KR100411249B1 - The Label Assignment Method using the BGP table information in MPLS Network - Google Patents

Abstract

The present invention relates to a method for assigning a label using boundary gateway protocol (BGP) table information in a multi-protocol label switch (MPLS) network. The present invention relates to a label assignment method in a multi-protocol label switching (MPLS) network. The method of claim 1, further comprising the steps of: a routing module operating each routing protocol to obtain route information from a neighbor network; A second step of generating a respective routing table for each routing protocol including a border gateway protocol (BGP) using the obtained route information; A third step of scanning each of the generated routing tables to select the best route for each destination; A fourth step of generating a routing information base including next intermediate node information on a destination based on the generated routing table; A fifth step of transmitting the generated routing information base and the boundary gateway protocol (BGP) table information generated in the second step to an MPLS signaling module; Generating, by the signaling module, a label information base based on the received routing information base and BGP table information; And a seventh step of transmitting the generated label information base information to the forwarding table of the label switch.

Description

The label assignment method using the BGP table information in MPLS Network in multiprotocol label switching networks

The present invention relates to a method for allocating a label using Border Gateway Protocol (BGP) table information in a Multi Protocol Label Switch (MPLS) network, and generating an Internet Protocol (IP) routing table. The aggregated next hop information included in the BGP table information by transmitting the information of the BGP table used as the underlying data to the Label Distribution Protocol (LDP) block that manages and assigns the labels. The present invention relates to a label allocation method that can significantly improve the performance of the MPLS network by significantly reducing the consumption of labels and reducing the amount of traffic transmitted between nodes.

Currently, Internet users are growing exponentially, and the user's requirements are the quality of service (QoS) such as voice and video on the Internet in the general data delivery centered on the best-effort service, which is a characteristic of the existing Internet. It is necessary to provide a variety of services that require.

Routers, which are the core equipment of the existing Internet network, execute routing protocols to exchange routing information with each other to make information (routing information) for delivering the packets received to them to the destination. Routing protocols are roughly divided into Routing Information Protocol (RIP), Open Gateway Protocol (OSPF), Interior Gateway Protocol (IGP), and Perimeter Gateway Protocol (BGP). It is divided into External Gateway Protocol (EGP). The internal gateway protocol (IGP) and the external gateway protocol (EGP) are referred to as the internal gateway protocol (IGP), which is operated inside the autonomous system (AS), and the protocol that is operated between the autonomous system (AS) is the external gateway protocol. It is called (EGP). As such, routers on the Internet up to now use the Internal Gateway Protocol (IGP) and the Border Gateway Protocol (BGP) to generate information that reaches the destination of a packet. This is called a routing table and is a tuple in the routing table. This is called a routing entry.

Border Gateway Protocol (BGP) is a common protocol among gateway nodes on the Internet. The routing table contains the addresses that can be accessed (connected) and attributes associated with the route to each node to select the best route. It is. Border Gateway Protocol (BGP) is an IP application protocol that communicates using TCP. When a node detects a change, it sends updated routing information to inform neighboring nodes of its change.

On the other hand, the Internet, which is mainly based on Ethernet, is a technology suitable for general data transfer such as File Transfer Protocol (FTP), and supports multi-protocol label switching (MPLS) to meet user's requirements such as real-time data transfer. Was developed.

MPLS is a protocol between Layers 2 and 3 of a communication protocol. Routers exchange labels between Layers 2 and 3, and write them at the beginning of the packet, and each router forwards the packet's MPLS header information. It is a technology that can deliver a packet at high speed without operating up to three layers by transmitting data by looking at only a label written in the label. That is, MPLS classifies the same Forwarding Equivalence Class (FEC) by using the same destination IP address as a key based on the forwarding table generated by the existing routing protocol, and assigns the same label to routing entries belonging to the same FEC. . By doing this, packets with the same destination will have the same label, which will be delivered at high speed to the destination by label exchange.

In MPLS, this transmission and reception path is established. This is called a Label Switched Path (LSP), which has a connection-oriented characteristic so that Internet traffic can be delivered in real time. In addition, a protocol for exchanging such labels with each other may use BGP or a label distribution protocol (LDP).

