KR20030035590A - Process Method For Transfering Information In Two Layer VPN Based On Multi Protocol Label Switching - Google Patents

Abstract

PURPOSE: An information transmission method in an MPLS(Multi Protocol Label Switching)-based two layers virtual private network is provided to allocate effectively label resources and minimize the amount of information of a VPN(Virtual Private Network), thereby enhancing efficiency of the VPN. CONSTITUTION: Information on the VPN transmitted from an another reception router(PE-A) is inputted from a subscriber reception router(PE-B) and then it is discriminated whether one's own each subscriber's routers belong to the VPN. If one's own each subscriber's routers do not belong to the VPN, the received information is stored in order to use afterwards. If whether one's own each subscriber's routers belong to the VPN, it is discriminated whether an encapsulation type of the subscriber's router is the same as that of a subscriber's router(CE) belong to the VPN. Thereafter, if an encapsulation type of the subscriber's router is not the same as that of a subscriber's router(CE) belong to the VPN, a process is finished.

Description

Process Method For Transfering Information In Two Layer VPN Based On Multi Protocol Label Switching}

The present invention relates to a method for processing information transmission in a multi-protocol label switching (MPLS) -based two-layer virtual private network, and in particular, efficiently allocates the label resources used for communication in the MPLS-based two-layer virtual private network. The present invention relates to a method for improving the efficiency of a virtual private network by minimizing the amount of VPN information that must be transmitted through the network.

In general, in the MPLS-based two-layer virtual private network (VPN), the VPN information is exchanged between the subscriber accepting router (PE) and the subscriber router (CE) can be connected to the desired CE through the PE.

For example, in the configuration of FIG. 1 in which Layer 2 is a frame relay, CE0 and CE2 may use data link connection identifier (DLCI) numbers of 100 to 109, and CE1 and CE3 may use numbers of 200 to 209. Assuming that CE4 can use the numbers 107, 209, 265, 301, 414, 555, 654, 777, and 888, and CE5 can use 417 to 426 as DLCI numbers, PE1 informs PE0 and PE2 about CE1. do.

At this time, the information about CE1 that PE1 should deliver to PE0 is that CE1 belongs to a VPN, and which labels are for connecting to CE0, CE1, and CE2.

The first conventional method for exchanging such VPN information is that PE1 has information about CE1, namely VPN ID, CE ID, CE range (total number of CEs to communicate) and label base, as shown in FIG. To all PEs. In other words, after CE1 consecutively assigns a label value for connecting to another CE, it notifies the label base, which is the lowest value, and the PEs receiving it see the number of CEs belonging to it and add it to the label base by its index. Determined by the label used to communicate with CE1. This method assumes that the labels are assigned continuously, which not only reduces the efficiency of the label resources, but also makes it impossible to run the VPN if the labels cannot be assigned as many times as the number of CEs in the VPN. have.

Another conventional second method for solving this problem is to use several consecutive label pieces as shown in Fig. 2 (b). This is a method of notifying each CE piece of information (VPN ID, CE ID, CE range, CE base, label base). This method has the advantage that it can be used even if the label is discontinuous, but there are some problems.

First, the CE base is needed in addition to the VPN information used in the first method. In other words, since only information about a piece of label required for a CE is conveyed, it is necessary to indicate from which CE the label is to be used. In addition, if the CEs held by the PE correspond to different label pieces, information on each label piece must be passed to the PE. In other words, since many VPN information packets must be transmitted according to the index of CE owned by the PE, since a large portion of the packets are duplicated, the amount of information that needs to be transmitted between PEs is high. . Since this method delivers and processes VPN information for each CE currently owned by each PE, when a label is allocated with a margin, when the CE is added, the label is used by using the previously delivered VPN information without additional delivery of the VPN information. The method of decision cannot be used. Therefore, each time a CE is added, information about the added CE must be delivered to other PEs, and information on other CEs belonging to the same VPN must also be delivered to the added CE, so a lot of VPN information has to be delivered. There is this.

Therefore, the present invention was devised to solve the problems of the prior art, and includes VPN information for a CE in one packet and additionally allocates a label so that additional VPN information packets are not transmitted even when the CE is added. The amount of VPN information that must be delivered through the network while efficiently allocating the label resources used to communicate in the MPLS-based two-layer virtual private network by calculating the label for communicating with each CE using the received VPN information. The purpose of the present invention is to provide a method for improving the efficiency of a virtual private network by minimizing the.

