KR20050077357A - Method for sorting explict route for cr-ldp in mpls network - Google Patents

Abstract

The present invention is a multiprotocol label switching network (hereinafter referred to as MPLS: Multiprotocol Label Switching) network in the order from the Ingress LER to Egress LER for the explicit path specified by the operator based on the network topology information when using the L-SPP using CR-LDP It relates to a technique for providing an ordered new explicit path.

To this end, the present invention, when an explicit route (ER: Explicit Route) is designated by the operator, generates an explicit route (ER) list for the explicit route (ER), and the manifestation using the cloak topology information The neighboring node is extracted for the node configured in the conventional path (ER) list, and the extracted neighbor node is deleted from the explicit path (ER) list and inserted into the new explicit path (ER) list. By repeating the above process, a new explicit route (ER) list arranged in order from Ingress LER to Egress LER is created and provided to the operator.

Description

Method for sorting explict route for CR-LDP in MPLS network

The present invention relates to an explicit path alignment method of CR-LDP in an MPLS network, and more particularly, to a network topology when an LSP is opened using a CR-LDP in a multiprotocol label switching network (MPLS: Multiprotocol Label Switching) network. It relates to a technology that provides new explicit paths arranged in order from Ingress LER to Egress LER for the explicit path specified by the operator based on the information.

As is known, MPLS is a technical standard standardized by the International Engineering Task Force (IETF), which replaces the existing network layer (Layer 3) packet transmission method with label switching to transmit Internet traffic more efficiently. Next generation Internet router construction technology. MPLS has a feature that can provide services regardless of lower and upper protocol layers. Packet forwarding in MPLS network is done by label exchange, and each node of MPLS network decides the next node to be transmitted by label value included in incoming packet, and exchanges label and transmits MPLS packet to next node. Do this.

MPLS transmits traffic through a Label Edge Router (LER) and a Label Switching Router (LSR). The LER is located at the edge of a network and transmits traffic through interworking between existing network layer packets (IP packets) and MPLS packets. The LSR is located at the center of the network and transmits the packet in the MPLS method.

The label used in MPLS has a size of 20 bits and this value determines the next node to be delivered. The label is predetermined and distributed by the network's signaling protocol (LDP / CR-LDP).

Label Distribution Protocol (LDP) is basically a protocol used to set the Best Effort LSP by referring to a routing path. However, Label Distribution Protocol (LDP) does not support Quality of Service (QoS), but it is currently Asynchronous Tranfer Mode (ATM). It is designated as MPLS standard signaling protocol of high speed national network.

In comparison, a Constraint based LDP (CR-LDP) can set up an LSP that satisfies various constraints, and because constraints can support explicit routes (ERs) or QoS, It is designated as MPLS standard signaling protocol for QoS guarantee of high speed national network based on asynchronous transmission mode.

On the other hand, RSVP-TE (Extentins to RSVP for LSP-Tunnels) performs a similar function to CR-LDP and is widely used in existing router-based MPLS networks.

In general, the LSP should be set up for packet transmission in the MPLS network. The LSP is routed from the ingress LER to the egress LER using a signaling protocol. Representative signaling protocols include LDP / CR-LDP and RSVP-TE. LDP / CR-LDP is used in high-speed national network. LDP protocol is used to configure Best Effort LSP, and CR-LDP is used to set up LSP for QoS support or explicit routing.

LSP is configured using LDP and the packet transmission procedure is as follows.

For each entry in the routing table (configured by the routing protocol), each LER and LSR require a label assignment to the next hop LSR, which receives the request and the LER / LSR performs the label mapping. When the label mapping information is received, the LSP is set up from the Ingress LER through the intermediate LSR to the Egress LER by configuring the Label Information Base (LIB) table. After the LSP is set, IP packets flowing into the network are transmitted through the LSP set according to the destination information of the header.

The procedure for establishing an LSP using the CR-LDP is routed by an explicit path (ER) and the LSP is set to a specified QoS and bandwidth, unlike an LDP in which a path is selected depending on a routing table existing in the MPLS exchange. . The explicit path (ER) is determined by the operator who knows the topology of the entire network and the CRLS-LDP setup is requested to the MPLS exchange.

When the operator opens the LSP using the CR-LDP, if the explicit path (ER) specified by the operator is not aligned in sequence from the Ingress LER to the Egress LER, the Ingress LER to the Egress LER at the actual LSP opening at the MPLS exchange. There is a problem that the path does not exist or the LSP cannot be opened by the path desired by the operator. This problem is a major cause of delay in opening and another problem arises that the operator has to do additional work to verify that the path actually exists and that the order is well aligned from the Ingress LER to the Egress LER.

