KR20000060986A - Method for merging of vpi using mpls in the atm system - Google Patents

Abstract

PURPOSE: A virtual path integrating method using a multiprotocol label switching in an ATM(Asynchronous Transfer Mode) system is provided for distributing and allocating a range of a virtual channel recognition value with respect to an input cell in accordance with the length of a label switching path and performing an accurate label mapping operation with respect to a next switching LSR or destination host of each cell without a cell interleaving. CONSTITUTION: A corresponding LSR of an LSR domain computes the length of an LSP(Label Switching Path) with respect to each interface(S210). At this time, the length may correspond to the number of nodes of each LSR of an LSR domain with respect to a path corresponding to each interface. In the corresponding LSR, an end terminal of the LSR domain may be an Egress node or a penultimate node which is a front end of the edge.

Description

A Virtual Path Merging Method Using Multi-Protocol Label Switching in A-T-M System {METHOD FOR MERGING OF VPI USING MPLS IN THE ATM SYSTEM}

The present invention relates to a multi-protocol label switching method, and more particularly, to a virtual path merging method of a label switching router in an A-T-Amp system.

Multiprotocol Label Switching (hereinafter referred to as MPLS) considers up to the IP layer in order to quickly transmit each packet from different source hosts to the corresponding destination hosts. It is a protocol method of switching a label without using it. The MPLS is defined in the Internet Engineering Task Force (IETF). Each switch in the MPLS-supported switching network is called a Label Switching Router (hereinafter referred to as LSR). Each LSR may use a method of merging labels of each packet to reduce the number of labels. This reduces the number of labels managed by each LSR in the MPLS network and enables efficient label management.

On the other hand, when an LSR or an ATM switch that does not perform virtual path merging in an Asynchorous Transfer Mode (ATM) switch network environment supporting MPLS performs label merging, outputs from a plurality of source hosts, respectively. It is virtually impossible for the cells of the packet to be interleaved so that the edge router of the destination host or the corresponding ATM switch can reassemble the interleaved cells.

For example, if a given LSR or ATM switch has different input interfaces of each cell when the virtual path identifier (VPI) and the virtual channel identifier (VCI) of each cell constituting different packets are the same, the given ATM switch may be a cell. The VPI and VCI can be designated according to the Forwarding Information Base (FIB), and the corresponding output interface can be classified and output. However, when the VPI and the VCI of each cell constituting different packets are the same as described above, if the ATM switch that does not support virtual path merging performs label merging, the cells of each packet are interleaved, and the edge of the destination host ( Edge) Routers or ATM switches make cell reassembly impossible.

On the other hand, in an ATM switch network environment, if an ATM switch does not support label merging, a given ATM switch assigns different output interfaces or different labels to cells arriving at different input interfaces or cells having different labels, respectively. . As a result, when a cell of packets having the same Forwarding Equivalence Class (FEC), that is, a destination IP address, arrives with different labels, a predetermined ATM switch allocates different Outgoing Labels and forwards them. That is, when label merging is not used, the number of incoming labels required by each LSR or ATM switch for each FEC is determined by an up-stream node (Forwarding) output by the LSR or ATM switch. Equal to the number of nodes). Therefore, it is difficult for the LSR to determine so many input labels for a particular FEC.

Meanwhile, when an ATM switch performs label merging in an ATM switch network environment, an edge LSR or an ATM switch of a corresponding destination host distinguishes a destination of each cell by a VCI value. Therefore, for proper label merging for packets with the same VPI value, the VCI value, which distinguishes each source, should not collide. Current ATM switches are designed to support VP merging in hardware, but are not specifically implemented in software. In addition, if the ATM switch that performs VP merge does not allocate the output VCI without duplication or collision to distinguish the source or destination for each cell, the correct VP merge cannot be performed.

As described above, when an ATM switch performs label merging in an ATM switch network environment, conventionally, each ATM switch does not support VP merging in software.

In addition, as described above, in the LLS, each LSR may use the same VPI label if the Incoming or Outgoing interfaces are different. Therefore, when the VPI and VCI of each cell constituting the different packets are the same, if the corresponding ATM switch performs VP merging without considering VCI collision, each cell distinguishes not only the VPI but also the destination host. Since the same can be the same, the edge ATM switch before the final destination cannot or cannot distinguish to which destination host each interleaved cell should be sent. This is because the VCI value is used as a criterion for distinguishing cells arriving from different sources because the VCI values may be the same.

