KR100392649B1 - Method for determining paths of traffic for Protection Switching and/or Fast Reroute in MPLS based data telecommunication network - Google Patents

Abstract

According to the present invention, in a data communication network of a multi-protocol label switching (MPLS) traffic engineering environment, a network failure occurs when a high quality of service (QoS) is required for transmitted data traffic. In order to be prepared, another primary backup path for protection switching or fast rerouting in case of failure of the primary label switch path, together with the primary label switched path as the primary path for the traffic, A method for efficiently setting such a primary label switch path and a backup path is provided. The link or node cost function (for example, a delay function) is based on the flow of traffic to be transmitted. The flow of traffic you want to calculate Because on the basis of a non-linear cost function taking into account the setting up the primary and backup LSP path, it is possible to determine an optimized path for protection switching and / or fast reroute.

Description

Method for determining paths of traffic for Protection Switching and / or Fast Reroute in MPLS based data telecommunication network}

The present invention relates to a traffic routing method for protection switching and / or fast rerouting in a data communication network to which a multi-protocol label switching scheme is applied. More specifically, the present invention relates to multi-protocol label switching. MPLS) In a data communication network in a traffic engineering environment, a primary label switch as a primary path for the traffic in order to prepare for a network failure when a high quality of service (QoS) is required. Along with the primary label switched path, another backup path for protecting switching or fast rerouting in case of failure of the primary label switch path is separately set. To efficiently set backup and backup paths It relates to the law.

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 establishes traffic paths, or Label Switched Paths (LSPs), in a variety of ways to better accommodate the various QoS requirements of IP packets of users.

Traffic flows of users requiring transmission are classified into Forwarding Equivalent Classes (FECs) determined according to the service provider's QoS policy based on a service level agreement (SLA), and an LSP is set. .

There are also a variety of ways for service providers to map various QoS requirements of users to the QoS policies they provide. In particular, when traffic having a very important QoS, for example, packet loss, has a sensitive effect on quality of service, the LSP should be set more robustly.

That is, the Internet Engineering Task Force (IETF) MPLS Working Group is required for the traffic requiring high quality, as well as the congestion of the network and stable traffic transmission even in the event of a node or link failure. Working Group (WG) considers Fast Reroute and Protection Switching methods, and standardization is in progress, and Fast Reroute and Protection Switching are being considered. As a specific method for the research on the setting method of the primary LSP having a backup path (Backup path) is actively in progress.

However, the link or node costs considered in the methods discussed so far or in the existing routing methods consider only the traffic flow in a given state without considering the traffic flow required for transmission at present, and are mostly linear. Considering only the cost function type, it is difficult to optimize the route from the network-wide perspective, resulting in inefficient traffic engineering efficiency.

The present invention has been made to solve the above problems, and its object is to provide a primary label switching path as a primary path for stable end-to-end transmission of traffic requiring a high degree of quality of service (QoS). P-LSP) and the backup path as a spare path in case of failure, according to a new method, in particular the link cost of the network required when determining the Routes for Primary LSP and Backup path, or In calculating the node cost, the cost is calculated by considering the amount of traffic flow to be transmitted, and the incurred cost is calculated by considering the nonlinear cost function such as the delay function for the traffic flowing through the link or node. Multi-protocol Label Switching (MPLS) for Data Path Optimization It is an object of the present invention to provide a traffic routing method for protection switching and / or fast reroute.

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 diagram illustrating an example of a protection switching and / or fast reroute method in a data communication network to which a multi-protocol label switching (MPLS) scheme is applied.

FIG. 3 is a schematic block diagram of setting a label switching path LSP and a backup path in the label edge router LER of FIGS. 1 and 2;

4 is a flowchart illustrating a method for establishing a traffic path for protection switching and / or fast reroute in a data communication network to which the MPLS scheme is applied according to an embodiment of the present invention.

※ Explanation of code for main part of drawing

100: Data communication network with multi-protocol label switching

110,210: Ingress Label Edge Router

120220: Egress Label Edge Router

130-133,231-235,241,242: Label Switch Router

P-LSP: Primary Label Switching Path

Bp: backup path

In order to achieve the above object, a traffic routing method for protection switching and / or fast rerouting in a data communication network to which the multi-protocol label switching method is applied according to the present invention is a multi-protocol label switching (MPLS) method. In an applied data network, end-to-end from a Label Edge Router (LER) as an Ingress to a Label Edge Router (LER) as an Egress through a Label Switch Router (LSR) as one or more intermediate nodes. A method of establishing an ingress-to-egress traffic path (LSP), comprising: a first step of removing from a target a link of nodes in the communication network whose links are less than the total amount of traffic that can be transmitted by current free traffic. ; A second step of calculating a first 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 a first end-to-end traffic path based on the calculated first distance information value; A fourth step of removing from the object of the link between the node and the node of the communication network the link which constitutes the first end-to-end traffic path and the link whose current capacity for transmitting traffic is less than the total amount of traffic to be transmitted; A fifth step of calculating a second distance information value for each target link remaining as a result of the removal of the fourth 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 sixth step of setting a second end-to-end traffic path based on the calculated second distance information value; And determining the set first end-to-end traffic path as a primary label switching path to allocate all traffic to be transmitted, and using the set second end-to-end traffic path as a backup path. It is configured to include.