The underlying data for label assignment in MPLS is a routing entry created by the routing protocol, which currently has between 100,000 and 200,000 entries on the Internet. That is, when a label is assigned based on so many entries in MPLS, there is a problem that the number of labels increases in proportion to the routing entry.

In other words, in the conventional MPLS network, the information of the routing information protocol (RIP) routing, the shortest path line protocol (OSPF) routing table, and the boundary gateway protocol (BGP) routing table obtained as a result of each routing protocol is applied to the system. It is not stored and is used as the base information for creating an IP routing table. The label for MPLS switching is assigned based on the generated IP routing table. In the case of assigning a label with the information of the IP routing table, the destination address managed by the node is regarded as the forwarding group of the destination address of the IP routing table, and the labels are assigned one by one using the same group, that is, the destination. It takes as many labels as there is information. Therefore, as the Internet network grows, the number of such destinations (routing entries) is increasing exponentially, and thus there is a problem of managing hundreds of thousands of routing entries.

Accordingly, the present invention is to solve the above problems of the prior art, the object of the present invention is to transmit the information of the border gateway protocol (BGP) table to a label distribution protocol (LDP) block that manages and assigns labels In addition, by assigning labels to the aggregated next hop information included in BGP table information, the label consumption is greatly reduced, and the amount of traffic transferred between nodes is reduced, thereby improving the overall performance of the MPLS network. To provide a label assignment method that can be done.

1 is a protocol stack diagram of each node constituting the MPLS network.

2 is a diagram illustrating an example of MPLS network configuration.

3 is an illustration of a border gateway protocol (BGP) table of a label edge router (LER).

4 shows an IP routing table to be stored in a routing information base of a label edge router (LER).

5 shows a label information base of a conventional label edge router (LER).

6 shows a label information base of a label edge router (LER) according to the present invention;

7 is a process flow diagram of a label assignment method using a border gateway protocol (BGP) table in accordance with the present invention;

Explanation of symbols on the main parts of the drawings

101: routing module 102: MPLS signaling module

110: routing information protocol 111: shortest path first protocol

112,115 border gateway protocol 113,117 routing information base

114: Label Distribution Protocol

116: label management and switch control block

In order to achieve the above object, the present invention provides a label assignment method in a multiprotocol label switching (MPLS) network,

A first step of the routing module operating each routing protocol to obtain route information from a neighbor network;

A second step of generating a respective routing table for each routing protocol including a border gateway protocol (BGP) using the obtained route information;

A third step of scanning each of the generated routing tables to select the best route for each destination;

A fourth step of generating a routing information base including next intermediate node information on a destination based on the generated routing table;

A fifth step of transmitting the generated routing information base and the boundary gateway protocol (BGP) table information generated in the second step to an MPLS signaling module;

Generating, by the signaling module, a label information base based on the received routing information base and BGP table information; And

And transmitting the generated label information base information to the forwarding table of the label switch.

In addition, the present invention provides a computer comprising: a first function in which a routing module operates each routing protocol to obtain route information from a neighbor network;

A second function of generating a respective routing table for each routing protocol including a border gateway protocol (BGP) using the obtained route information;

A third function of scanning each generated routing table to select the best route for each destination;

A fourth function of generating a routing information base including next intermediate node information about a destination based on the generated routing table;

A fifth step of transmitting the generated routing information base and the boundary gateway protocol (BGP) table information generated in the second function to an MPLS signaling module;

A sixth function of generating, by the signaling module, a label information base based on the received routing information base and BGP table information; And

A computer readable recording medium having recorded thereon a program for executing the seventh function of transmitting the generated label information base information to a forwarding table of a label switch is provided.

In the present invention, label switch routers (LSRs) on intermediate nodes other than Label Edge Routers (LERs) constituting the MPLS network do not have border gateway protocol (BGP) routing information, thereby enabling efficient label allocation. . The BGP routing table information generated as a result of the BGP routing protocol is external to the autonomous system (AS) because of the inherent characteristics of the BGP, in which the next next hop information is aggregated. The next hop node for the root information of has an interface information outside its own autonomous system (AS).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a typical MPLS protocol stack.