Therefore, when an ATM switch performs label merging in an ATM switch network environment, a predetermined range of VCI values for each VPI for an input cell is distributed and allocated according to the length of a label switching path (LSP) of each ATM switch. Should be. As a result, each cell collides during switching, that is, the VCIs of cells corresponding to different packets are not considered to be identical in the edge LSR, so that a proper VP merge is performed.

Accordingly, an object of the present invention is to provide a virtual path merging method in an A-T-M network system supporting multi-protocol label switching.

Another object of the present invention is a virtual channel identifier for a predetermined virtual path identifier for an input cell according to the length of a label switching path of each L-RS in an A-T-M network system supporting multi-protocol label switching. The present invention provides a virtual path merging method for distributing and assigning a range of values, establishing a forwarding information base, and performing a label distribution protocol.

It is still another object of the present invention in an A-T-M network system to support multi-protocol label switching, in which L-S-R calculates the length of a label switching path for each interface and according to the calculated length, a predetermined virtual path. It allocates each virtual channel identifier range for the identifier and distributes it to upstream L-RS-Rs of the corresponding L-RS-R, and distributes the forwarding information base according to the virtual channel identifier range distributed to each L-RS-R. In the case of constructing and performing a label distribution protocol, and subsequently performing a virtual path merging, a predetermined L-AL knows the next switching L-S- of each cell without cell interleaving even if a cell having a label having the same virtual path identifier value is input. The purpose of the present invention is to provide a virtual path merging method capable of performing an accurate label mapping operation on an egg or a target host.

In order to achieve the above objects, the present invention provides a virtual path merging method in an A-T-M network system supporting multi-protocol label switching, and the corresponding L-S-Al calculates the length of the label switching path for each interface. And assigning each virtual channel identifier range for a predetermined virtual path identifier according to the calculated length and distributing them to upstream L-RSs of the corresponding L-RS. A second step of reallocating and distributing the distributed virtual channel identifier range to the upstream L-RSs of each of the distributed L-RSs if the S-Al is not an ingress node; If each of the distributed L-RSs is an ingress node, a forwarding information base is constructed and laid out according to the range of virtual channel identifiers distributed to each of the L-RSs. Characterized by a made of an a third step of performing a distributed protocol.

1 is an example of a label switching router domain illustrating a virtual path merging method of an A-T-M switch according to an embodiment of the present invention in an A-T-M switch network environment.

2 is a flowchart illustrating a virtual path merging method of an A-T-M switch according to an embodiment of the present invention in an A-T-M switch network environment.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific details appear in the following description, which is provided to aid a more general understanding of the present invention, and it should be understood by those skilled in the art that the present invention may be practiced without these specific details. It will be self explanatory. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

FIG. 1 is an example of a label switching router domain illustrating a virtual path merging method of an ATM switch according to an embodiment of the present invention in an ATM switch network environment.

As shown, for convenience of description, four source hosts and four destination hosts are assumed, and the number of LSRs is also assumed to be four. In addition, it is assumed that each LSR has two input / output interfaces. However, a real ATM switch network will consist of multiple hosts, multiple LSRs, and multiple input / output interfaces.

Meanwhile, according to an embodiment of the present invention, the third LSR 140 that is downstream in the path between the source and the target hosts is a VCI for VPI '0' through the first interface to the first LSR 120 that is upstream. Allocate the range (0 to 199). The first LSR 120 divides the VCI range for the VPI '0' into [0 ~ 99] 170 and [100 ~ 199] (172) for each input interface according to its input interface. Reassign The first LSR 120 informs the first source host S1 110 and the second source host S2 112 of the reassigned range. That is, the first LSR 120 allows the first source host S1 110 to use VCI up to [0 to 99] 170 for the VPI '0', and to the second source host S2 112. Instruct the VCI to use [100–199] (172). Similarly for the other paths, the downstream 3rd LSR 140 allocates the VCI range 200 to 399 for the VPI '0' through the second interface to the second LSR 130 that is upstream. The second LSR 130 divides the VCI range for the VPI '0' into [200 to 299] 174 and [300 to 399] 176 for each input interface according to its input interface. Reassign The second LSR 130 informs the third source host S3 114 and the fourth source host S3 116 of the reallocated range. That is, the second LSR 130 allows the third source host S3 114 to use the VCI up to [200 to 299] 174 for the VPI '0', and to the fourth source host S4 116. Instruct the VCI to use [300–399] (176).

