KR100776790B1 - Message processing method of LSR for setting LSP using the RSP-TP protocol - Google Patents

Abstract

The present invention relates to a message processing method in an LSR of MPLS (Multiprotocol Label Switching), and to set an LSP using a Resource Reservation Protocol-Traffic Engineering (RSVP-TE) protocol to reduce a failure rate of a label switched path (LSP) setting. A method of processing a message of a label switching router (LSR), wherein when a corresponding LSR receives a message, it is determined whether the received message is a forward message sequentially delivered on an LSP, and the received message is not a forward message. The method may include collecting available bandwidth information currently available on a link between the corresponding LSR and the previous LSR on the LSP, and then transmitting the received LSR with the received message to the previous LSR.

Description

 Message processing method and Apparatus in LSR for setting LSP using RSVP-TE protocol}

1 is a flowchart illustrating a LSP setting method using a conventional PSVP-TE;

2 is a flowchart illustrating a configuration for schematically explaining a process of performing an LSP setting method using a PSVP-TE according to an embodiment of the present invention;

3 is a flowchart illustrating a configuration for schematically explaining a processing process when an LSP setting using a PSVP-TE fails according to another embodiment of the present invention;

4 is a flowchart illustrating a configuration for schematically describing a processing procedure when an LSP set using PSVP-TE fails according to another embodiment of the present invention; and

5 is a flowchart illustrating a configuration for schematically explaining an operation process of an LSR for configuring an LSP using a PSVP-TE according to another embodiment of the present invention.

The present invention relates to a message processing method in the LSR of the MPLS, and to a message processing method of the LSR for configuring the LSP using the RSVP-TE protocol in order to reduce the failure rate of the LSP path establishment.

Multiprotocol Label Switching (MPLS) is a proven, standard technique for speeding up and managing network traffic flows. It is involved in establishing a specific path for a given packet sequence, with a label within each packet to allow LSRs. (Label Switching Router) can save time to see the address of the node to forward the packet.

Protocols that can use a Label Switched Path (LSP) configuration in consideration of traffic engineering in such an MPLS-based network include a Constraint-based Routed Label Distributed Protocol (CR-LDP) and Resource Reservation Protocol-Traffic Engineering (RSVP-TE). . Among them, CR-LDP is a protocol that does not require a separate mechanism to ensure the continuity of the LSP, the technology using the CR-LDP has a weak point in terms of high availability, there is also a problem in terms of fault tolerance of the LSP.

The RSVP-TE is an extended protocol by applying a refresh rate reduction technique. Since the RSVP-TE protocol has a soft state, the RSVP-TE protocol basically has a soft state of a path state block and a reservation state block. In order to maintain integrity, the refresh must be continuously performed. The refresh message is sent using a pass message and a retention message for each LSP.

1 is a flowchart illustrating a LSP setting method using a conventional PSVP-TE. Referring to FIG. 1, an access network includes LSRs 1 through 5 (102 through 106) of various paths between an entrance LSR 101, which is an entry point into an MPLS network, and an exit LSR 107, which is an exit point. At this time, when the LSP is initially established through the exchange of messages by the RSVP-TE between the inlet LSR 101 and the outlet LSR 107, IP packets arriving thereafter are intermediate with the inlet LSR 101 through the already established LSP. It passes through the LSR3 104 and the LSR4 105 to the exit LSR 107.

At this time, in the LSP setting process, the inlet LSR 101 first decides to set a new LSP to the outlet LSR 107. In consideration of the traffic parameters, the entrance LSR 101 determines that the IP packet should be delivered to the exit LSR 107 through the LSR3 104 and the LSR4 105.

In addition, a path message including a traffic parameter for a new LSR is generated, and the message is transmitted to the LSR3 104 by being loaded on the IP datagram. At this time, in the IP datagram transmitted to the LSR3 104, path information about the LSR3 104, the LSR4 105, and the exit LSR 107 is set.

The LSR3 104 receiving the IP datagram transmits the message to the next path LSR4105 according to the path specified in the message, and the LSR4 105 transmits the corresponding IP datagram message to the exit LSR 107.

Then, the exit LSR 107 reserves the necessary resources by the traffic parameters included in the corresponding IP datagram message. In addition, the exit LSR 107 selects a label for the reserved new LSP, and transmits this label to the LSR4 105 through a retention message (Resv message), which is a response message. At this time, the Resv message includes detailed information on the reservation required for the LSP.

Upon receiving this Resv message, the LSR4 105 transmits the message to the LSR3 104, and the LSR3 104 also forwards the Resv message to the inlet LSR 101 as in the LSR4 103.

Since the inlet LSR 101 is an inlet for the newly created LSP, it does not add a new level, but forwards it to the upstream LSR.