The second step or the fifth step obtains a first or second delay function value of each corresponding link based on the information on the amount of traffic currently used on the link and the total amount of traffic to be transmitted, and the first or second delay function value. The derivative value of the second delay function value is used as the first or second distance information value.

Further, in the third and sixth steps, when there are a plurality of first or second end-to-end traffic paths, a link having a relatively small calculated distance information value may be set as a traffic path. It is done.

The backup path set by the method of the present invention is a repair node when a protection switching scheme is applied when a failure occurs to any link or node on the primary LSP. ) (Generally LER as an ingress node) to an egress node, and when the fast reroute method is applied, it is from ingress to egress. Used as a bypass route to). That is, the present invention effectively determines the traffic path for the primary label switch path (Primary LSP) and the backup path (Backup path). By using the path determining method of the present invention, an effective backup path and primary LSP setting capable of protecting traffic from network failure are possible, and the method of the present invention is applied in an MPLS router or a switch.

Hereinafter, a method of establishing a traffic route for protection switching and / or fast reroute 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. do.

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 is set to 110 → 132 → 133 → 120, LSP2 refers to a path set as 110 → 131 → 120.

FIG. 2 is a diagram illustrating an example of a protection switching and / or fast reroute method in a data communication network to which a multi-protocol label switching (MPLS) scheme is applied. As shown in FIG. Primary LSPs (hereinafter referred to as P-LSPs) via a plurality of LSRs 231 to 235 are set between the egress LER 220 and the traffic is transmitted, and the ingress LER 210 and the egress LER are established. When a backup path Bp through LERs 241 and 242 is set as a spare path for the P-LSP between the 220 and the link between the LSR 233 and the LSR 234, the backup path ( Bp) is a repair node that receives a failure report from the LER 233 as shown in FIG. 2 (b) if protection switching is applied (in this case, an ingress LER is a repair node). Detour from 210 to Egress node 220 When used as the furnace 240 and the fast reroute method is applied, the detour path from the ingress 210 to the egress 220 as shown in FIG. 250).

3 is a schematic block diagram for setting an LSP and a backup path in an ingress SER such as the LER 110 of FIG. 1 or the LER 210 of FIG. 2, and serves as a data communication interface with an external device. Input / output interface 301, a physical switching structure 302, a memory 303 for storing a routing table, a routing table stored in the memory 303, and the switching structure according to the created and stored routing table ( Control unit 302 is configured to control the input / output of the traffic via the input / output interface 301, and is stored in the memory 303 under the control of the control unit 304 The LSP as described above is also set when the routing table is created. Therefore, the present invention described below is applied to the control unit 304 and implemented.

FIG. 4 is a traffic path establishment method for protection switching and / or fast reroute in a data communication network to which the MPLS scheme is applied according to an embodiment of the present invention. It illustrates the flow chart that describes the physical topology of the network, the cost function (e.g., delay function), the initial and spare capacity of the network link, and the traffic demand for the traffic requiring the current LSP (i.e. , The total amount of traffic to be transmitted) and the like are already known to the ingress LER to which the present invention is applied, and routers (LSRs) on the MPLS network are also aware of the information.

First, the current capacity of the current traffic transmission in 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. ) Currently removes the links that are less than the total amount of traffic d to be transmitted (S401). In the same figure, G1 of step S401 indicates a network in which a link having a free capacity less than d is removed from the current network G (m, n). m represents the number of links, n represents the number of nodes.

Subsequently, a first distance information value dist (i) is obtained for each link i of a network satisfying the G1 based on information on the current traffic amount y _i and the total traffic amount d to be transmitted. When the yi and d information is used as a variable of a delay function f _i (x _i ) as an example of a cost function for each link, the first distance information value dist (i) is a delay function f based on Equation 1 below. _{Since i} (y _i + d) is defined as the result of the derivative function f _i '(y _i + d), the corresponding distance information value is obtained by using Equation 1 below and y _i and d value information. S402).

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 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. 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 ) is an incurring cost function when the flow amount of link i is xi. In this embodiment, a delay function is used as an example of the cost function as described above, and f _i '(x _i ) is link i. the flow amount in the x _i be when increased flow per unit cost function in this case shows a differential function 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.

