A third step of establishing an end-to-end traffic path based on the calculated distance information value; A fourth step of transmitting a first message carrying the state and state information of the link from each of the intermediate nodes on the path from the inlet node to the outlet node through the established end-to-end traffic path; A fifth step of, at the egress node, selecting one of the nodes as a repair node based on state information of each node and a link included in the received first message; A sixth step of transmitting a second message containing identification information of the selected repair node from the exit node that is the reverse of the end-to-end traffic path to the entry node; A seventh step of establishing a first spare path from one node to the exit node in one intermediate node that recognizes that the node is a repair node based on the node identification information of the second message; And And an eighth step of recognizing the repair node based on node identification information of the received second message and establishing a second spare path to the recognized repair node at the inlet node. -Traffic routing method for protection switching in a data communication network to which protocol label switching is applied. The method of claim 1, The first message is a data communication network to which a multi-protocol label switching scheme is applied by adding the state information to a PATH message based on RSVP-TE (Resource ReServation Protocol Traffic Engineering). Traffic Routing Method for Protection Switching The method according to claim 1 or 2, The state information carried in the first message is class information for determining reliability of a corresponding link or node, and includes multi-protocol label switching scheme, which includes class information on a spare bandwidth and / or a delay degree. Traffic routing method for protection switching in the applied data communication network. The method of claim 1, The fifth step is a traffic path setting method for protection switching in a data communication network to which a multi-protocol label switching scheme is selected, wherein the node having the lowest level of status information is selected as a repair node. The method of claim 1, The fifth step, A first step of determining whether a class of a node having the lowest state class is less than or equal to a preset threshold; A lower two step of selecting a corresponding node as a repair node if it is less than the determination result; A lower three step of determining whether the total number N of nodes on the path is odd or even if the determination result is abnormal; And If N is an odd number, N is divided by 2, and a minimum integer node larger than N / 2 is selected as a repair node, and if even, N is divided by 2, a ± 1 th node of N / 2 is a repair node. A method of establishing a traffic route for protection switching in a data communication network to which a multi-protocol label switching scheme is applied, comprising: selecting the lower three steps. The method of claim 1, The second message is a data to which the multi-protocol label switching scheme is applied, wherein the identification information is configured by adding the identification information to a RESP part based on Resource ReServation Protocol Traffic Engineering (RSVP-TE). Traffic routing method for protection switching in a communication network. The method of claim 1, The setting process of the first preliminary path or the second preliminary path may include: From the repair node to the exit node or from the inlet node to the repair node, information on the priority setting of the spare path, the maintenance priority of the spare path, the reservation resources required for the spare path and identifiers of the nodes on the spare path are provided. A first step of transmitting a third message for securing intermediate nodes forming the first preliminary path or the second preliminary path; And And a second step of transmitting a response message to the third message from the exit node to the repair node or from the repair node to the inlet node in the reverse path of each preliminary path. A traffic routing method for protection switching in a data communication network to which protocol label switching is applied. The method of claim 7, wherein The information of the third message is additionally included in a path message based on Resource ReServation Protocol Traffic Engineering (RSVP-TE), and the corresponding response message is a reserve message based on RSVP-TE. A traffic route setting method for protection switching in a data communication network to which a multi-protocol label switching scheme is applied. The method of claim 1, In the second step, a derivative value of a delay function value of each corresponding link is obtained based on information on the amount of traffic currently being used on the link and the total amount of traffic to be transmitted, and the derivative value of the delay function value is respectively determined by the distance information. A traffic routing method for protection switching in a data communication network using a multi-protocol label switching method, characterized in that it is used as a value. The method of claim 9, The distance information value is, Where i denotes the corresponding link (i = 1, ...., m) (m = total number of links), and dist (i) is the distance information of link i, tc _i Is the initial capacity of link i, y _i is the amount of traffic currently in use on link i, ci is the current spare capacity of link i, and a relationship of "c _i = t _ci -y _i " is established, and d is the total to be transmitted. A traffic routing method for protection switching in a data communication network to which a multi-protocol label switching scheme is applied, wherein the traffic volume is represented. The method of claim 10, In the third step, when there are a plurality of end-to-end traffic paths, a data communication network to which a multi-protocol label switching scheme is applied is configured to set a link having a relatively small calculated distance information as a traffic path. Traffic Routing Method for Protection Switching