Each MPLS node constituting the MPLS network has a lower physical layer protocol. The MPLS nodes may have physical layer facilities 105 of Asynchronous Transfer Mode (ATM), Frame Relay, Ethernet, and SONET. . The label switch 104 has a forwarding table 118 that can forward packets when a packet is received from the upper module. The label switch 104 also transmits the label switch information to the upper module, and performs a switching function under direct switching control. It also includes a switch control block 119.

The routing module 101 may include a routing information protocol (RIP) 110, a shortest path line protocol (OSPF) 111, a boundary gateway protocol (BGP) 112, and the like, for obtaining routing information between nodes. Routing Information Base (RIB) 113 generated by these routing protocols.

The MPLS signaling module 102 receives a routing information base (RIB) of the routing module, assigns and manages labels to enable label switching, and controls the label switch and the label management and switch control block 116. A label information base (LIB) 117 is generated based on the routing information base (RIB). Also included is a Label Distribution Protocol (LDP) 114 and a Border Gateway Protocol (BGP) block 115 for transmitting and receiving label requests and mapping messages between neighboring nodes.

The IP and TCP / UDP protocols 103 perform a function as a transport protocol of a routing protocol between neighboring nodes, and exist as a protocol stack existing for performing an existing Internet-based communication protocol.

2 shows an example of a general MPLS network configuration.

The entire network is divided into an autonomous system (AS) for the convenience of management and configuration, and in this example, the network is composed of six autonomous systems (AS). Autonomous system (AS) 1234 (201) is an MPLS domain with a network address of 110.10.0.0/16, autonomous system (AS) 2345 (202) is an MPLS domain with a network address of 120.20.0.0/16, and the remaining autonomous Systems (ASs) are also networks with class B network addresses. In other words, there are six MPLS domains. The autonomous system (AS) 1234 network has a network address of 110.10.0.0/16 and has two border routers: label edge router (LER) A 210 and label edge router (LER) B 212. The system (AS) 3456 network 203 is a network having an autonomous system (AS) 2345 (202) as an intermediate network, and the autonomous system (AS) 6789 network 206 is connected to an autonomous system (AS) 4567 (204). The autonomous system (AS) 5678 network 205 is an intermediate network. Label edge routers (LER) A, B, C, D, E, F, G, H nodes in each autonomous system (AS) network are perimeter routers, and have their BP protocols connected to the external network with the BGP protocol. Routing information is transmitted to and received from each other, and the route information is known. Label edge routers (LERs) and label switch routers (LSRs) in each autonomous system (AS) are configured as Routing Information Protocol (RIP), shortest within the autonomous system (AS). While operating an internal gateway protocol (IGP) such as a path priority protocol (OSPF), the label edge routers (LERs) located at the boundary of the autonomous system (AS), exchange route information with each other, as well as the internal gateway protocol (IGP), External Gateway Protocol (EGP), called Border Gateway Protocol (BGP), is used to exchange route information external to its own autonomous system (AS) through border routers (LERs).

Packets received by Label Edge Router (LER) A are forwarded based on routing information held by Label Edge Router (LER) A. Next next hop information in the routing table is forwarded to the next node. It is information. Nodes to which MPLS technology is applied are forwarded to the next node by checking only the label in the label information base generated based on the information in the IP routing table. That is, the packet is forwarded only with the label information of the second layer without checking the header of the IP packet of the third layer.

FIG. 3 illustrates a table of a border gateway protocol (BGP) generated in a label edge router (LER) A in the case of having the network configuration of FIG. 2.

Each Label Edge Router (LER) and Label Switch Router (LSR) constituting MPLS exchanges route information with each other through routing protocol between neighbors. Multiple routing protocols can be operated in one node, and each routing The protocol operation results are created in the table. Figure 3 shows the BGP table that can be obtained as a result of the operation of the BGP routing table of the LER A, the outer edge of the entire network through the label edge router (LER) B, which is the boundary router of the autonomous system (AS) 1234 Route information can be obtained, and the next hop node 302 is generated using the destination 301 as a key as shown in the table of FIG. However, in the conventional scheme, next hop information of the BGP table is not stored in the IP routing table used for the transmission of the actual packet. However, it acquires information of destinations to which the packet should be delivered.