Next, the first end-to-end traffic path (hereinafter referred to as LSP1) is established based on the first distance information value calculated for each link i as described above. Only one LSP1 is set based on the principle of setting a link having a relatively small first delay function value, that is, the first distance information value, as a traffic path (S403).

Next, when one LSP1 is set in step S403, the link and the first end-to-end of the surplus capacity ci that can transmit current traffic among all the links between the nodes of the communication network 100 is less than the total amount of traffic d to be transmitted. The G2 network is created by removing the links forming the traffic path LSP1 from the target. That is, the G2 network indicates a network from which the link forming the LSP1 is removed from the G1 (S404).

Subsequently, a second distance information value dist (i) is obtained for each link i of the network satisfying the G2 based on the current traffic amount y _i and the information on the total traffic amount d to be transmitted. When the yi and d information is used as a variable of a delay function f _i (x _i ) as an example of a cost function for each link, the second distance information value dist (i) is a delay function f _i according to Equation 2 below. Since it is defined as a result of the function f _i '(y _i + d) that differentiates (y _i + d), the corresponding distance information value is obtained by using Equation 2 and y _i and d value information (S405). ).

In Equation 2, each symbol and definition is the same as in Equation 1, except that the target network is G1 in Equation 1 and G2 in Equation 2.

Next, a second end-to-end traffic path (hereinafter referred to as LSP2) is set based on the calculated second distance information value. If LSP2 is found in plural numbers, the calculated second delay function value That is, only one LSP2 is set based on the principle of setting a link having a relatively small second distance information as a traffic path (S406).

Finally, the set first end-to-end traffic path LSP1 is determined as a primary label switching path to allocate the entire traffic to be transmitted, and the set second end-to-end traffic path LSP2 is used as a backup path. Set it to.

On the other hand, in step S404, the G2 network is defined as a network from which only the link forming the LSP1 is removed from the G1 so that the link of the LSP1 and the link of the LSP2 do not overlap each other, but the link and node forming the G2 network from the G1 to the LSP1 You can define this as a network that eliminates them, so that when you compare LSP1 and LSP2, both cross links and nodes do not overlap.

As described in detail above, the traffic routing method for protection switching and / or fast rerouting in a data communication network to which the multi-protocol label switching (MPLS) scheme according to the present invention is applied may be based on a flow amount of traffic to be transmitted. Alternatively, the node cost function (for example, delay function) is calculated, and thus the case in which the generated cost function is a nonlinear delay function is also considered. Thus, the primary LSP and By setting up a backup path, optimized path determination for protection switching and / or fast reroute is possible.

Claims (5)

In a data communication network with a multi-protocol label switching (MPLS) scheme, a label edge router as an egress from a label edge router LER as an ingress and a label switch router LSR as one or more intermediate nodes. A method of establishing an ingress-to-egress traffic path (LSP) to a LER, 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 first 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 a first end-to-end traffic path based on the calculated first distance information value; A fourth step of removing from the object of the link between the node and the node of the communication network the link which constitutes the first end-to-end traffic path and the link whose current capacity for transmitting traffic is less than the total amount of traffic to be transmitted; A fifth step of calculating a second distance information value for each target link remaining as a result of the removal of the fourth 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 sixth step of setting a second end-to-end traffic path based on the calculated second distance information value; And Determining a set first end-to-end traffic path as a primary label switching path to allocate all traffic to be transmitted, and using the set second end-to-end traffic path as a backup path; A traffic routing method for protection switching and / or fast reroute in a data communication network to which a multi-protocol label switching scheme is applied, comprising: a configuration. The method of claim 1, In the second step or the fifth step, a derivative value of the first or second delay function 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. Traffic path setting for protection switching and / or fast reroute in a data communication network to which a multi-protocol label switching method is used, wherein the derivative value of the first or second delay function is used as the first or second distance information value. Way. The method of claim 2, The first and second distance information value, " ", Where i represents the corresponding link (i = 1, ...., m) (m = total 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 transmission A traffic routing method for protection switching and / or fast reroute in a data communication network to which a multi-protocol label switching scheme is applied, wherein the total traffic volume is represented. The method of claim 3, wherein In the third and sixth steps, when there are a plurality of first or second end-to-end traffic paths, a link having a relatively small calculated distance information value is set as a traffic path. A method for traffic routing for fast switching and / or protection switching in a data communication network using a multi-protocol label switching scheme. The method of claim 1, In the fourth step, protection switching and / or fast reroute in a data communication network to which the multi-protocol label switching scheme is further removed, wherein the node forming the first end-to-end traffic path is further removed from the target. How to route traffic for your network.