Figure 1 is an exemplary view briefly showing the configuration of a conventional MPLS-based two-layer virtual private network.

2 is an exemplary view illustrating a method of allocating a label resource in FIG.

Figure 3 is an exemplary view briefly showing the format of a conventional FEC element applied.

Figure 4 is an exemplary view showing a simplified format of the FEC element to be applied to the present invention.

5 is an exemplary view illustrating an operation flow of processing VPN information according to the present invention.

6 is an exemplary view illustrating a process of calculating an internal label according to the present invention.

********** Symbol description of the main parts of the drawing **********

10: label for CE0 20: label for CE1

30: Label PE0 to PE2: CE2: Subscriber Router

CE0 ~ CE5: Subscriber Router

In order to achieve the above object, the present invention provides a method of processing information transfer in a multi-layered virtual private network based on multi-protocol label switching (MPLS). Determining whether each subscriber router (CE) belonging to the VPN receives information on the virtual private network (VPN) transferred from the receiving router (PE-A) from the subscriber receiving router (PE-B); If it does not belong to the determination result of the above step, storing the received information for later use, and if belonging to determine whether the CE (corresponding CE) belonging to this VPN is the same as the encapsulation type; If it is not the same, determining whether the VPN information received in the step is information of a corresponding CE; If it is determined in the above step that the information of the CE is terminated, otherwise calculating the inner label (Li) of the packet from the PE-A and the inner label (Lo) of the packet to the PE-A; After calculating the inner labels in said step, determining a data link connection identifier value to be used for communicating with an outer label (Z) to be used for passing the PE-A; The packet from the PE-B (packet for going to PE-A) is set to the route transmitted with the inner label Lo and the outer label Z with the data link connection identifier value determined in the above step, and received with the label Li. The packet is configured to set a route for transmission to the PE-B using the data link connection identifier value, and then activate the data link connection identifier value.

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

In order to deliver VPN information in the label distribution protocol (LDP), the label base is stored in a label type length value (TLV) and the remaining information is stored in a forwarding equivalence rating (FEC) TLV. An example diagram briefly showing the format of an FEC TLV element used to convey FEC TLV. As shown therein, a packet used as shown in the figure includes a type (L2-VPN) and an encapsulation type (ATM PDU). , ATM Cells, Frame Relay, PPP, Cisco-HDLC, Ethernet VLAN, MPLS, etc.), Length (Length), Control Flags (Sequential Forwarding Request, etc.), along with VPN ID, Subscriber Router (CE) ID, The CE range, and the CE base, are included. This CE base contains only one piece of label information from one CE's information, indicating which label piece is from which label for the CE. 4 is a schematic diagram showing the format of the FEC element applied to the present invention. FIG. 4 is a schematic diagram showing the format of the FEC element applied to the present invention. Type, Encapsulation Type, Length, Control Flags, VPN ID, CE ID and CE Interconnect, sub-TLVs, etc., but instead of CE range and CE base Contains information on the number of label pieces and the set of number of CEs each label piece contains.

While FIG. 3 shows information about CE ranges and CE based label pieces, FIG. 4 contains information on all label pieces of a CE since it contains the number of label pieces and the number of CEs for each label piece. Able to know.

The operation of processing the VPN information by a subscriber receiving router (PE) receiving the packet shown in FIG. 4 is shown in FIG. 5.

FIG. 5 is an exemplary view illustrating an operation flow of processing VPN information according to the present invention. As shown in FIG. 5, VPN information (VPN ID = X) for CE having CE ID = m belonging to VPN X transmitted by PE-A is shown. , CE ID = m, number of label pieces = Nm, CE range = {Rm (0), Rm (1),, Rm (Nm-1)}, label base = {Lm (0), Lm (1), , Lm (Nm-1)}) When a PE-B receives a check, it first checks whether the encapsulation method is the same for each CE belonging to VPN X among its own CEs.

The VPN information for the CEs in VPN X is CE ID = k, number of label fragments = Nk, CE range = {Rk (0), Rk (1),, Rk (Nk-1)}, label base = {Lk (0 ), Lk (1),, Lk (Nk-1)}, DLCi list = Dk [m]. If the received VPN information is information about itself (CE-k), the procedure ends.

Otherwise, the label used for going to CE-m and the label used for packets coming from CE-m are calculated as shown in FIG.