4 illustrates an IP routing table generated based on the BGP table information of FIG. 3.

The IP routing table for actual packet forwarding is generated by combining route information obtained through the internal gateway protocol (IGP) and the external gateway protocol (EGP). In this example, the route information obtained by the BGP table (i.e. Next hop information 402 for the destination information). The next hop information in the IP routing table has the address of the adjacent interface, that is, 110.10.1.1. When packets are received at Label Edge Router (LER) A, the destinations must all be forwarded through the next next hop, which is 110.10.1.1.

FIG. 5 illustrates a conventional label assignment method and illustrates a label information base generated based on the IP routing table of FIG. 4.

The IP routing table of FIG. 4 is transferred to a label distribution protocol (LDP) block of the MPLS signaling module for MPLS label switching, and the LDP block has label information previously transmitted and received between neighboring nodes and its own label information. A label assignment table for the (FEC) 501, i.e., a label information base, is created and stored.

FEC refers to a group of three layer IP packets processed in the same manner (same forwarding process) in a domain composed of MPLS nodes. The mapping of these IP packets to the FEC is performed once at the Label Edge Router (LER), which is an input node entering the MPLS domain. Once the classification of a FEC is determined, the label is bound to that FEC between the upstream label switch router (LSR) and the downstream label switch router (LSR), which are adjacent nodes in the path for that FEC, It is used for label switching of FEC. That is, one FEC is mapped to a label switch path (LSP) from one input node to an output node of an MPLS domain. The FEC is composed of one or more FEC elements, and the FEC may be classified according to an address prefix, that is, destination of routing information. In addition, since labels are assigned for each FEC, the shape of the FEC element has a great influence on the granularity of the label. In the present invention, the label density is increased to reduce the consumption of labels, and as a result, to manage each MPLS node. By reducing the number of labels, it is a way to improve the performance of the system.

In FIG. 5, there is no label value and an interface of the input information because the label edge router LER A functions as an MPLS edge node, and thus the input information does not have a label value. The label information base in the label switch router (LSR) contains information on the input and output sides. Packets with a destination address of 110.10.0.0 are classified as FEC A, and are forwarded to the next node by attaching the label L1 to the IP packet (this is called a label push) via output interface # 2. As in the example of FIG. 5, when a label information base is generated only with information of the existing routing information base, one label L1 to L6 is allocated to each FEC. In this case, you need as many labels as the routing entry (the destination address).

6 shows a label information base when the number of labels according to the present invention is reduced and assigned.

In the conventional method, when a label is allocated based on the IP routing table information of FIG. 4, each label is allocated to each FEC like the label information base of FIG. 5, and a total of six labels are required. In other words, a label is required in proportion to the number of destinations. That is, as many labels as there are FECs are needed.

However, as shown in FIG. 6, when a label is assigned based on the BGP table information of FIG. 3, 120.20.0.0 and 130.30.0.0 (601) allocate the same label L2 603, and 140.40.0.0 and 150.50. .0.0 and 160.60.0.0 (601) also assign the same label L3 (603). Eventually, the number of required labels is three (L1 to L3), and the label assignment is made only as many as the number of interfaces of LER B responsible for connecting to the outside of the autonomous system.

7 is a flowchart illustrating a label assignment method using a BGP table according to the present invention.