In this case, when the LSP is set in the MPLS-based network using the RSVP-TE protocol according to the prior art, the failure rate of the LSP setting is high because only the success of the setting is determined based on the message transmitted to the inlet LSR. There is this.

The first object of the present invention for solving the above problems, provides a method that can reduce the set failure rate when calculating the Label Switched Path (LSP) path using the Resource Reservation Protocol-Traffic Engineering (PSVP-TE) protocol It is.

It is a second object of the present invention to provide a method for reducing the risk that an LSP configuration may fail due to inaccuracy of network state information when establishing an LSP for traffic engineering in a multiprotocol label switching (MPLS) network.

In order to achieve the object of the present invention as described above, a message processing method of a label switching router (LSR) in a multiprotocol label switching (MPLS) based network using Resource Reservation Protocol-Traffic Engineering (RSVP-TE) according to the present invention ,

A first step in which the first LSR receives the message;

A second step of checking whether the received message is a path message delivered from a second LSR that is a previous LSR of the first LSR on a label switched path (LSP) including the first LSR; And,

If the received message is not a path message as a result of the checking of the second step, the available bandwidth information currently available on the link between the first LSR and the second LSR is collected, and then the message received in the first step. And a third step of transmitting to the second LSR.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing in detail the operating principle of the preferred embodiment of the present invention, if it is determined that the detailed description of the related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In addition, the same reference numerals are used for parts having similar functions and functions throughout the drawings.

FIG. 2 is a flowchart illustrating a configuration for schematically explaining a process of performing a LSP setting method using a PSVP-TE according to an exemplary embodiment of the present invention. Of course, the above process may include other configuration in addition to the above-described configuration, Figure 2 shows only the configuration necessary for convenience of description.

Referring to FIG. 2, first, LSR A 100, which is the inlet LSR, decides to establish a new LSP to LSR D 400, which is the outlet LSR. At this time, in consideration of the traffic parameters in the access network illustrated in FIG. 2, the LSR A 100 determines the LSP that delivers the IP packet to the LSR D 400 through the LSR B 200 and the LSR C 300. .

Next, a path message containing the traffic parameters for the new LSR is generated, and the message is loaded on the IP datagram and transmitted to the LSR B 200, which is the next LSR in the forward direction, on the LSP. In the path message, path information of the LSR B 200, the LSR C 300, and the LSR D 400 is set.

Upon receiving the IP datagram from the LSR A 100, the LSR B 200 determines whether the LSR B 200 is an exit LSR for the corresponding LSP based on the route message. In this case, as shown in FIG. 2, since the LSR B 200 is not an exit LSR for the corresponding LSP, the LSR B 200 refers to a path message included in the IP datagram, and according to the path specified in the message, the next LSR of the forward path. Forward the IP datagram. That is, as shown in FIG. 2, the IP datagram is transmitted to the LSR C 300 which is the next path of the LSP according to the path message included in the IP datagram.

Similarly, the LSR C 300 also checks whether it is an exit LSR based on the route message. As shown in FIG. 2, since the LSR C 300 is not an exit LSR for the corresponding LSP, the LSR C 300 transmits the IP datagram to the LSR D 400, which is the next LSR on the LSP.

The LSR D 400 identifies itself as an exit LSR based on a route message included in the corresponding IP datagram. Next, LSR D 400, the exit LSR of the LSP, creates a Reservation message (Resv message) containing detailed information about the reservation required for the LSP, and then, is the previous LSR of the LSR D 400 on the LSP. The bandwidth information <AB ₃ > currently available on the link between the LSR C 300 and the LSR D 400 is transmitted to the LSR C 300.

Receiving such a Resv message, LSR C (300), <AB which is the bandwidth information currently available on the link between the LSR B (200) and the LSR C (300), the previous LSR of the LSR C (300) on the LSP. ₂ > is transmitted to the LSR B (200), the previous LSR on the LSP, along with the Resv message, <AB ₂ , AB ₃ >, which is missing bandwidth information plus <AB ₃ >, which is the bandwidth information received from the LSR D (400). do.

The LSR B 200 operates in the same manner as the LSR C 300, and is currently available in the link between the LSR A 100 and the LSR B 200, which are the previous LSRs of the LSR B 200 on the LSP. wherein the bandwidth information of <AB _1> the LSR C the received bandwidth information transmitted from the _{(300) <AB 2, AB} 3> cumulative bandwidth information of _{<AB 1, AB 2, AB} 3> added to with the Resv message Transmit to LSR A (100), the previous LSR on the LSP.

As the latest bandwidth information, the LSR A (100), which is an entrance LSR that receives the accumulated bandwidth information <AB ₁ , AB ₂ , AB ₃ >, is reflected in the link state information table and used to calculate the next path.