In the ATM network environment supporting MPLS as described above, each ATM switch corresponding to the LSR allocates and allocates a range of VCI for each VPI. Each ATM switch establishes an FBI based on the VCI range for each VP that is finally divided, and performs a label mapping operation on an IP address of a corresponding packet with neighbor nodes using a Label Distribution Protocol (LDP). Therefore, even if each ATM switch performs VP merging in the future, it allocates the VCI range for each VPI without conflicting VCI values, so that each ATM switch does not overlap the VCI for a given VPI so that the next node without interleaving. Cell transmission to the host or destination host.

2 is a flowchart illustrating a virtual path merging method of an ATM switch according to an embodiment of the present invention in an ATM switch network environment. A description with reference to FIG. 1 is as follows.

In step 210, the corresponding LSR on the LSR domain calculates a length of a label switching path (LSP) for each interface. In this case, the length may be the number of nodes of each LSR on the LSR domain for the path corresponding to each interface. In addition, the corresponding LSR may be a Penultimate node whose end on the LSR domain is an Egress node or a front end of the edge. In this case, when the penultimate node performs step 210, the penultimate node is to reduce the computation load of the egress node.

In step 220, the corresponding LSR allocates a VCI range according to the LSP length. For example, if the length is long, the VCI range is largely allocated. If the length is small, the VCI range is small. In step 230, the corresponding LSR distributes the VCI range to each upstream LSR through each interface. In step 240, it is checked whether each LSR distributed the VCI range is an ingress node which is a start node on a domain. In this case, the inspection operation may be performed by the distributed LSR itself. As a result of the inspection, in step 250, each of the distributed LSRs reassigns the VCI range to each upstream LSRs through its interface. The control operation from step 230 is performed again. On the other hand, if the check result of step 240 is the ingress node, in step 260, each LSR on the domain constructs an FIB and performs LDP along each distributed VCI range. In this case, performing LDP includes a label mapping operation for an IP address of a corresponding packet with neighboring LSRs.

In addition, due to the virtual path merging method of the ATM switch according to the embodiment of FIG. 2, when performing VP merging in the future, a predetermined LSR has a label VCI value of each cell even if a cell having the same label has the same VPI value. Since they are all different, it can be seen that an accurate label mapping operation for the next switching LSR or destination host of each cell can be performed without cell interleaving.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

In the A-T-M network system supporting multi-protocol label switching as described above, the virtual path merging method according to an embodiment of the present invention is for L-S-Al to calculate the length of the label switching path for each interface. According to the calculated length, each virtual channel identifier range for a predetermined virtual path identifier is allocated and distributed to upstream L-RSs of the corresponding LS, and the virtual channel to which each RS is distributed. In case of performing virtual path merging by constructing forwarding information base and label distributing protocol according to the range of identifiers, a certain RS-Al is used for each cell even if a cell having the same label has the same virtual path identifier value. Because the label virtual channel identifier values are all different, the next switching LS-AL or destination hose of each cell without cell interleaving The exact label mapping operation for which a number of benefits that can perform.

Claims (3)

In a virtual path merging method in an A-T-M network system supporting multi-protocol label switching, The LS-AL calculates the length of the label switching path for each interface and allocates each virtual channel identifier range for a given virtual path identifier according to the calculated length and upstream of the corresponding LS-AL. The first step of distributing to L-S-Als, Reallocating and distributing the distributed virtual channel identifier range to the upstream L-RSs of each of the distributed L-RSs if the distributed L-RSs are not ingress nodes; , A third step of establishing a forwarding information base and performing a label distribution protocol according to the range of virtual channel identifiers distributed to each L-LS-AL if the distributed L-RS is an ingress node; Virtual path merging method characterized in that consisting of. The method of claim 1, wherein performing the label distribution protocol of each L-LS of the third step, Virtual path merging method characterized in that it includes a label mapping operation of the Internet protocol address of the packet with the neighbor L-S-Al. The method according to claim 2, wherein the corresponding L-S-R of the first step, Virtual path merging method characterized in that the egress node and penalty mate node.