Each node of the MPLS operates a routing protocol existing in the routing module to obtain network route information from neighboring nodes. Internal Gateway Protocols (IGPs), such as Routing Information Protocol (RIP) and Shortest Path Line Protocol (OSPF), transmit or receive route information within their own autonomous system (ASP), Through the external gateway protocol (EGP), it is possible to obtain route information outside the own autonomous system (AS) (701). Each node has this route information and, as a result of executing each routing protocol, creates a routing table (702). One result of this is the Border Gateway Protocol (BGP) table of FIG. In addition to the BGP table, a routing information protocol (RIP) table, an OSPF table, and the like are generated (702). The routing tables that result from the execution of each routing protocol are scanned to select the best route for each destination that is route information. For example, in the case of Routing Information Protocol (RIP), select the route with the lowest number of hops, and in the case of OSPF, select the route with the lowest cost of the link as the best route. (703). Create a routing information base as in the example of FIG. 4 used for forwarding packets to a destination. The example of FIG. 4 is a routing information base created by applying only the information of a BGP routing table, and is generated by a routing information base including next hop information on a destination based on a RIP table, an OSPF table, and a BGP table. 704. The routing module in the node transmits this routing information base and the BGP table generated in step 702 to the MPLS signaling module through internal inter-process communication (IPC) (705). The label distribution protocol (LDP) or border gateway protocol (BGP) in the MPLS signaling module generates a label information base as shown in the example of FIG. 6 based on the received information. That is, BGP table information is received and used for label assignment. The conventional method receives only the routing information base and assigns a label for each FEC. When the FEC (address prefix) of the routing information base created with the internal gateway protocol (IGP) and the external gateway protocol (EGP) tables is used as the FEC element. (The destination becomes FEC) is proportional to the routing entry, which means that labels must be assigned as many routing entries. The method according to the present invention uses the BGP table information, which is not stored in the system, for label mapping, and since the BGP table itself has the aggregated information on the external route information, when it is used for label mapping as it is, the consumption of labels is consumed. It is possible to reduce the number of absolutely (706).

The generated label information base information is transmitted to the forwarding table in the label switch which is responsible for forwarding the packet substantially (707), and the received packet is transmitted to the destination through fast switching by label swapping (708). ).

The detailed description and drawings described above have described one embodiment of the present invention, and it will be understood by those skilled in the art that substitution, modification, and the like may be possible.

In the present invention as described above, by assigning a small number of labels using BGP information in the MPLS network, it is possible to efficiently use the resources of the system by reducing the space of the label to be maintained in each node constituting the MPLS, The performance of MPLS nodes (LER and LSR) can be improved by reducing the load on label management and reducing the amount of traffic passing between nodes through Label Distribution Protocol (LDP) and Border Gateway Protocol (BGP).

Claims (4)

In a label assignment method in a multiprotocol label switching (MPLS) network, A first step of the routing module operating each routing protocol to obtain route information from a neighbor network; A second step of generating a respective routing table for each routing protocol including a border gateway protocol (BGP) using the obtained route information; A third step of scanning each of the generated routing tables to select the best route for each destination; A fourth step of generating a routing information base including next intermediate node information on a destination based on the generated routing table; A fifth step of transmitting the generated routing information base and the boundary gateway protocol (BGP) table information generated in the second step to an MPLS signaling module; Generating, by the signaling module, a label information base based on the received routing information base and BGP table information; And And a seventh step of transmitting the generated label information base information to a forwarding table of a label switch. The method of claim 1, The first step is, Internal Gateway Protocols (IGPs), such as Routing Information Protocol (RIP) and Shortest Path Line Protocol (OSPF), transmit or receive route information within their own autonomous system (ASP), Label assignment method characterized in that to obtain the route information outside the autonomous system (AS) through the external gateway protocol (EGP). The method of claim 2, The third step, Scan the routing tables that result from the execution of each routing protocol to select the best route for each destination, which is the route information. In the case of the Routing Information Protocol (RIP), select the route with the least number of hops. In the case of the shortest path narrow line protocol (OSPF), the label assignment method characterized in that the route with the lowest cost is selected as the best route. On the computer, A first function of the routing module operating each routing protocol to obtain route information from a neighbor network; A second function of generating a respective routing table for each routing protocol including a border gateway protocol (BGP) using the obtained route information; A third function of scanning each generated routing table to select the best route for each destination; A fourth function of generating a routing information base including next intermediate node information about a destination based on the generated routing table; A fifth function of transmitting the generated routing information base and the boundary gateway protocol (BGP) table information generated in the second function to an MPLS signaling module; A sixth function of generating, by the signaling module, a label information base based on the received routing information base and BGP table information; And And a program for executing a seventh function for transmitting the generated label information base information to a forwarding table of a label switch.