Accordingly, the present invention has been made to solve the above-mentioned conventional problem, and an object of the present invention is to specify an explicit path ER, in order from the ingress LER to the egress LER. By providing a new explicit path that is ordered by the MPLS exchange, the MPLS exchange can open the LSP with that explicit path (ER).

An explicit path alignment method of CR-LDP in an MPLS network according to the present invention for realizing the above object is specified by an operator in an explicit path (ER) alignment method in an MPLS network using a CR-LDP. Extracting a neighbor node for the ingress LER from the cloak topology information based on the explicit path (ER) list; A second step of determining whether there is a neighbor node belonging to the explicit path (ER) list among the neighbor nodes if the egress LER does not exist among the extracted neighbor nodes; If the neighbor node exists, adding the neighbor node to the new explicit route list and deleting it from the explicit route list; A fourth process of performing the second process and the third process by extracting a neighbor node for the neighbor node from the cloak topology information when a path exists in the explicit route list; And when there is an egress LER among the neighbor nodes extracted in the first process, or the route does not exist in the explicit route (ER) list in the fourth process, the neighbor nodes are arranged in order and stored in the new specification. And a fifth process of preparing an ER list.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail.

1 is a block diagram of an MPLS network to which the present invention is applied.

As shown in FIG. 1, in the MPLS network, there is an LER 11 which performs a function of interworking an IP packet and an MPLS packet at a boundary of a network, and an LSR 12 which performs a function of transmitting only an MPLS packet inside an MPLS network. exist. There is a physical link between MPLS nodes and an MPLS link in which MPLS packets are transmitted in the physical link.

The LER 11 performs packet interworking between the access network and the MPLS network or the Internet and the MPLS network. The access network is composed of DSLAM 22 which performs aggregation function for the xDSL subscriber station 21 and NAS (Network Access System (not shown)), and the Internet is a legacy that routes subscriber traffic to an Internet Service Provider (ISP). It consists of a router (Legacy Router: 31) and the like.

2 is a block diagram of an MPLS network management unit for performing an explicit path alignment method of CR-LDP in an MPLS network according to the present invention.

As shown in the figure, the MPLS network management unit is a cloak topology information storage unit 21, path verification processing unit 22, connection management processing unit 23, connection information storage unit 24, configuration management processing unit 25, And an MPLS exchange interworking unit 26.

The network topology information storage unit 21 stores network shape information such as links and nodes of the MPLS network, and the configuration management processing unit 25 has a function of creating, changing, or deleting nodes or link information of the MPLS network in the GUI. If performed, the function reflects the execution result in the network topology information.

The connection management processing unit 23 performs a function of supporting an operator to set, change, and delete an LSP using a CR-LDP from an Ingress LER to an Egress LER in a GUI, and an explicit path (ER) designated by the operator is When the path verification processing unit 22 designates a new explicit path ER, the MPLS exchange interworking unit 26 performs the CR-LDP setting command and performs the same processing of the LSP change or deletion command.

The path verification processing unit 22 searches for network topology information on the explicit path ER requested from the connection management processing unit 23 and verifies whether the paths are arranged in order from the ingress LER to the egress LER.

The connection information storage unit 24 stores the LSP information of the result when the CR-LDP setting / change / deletion function performed by the connection management processing unit 22 is successful, and the connection information for each MPLS exchange is included here. That is, the interface name, label name, and traffic information into which the label is introduced / exited are stored.

The MPLS exchange interworking unit 26 receives the CR-LDP setting / changing / deleting function from the connection management unit 23, transfers the command to the corresponding MPLS exchange (Ingress LER), and receives the result, and then the connection management unit 23 Performs the function

As shown in FIG. 3, when the path verification request for the explicit path ER is received from the connection management processor 23, the path verification processing unit 22 determines whether the explicit path ER is in the designated state. If an explicit path ER is specified, a list of the current explicit path ER according to the explicit path ER is generated, and the ER processor 31 determines whether the explicit path ER is aligned. An ER receiver 32 for requesting verification; An ER processor 31 for verifying whether the explicit path ER is arranged in order in the network topology from the Ingress LER to the Egress LER through the cloak topology search unit 33; And a cloak topology search unit 33 which searches for a cloak topology for the explicit path and extracts an adjacent node of a specific node at the request of the ER processor 31. The ER processor 31 searches for the shape information of the network through the cloak topology searcher 33, and if the order is not aligned, generates the new explicit path ER based on the network shape information.

Next, an explicit path alignment method of CR-LDP in the MPLS network will be described with reference to the flowchart shown in FIG. 4.

First, when the operator requests the alignment of the explicit path ER through the GUI, the connection management processor 23 requests the explicit path ER to the path verification processor 22 (S2).