3 is a flowchart illustrating a configuration for schematically describing a processing process when an LSP setting using a PSVP-TE fails according to another embodiment of the present invention. Of course, the above process may include other configuration in addition to the above-described configuration, Figure 3 shows only the configuration necessary for convenience of description.

Referring to FIG. 3, first, the LSR A 100, which is the inlet LSR, decides to make a new LSP setting up to the LSR D 400. At this time, in consideration of the traffic parameters in the access network illustrated in FIG. 3, the LSR A 100 delivers an IP packet to the LSR D 400, which is an exit LSR, through the LSR B 200 and the LSR C 300. Determine.

Next, a path message containing the traffic parameters for the new LSR is generated, and the message is loaded on the IP datagram and transmitted to the LSR B 200, which is the next LSR in the forward direction, on the LSP. In the path message, path information of the LSR B 200, the LSR C 300, and the LSR D 400 is set.

Upon receiving the IP datagram from the LSR A 100, the LSR B 200 determines whether the LSR B 200 is an exit LSR for the corresponding LSP based on the route message. In this case, as shown in FIG. 3, since the LSR B 200 is not an exit LSR for the corresponding LSP, the LSR B 200 refers to a path message included in the IP datagram, and according to the path specified in the message, the next LSR of the forward path. Forward the IP datagram. That is, as shown in FIG. 3, the IP datagram is transmitted to the LSR C 300 which is the next path of the LSP according to the path message.

Similarly, LSR C 300 also checks whether it is an exit LSR based on the route message. As shown in FIG. 3, since the LSR C 300 is not an exit LSR for the corresponding LSP, the LSR C 300 transmits the IP datagram to the LSR D 400 which is the next LSR on the LSP.

At this time, as shown in FIG. 3, the link between the LSR D 400, which is the next LSR of the LSR C 300, is blocked on the LSP. This blocking occurs due to lack of bandwidth or link down in the links between LSRs.

Next, the LSR C 300 creates an error message (PathErr message) including information indicating that the path message cannot be transmitted, and inserts location information (LocID information) of the LSR or link where blocking has occurred in the PathErr message. Next, <AB ₂ >, which is bandwidth information currently available on the link between the LSR C 300 and the LSR B 200, is transmitted to the LSR B 200, which is a previous LSR on the LSP.

The LSR B 200 is <AB ₂ >, which is bandwidth information received from the LSR C 300, and <AB which is bandwidth information currently available on the link between the LSR B 200 and the LSR A 100. Bandwidth information <AB ₁ , AB ₂ > plus ₁ > is transmitted to the LSR A 100, which is a previous LSR on the LSP, with the PathErr message.

The LSR A 100 receiving the LocID and the latest bandwidth information <AB ₁ , AB ₂ > is used to calculate the next path by reflecting the information in the link state information table.

4 is a flowchart illustrating a configuration schematically illustrating a processing process when an LSP set using a PSVP-TE fails according to another embodiment of the present invention. Of course, the above process may include other configuration in addition to the above-described configuration, Figure 4 shows only the configuration necessary for convenience of description.

Referring to FIG. 4, LSR A 100, LSR B 200, LSR C 300, and LSR D 400 are set as LSPs for delivering an IP packet.

First, the LSR D (400) checks whether the LSP set above is no longer required to be maintained, and if it is determined that it is no longer necessary, the LSR D (400) creates an LSP failure message (ResvTear message) based on this information, and then the ResvTear message. And <AB ₃ >, bandwidth information currently available on the link between the LSR D 400 and the LSR C 300, to the LSR C 300, the previous LSR on the LSP.

Receiving such a ResvTear message, LSR C (300), <AB which is the bandwidth information currently available on the link between the LSR B (200), which is the previous LSR of the LSR C (300) and the LSR C (300) on the LSP. ₂ > together with the ResvTear message to LSR B 200, the previous LSR on the LSP.

The LSR B 200 operates in the same manner as the LSR C 300, and is currently available in the link between the LSR A 100 and the LSR B 200, which is the previous LSR of the LSR B 200, on the LSP. to which bandwidth information is <AB _1> the LSR C (300) received bandwidth information of <AB _2> accumulated bandwidth information of <AB _1, AB _2> obtained by adding the transmission from with the ResvTear message is earlier LSR on the LSP Transmit to LSR A (100).

As the latest bandwidth information, the LSR A (100), which is an entrance LSR that receives the accumulated bandwidth information <AB ₁ and AB ₂ >, is used to calculate the next path by reflecting the information in the link state information table.

5 is a flowchart illustrating a configuration for schematically describing an operation of an LSR for configuring an LSP using a PSVP-TE according to another embodiment of the present invention. Of course, the above process may include other configuration in addition to the above-described configuration, Figure 5 shows only the configuration necessary for convenience of description.