6 is an exemplary view illustrating a process of calculating an internal label according to the present invention. As shown in the drawing, first, the CE range is sequentially increased by '1' (i = i + 1) and accumulated (Sm = Sm). + Rm (i)), and it is determined whether the accumulated value Sm reaches a predetermined value k (i value immediately before the accumulated value of Rm (i) becomes larger than k is CE-k at CE). becomes a label fragment index at which a label to be used for a packet going to -m is located), and when the determination result reaches a predetermined value k, it is determined whether the sequentially increased number i is greater than or equal to the number of label fragments Nm. (i> = Nm), if the result is greater than or equal to this determination result, the process is terminated, and if less than, the predetermined value k and the cumulative value Sm are applied to the label base Lm (i) corresponding to the incremented number i. Calculate the value of the internal label Lo by adding the difference (Lo = Lm (i) + (k-Sm)).

In the same manner, it is also possible to calculate the inner label (Li) of the packet from CE-m to CE-k.

Then, as shown in Fig. 5, the inner labels are calculated, and then the DLCi value Dk [m] to be used to communicate with the external label Z and CE-m to be used for passing the PE-A is determined, and CE-k A packet sent from the PE-B to the Dk [m] value (CE-m) is a route for transmitting the inner label with Lo and the outer label with Z, and the packet received with label Li (CE). packet from CE-m to go to -k) sets DLCi Dk [m] to the CE-k route, and then activates the data link connection identifier value.

In FIG. 4, the method according to the present invention seems to increase the size of the packet, but since the number of packets actually transmitted is at most PE, the VPN information transmitted on the network is proportional to the number of CEs belonging to the VPN. It is much reduced compared to the case.

In addition, by over-provisioning and freely assigning labels, each time a CE is added, information about the added CE is communicated to other PEs and information about other CEs is also added to the added CE. More signals can be attenuated because this problem can be solved.

Although the invention has been particularly shown and described with reference to the preferred embodiments, those skilled in the art will appreciate that various modifications are possible without departing from the spirit and scope of the invention. Accordingly, the invention is limited only by the claims.

As described above, in the present invention, a method of processing information transfer in a layer 2 virtual private network based on multi-protocol label switching (MPLS) uses a method of delivering information on all label fragments to each PE so as to deliver VPN information. By doing so, it is possible to supplement the conventional problem of continuously assigning the labels as many as the number of CEs belonging to one VPN, and to solve the conventional problem in which a large amount of VPN information is transmitted.

Claims (3)

In a multi-protocol label switching (MPLS) based two-layer virtual private network, receiving information about a virtual private network (VPN) from another subscriber accepting router (PE-A) received from the subscriber accepting router (PE-B) Determining whether respective subscriber routers (CEs) belong to the VPN; If it does not belong to the determination result of the above step, storing the received information for later use, and if belonging to determine whether the CE (corresponding CE) belonging to this VPN is the same as the encapsulation type; If it is not the same, determining whether the VPN information received in the step is information of a corresponding CE; If it is determined in the above step that the information of the CE is terminated, otherwise calculating the inner label (Li) of the packet from the PE-A and the inner label (Lo) of the packet to the PE-A; After calculating the inner labels in said step, determining a data link connection identifier value to be used for communicating with an outer label (Z) to be used for passing the PE-A; The packet from the PE-B (packet for going to PE-A) is set to the route transmitted with the inner label Lo and the outer label Z with the data link connection identifier value determined in the above step, and received with the label Li. Layer 2 virtual private network based on multi-protocol label switching (MPLS), characterized in that the packet is set as a data link connection identifier value and then a route for transmitting to the PE-B is activated. Information transfer processing in. The method of claim 1, wherein the calculating of the internal labels (Li, Lo) Accumulating the CE range sequentially by incrementing by '1', and determining whether the accumulated value reaches a predetermined value; A second step of determining whether the sequentially increased number is greater than or equal to the number of label fragments when the determination result of the first step reaches a predetermined value; A third step of calculating an internal label (Lo, Li) by adding a difference between a predetermined value and a cumulative value to a label base corresponding to a sequentially increased number when the result is greater than or equal to the determination result of the second step; Information transmission processing method in a multi-protocol label switching (MPLS) based two-layer virtual private network, characterized in that further comprises. The method of claim 1, wherein the VPN information is Type, Encapsulation Type, Length, Control Flags, VPN ID, CE ID and CE Interconnectability, Sub-TLVs, Information transfer in a multi-protocol label switching (MPLS) based two-layer virtual private network, characterized in that it is stored in a forwarding equivalence class (FEC) consisting of the number of label fragments and the aggregate information of the number of CEs included in each label fragment. Treatment method.