By the request, the ER receiving unit 32 of the path verification processing unit 22 determines whether an explicit path ER is designated from the operator (S4), and if an explicit path ER is designated from the operator (S4). Yes in S4) While generating the current ER list based on the specified explicit path (ER) and transmitting it to the ER processing unit 31, the ER processing unit 31 requests the path verification for the ER list (S6). .

The ER processor 31 extracts neighbor node information having a hop count of 1 for the ingress LER from the cloak topology information stored in the cloak topology information storage unit 21 through the cloak topology search unit 33 (S8). If is present (Yes in S10) it is determined whether the egress LER exists among the extracted neighbor nodes (S12). There may be a plurality of neighbor nodes by the neighbor node information extracted in S8.

If the egress LER does not exist (No in S12), it is determined whether there exists a neighbor node belonging to the current explicit route (ER) list among the neighbor nodes (S14), and if the current explicit route (ER) ) If there is a neighbor node belonging to the list (Yes in S14), the neighbor node is added to the new explicit route (ER) list (S16) and the neighbor node is deleted from the current explicit route (ER) list. (S18).

Subsequently, the ER processing unit 31 determines whether the path exists in the current explicit path (ER) list (S20), and if the path exists in the current explicit path (ER) list (Yes in S20), searches for the topology. The neighbor node information having a hop count of 1 is extracted from the cloak topology information stored in the cloak topology information storage unit 21 through the unit 33 (S22).

On the other hand, if the Egress LER is present in the adjacent node in S12 (Yes in S12), or if the path does not exist in the current explicit path (ER) list in S20 (No in S20), it is generated by the process of steps S8 to S18 Create a new explicit path (ER) (S24).

Thereafter, the new explicit path ER is provided to the operator through the connection management processor 23 and the GUI, so that the operator can check the alignment check result for the explicit path ER specified by the operator.

In addition, if an explicit node ER is not specified from the operator as a result of the determination of S4 (No in S4), or an adjacent node is not extracted from the cloak topology information (No in S10), or the determination result of S14. If the neighbor node does not exist in the current explicit path (ER) list (No in S10), the ER processing unit 31 informs the ER receiving unit 32 that an explicit path (ER) does not exist. By outputting the notification, the connection management processing unit 23 and the state that the explicit path (ER) does not exist through the GUI (S26).

By setting the CR-LDP in the MPLS network using an explicit path (ER) in which the order is sorted through the procedure described above, the LSP is set to the path desired by the operator and the failure occurs because the order is not sorted. The operator can efficiently perform operation management in the MPLS network.

According to the present invention as described above, when using the CR-LDP signaling protocol in the MPLS network, since the explicit path can be specified in an aligned state, it is possible to quickly provide the LSP opening, There is an effect that can increase the service satisfaction of.

On the other hand, the present invention is not limited to the above-described embodiment, but can be modified and modified within the scope not departing from the gist of the present invention, such modifications and changes should be regarded as belonging to the following claims. will be.

1 is a block diagram of an MPLS network to which the present invention is applied.

2 is a block diagram of an apparatus to which an explicit path alignment method of CR-LDP is applied in an MPLS network according to the present invention;

3 is a detailed configuration diagram of the path verification processing unit shown in FIG. 2.

4 is a flowchart of an explicit path alignment method of CR-LDP in an MPLS network according to the present invention.

Claims (3)

In explicit path (ER) alignment method in MPLS network using CR-LDP, Extracting a neighbor node for the ingress LER from the cloak topology information based on the explicit path (ER) list designated by the operator; A second step of determining whether there is a neighbor node belonging to the explicit path (ER) list among the neighbor nodes if the egress LER does not exist among the extracted neighbor nodes; If the neighbor node exists, adding the neighbor node to the new explicit route list and deleting it from the explicit route list; A fourth process of performing the second process and the third process by extracting a neighbor node for the neighbor node from the cloak topology information when a path exists in the explicit route list; And If there is an egress LER among the neighbor nodes extracted in the first process, or if there is no route in the explicit route (ER) list in the fourth process, the neighbor nodes are arranged in order and stored in the new explicit. An explicit path alignment method of CR-LDP in an MPLS network, comprising a fifth process of preparing a path (ER) list. The method of claim 1, As a result of extracting the neighbor node in the first process, if there is no neighbor node for the ingress LER, a sixth process of outputting an error message for notifying the operator that there is no explicit path ER is further included. Explicit path alignment method of CR-LDP in the MPLS network, characterized in that the configuration. The method of claim 1, And a seventh process of outputting an error message for notifying the operator that there is no explicit path (ER) if the neighbor node does not exist as a result of the determination of the second process. Explicit path alignment in CR-LDP.