Referring to FIG. 5, first, the LSR (hereinafter referred to as 'first LSR') receives a message from an external LSR (S400).

Next, it is checked whether the received message is a route message forwarded (S410). In the case of the message path message, the message is created at an inlet LSR on the LSP determined including the first LSR, and is located from an LSR located immediately before the first LSR on the LSP (hereinafter, referred to as a 'second LSR'). It was delivered.

If it is determined in step S410 that the message is not a route message, the available bandwidth information is collected (S411), and then the message received in step S400 and the information collected in step S411 to the previous LSR on the LSP. Transmit (S412). Among the messages received by the first LSR, a message which is not a path message, is a response message (Resv message) created at the exit LSR of the LSP and transmitted to the inlet LSR as a response to the path message, and during the path message transmission. An error message (PathErr message) that is created at the immediately preceding LSR of the blocked link and sent to the inlet LSR when some links are blocked, or a failure notification message (ResvTear) that is created at the exit LSR and sent to the inlet LSR when the set LSP fails Message).

The available bandwidth information in step S411 means bandwidth information currently available on the link between the first LSR and the second LSR.

If it is determined in step S410 that the message is a route message, it is determined whether the first LSR is an exit LSR for the LSP of the route message included in the message (S420).

If it is determined in step S420 that the first LSR is the exit LSR, a Resv message is created (S421), and then available bandwidth information, which is bandwidth information currently available on a link between the first LSR and the second LSR, is collected. Next, in step S411, the Resv message created in step S421 and the information collected in step S411 are transmitted to the second LSR (S412).

If it is determined in step S420 that the first LSR is not the exit LSR, the LSR immediately after the first LSR on the next path on the LSP, that is, the LSP including the first LSR (hereinafter, referred to as a “third LSR”). Check whether the blocking occurs due to lack of bandwidth or link down in the link between the (S430).

If it is determined in step S430 that blocking has occurred, a PathErr message is created (S431), and then available bandwidth information which is currently available bandwidth information on the link between the first LSR and the second LSR is collected (S411). The Resv message created in step S421 and the information collected in step S411 are transmitted to the second LSR (S412). At this time, in the preferred embodiment applicable to the present invention, the PathErr message generated in step S431 may preferably include LSR or link location information where blocking has occurred.

If it is determined in step S430 that no blocking has occurred, the message received in step S400 is transmitted to the third LSR.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those skilled in the art.

According to the present invention, it is possible to reduce the risk that the LSP configuration may fail due to inaccuracy of network state information when establishing the LSP for traffic engineering in the MPLS network.

In addition, according to the present invention, LSP path setting by calculating the LSP path using the location information of the failure in the message delivered to the LSR A (100) using the PSVP-TE protocol or the available bandwidth information of the links through the message. The failure rate can be reduced.

Claims (7)

In a network based on Multiprotocol Label Switching (MPLS) using RSVP-TE (Resource Reservation Protocol-Traffic Engineering), A first step of receiving a message by a first label switching router (LSR); A second step of confirming whether the received message is a forward message delivered from a second LSR that is a previous LSR of the first LSR on a label switched path (LSP) including the first LSR; And, If the received message is not the forward message as a result of the checking of the second step, the available bandwidth information currently available on the link between the first LSR and the second LSR is collected, and then the message received in the first step. And a third step of transmitting to the second LSR. The method of claim 1, A fourth step of confirming whether the first LSR is an exit LSR for the LSP of the path message included in the received message when the received message is a forward message as a result of the checking of the second step; And, If it is determined that the first LSR is the exit LSR, the fourth step may further include a fifth step of creating a response message to the forward message and transmitting the response message to the second LSR. How LSRs handle messages. The method of claim 2, When the response message is transmitted to the second LSR in the fifth step, the bandwidth information currently available on the link between the first LSR and the second LSR is also transmitted. The method of claim 2, If it is determined that the first LSR is not an exit LSR as a result of the checking of the fourth step, checking whether blocking occurs due to lack of bandwidth or link down on the next path on the LSP; And, If it is determined that the blocking has occurred as a result of the sixth step, the LSR further comprises a seventh step of creating an error message indicating that an error has occurred on the path and transmitting it to the second LSR. How messages are processed. The method of claim 4, wherein When transmitting the error message to the second LSR in the seventh step, the message processing method of the LSR characterized in that it also transmits the bandwidth information currently available on the link between the first LSR and the second LSR. The method according to claim 4 or 5, The error message generated in the seventh step includes the LSR or the location information of the link in which the blocking occurs, LSR message processing method. The method of claim 4, wherein If it is determined that blocking has not occurred as a result of the checking of the sixth step, transmitting the message received in the first step to the third LSR, which is the next LSR of the first LSR, on the LSP including the first LSR. Characteristic processing method of LSR. .

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