KR100420659B1 - Method of Multi-casting in the MPLS Network - Google Patents

Abstract

The present invention relates to a multicast method in an MPLS network that enables multicast implementation in a multi-protocol label switching (MPLS) network. The present invention relates to an IP (Internet Protocol) layer in an MPLS control board in an MPLS network. Registering an interface associated with the control channel to the neighbor system as the multicast interface; Identifying a protocol type of an IP packet coming from the non-MPLS network in a label edge router (LER); Forwarding the non-MPLS port registered for multicast in the LER and the MPLS control board when the protocol type is an Internet Group Management Protocol (IGMP) packet; If the protocol type is a multicast data packet, copying and transmitting a multicast channel of a label switching router (LSR) that requires forwarding according to multicast routing information generated by the IGMP packet in the MPLS control board. In this case, multicast data packets can be switched at a high speed in Layer 2, and multicast data packets are not used because the multicast data is copied to the unicast LSP because the multicast data packet transmission does not use the unicast LSP. This avoids waste of resources and eliminates the need for LSPs per multicast group, such as unicast.

Description

Multicasting method in MPLS network {Method of Multi-casting in the MPLS Network}

The present invention relates to a multicast method in an MPLS network, and more particularly, to a multicast method in an MPLS network that enables multicast in an MPLS network.

The increase of Internet users and the change of the type of application service through the Internet have resulted in the increase of Internet traffic, and the increase of the traffic has greatly reduced the quality of the current Internet service. In addition, the diversification of the user's application services has required the high speed of accessing the Internet. Accordingly, various technologies such as high speed modem, ISDN, and cable modem have emerged as solutions of the high speed access technology. In addition to expanding the network, there is a demand for a solution that can solve the scalability of the network including an increase in the number of routers and an increase in the number of router tables.

Therefore, in order to solve the problem of the Internet according to the increase of traffic, it is necessary to expand the bandwidth, that is, to have a high speed packet processing capability, and to speed up the Internet network, to make a gigabit router having a high speed packet processing capability. In order to speed up, the switching technology of the link layer is used.

In other words, when using a switching technology such as ATM, the ATM switching platform is used as a hardware platform for packet delivery. To enable this, a user plane is used to interwork between packet delivery of IP and cell delivery of ATM. And new protocols in the control plane are required.

In addition, a number of new technologies have emerged to improve the transmission capability of traffic, and among them, a technology that can improve the performance of the Internet backbone network by properly combining the layer 2 switching technology and the layer 3 routing technology has come into the spotlight.

However, in order to use these technologies in the Internet backbone network, standardization is required. Accordingly, overall standardization of MPLS technologies is in progress.

An object of the present invention is to enable a multicast implementation in an ATM MPLS network.

In addition, the present invention implements multicast using a multicast connection between the LSR and the LER in an ATM MPLS network, and creates a multicast connection between the LSR and the LER to transmit the multicast data packet to the unicast (Uni-cast). By enabling high-speed switching in Layer 2 without using a Label Switching Path (LSP), the purpose of the present invention is to prevent waste of resources caused by multiple copies of multicast data to a unicast LSP.

In addition, the present invention separates and transmits IGMP (Internet Group Management Protocol) packets and multicast data packets through a control channel between LSR and LER in an ATM MPLS network, thereby enabling multicast group management and multicast routing even within an MPLS network. Therefore, the LSR and the LER selectively transmit only the channel (that is, the connection) that needs forwarding, and its purpose is to provide the same.

1 is a diagram showing the configuration of an Asynchronous Transfer Mode (ATM) multi-protocol label switching (MPLS) network according to an embodiment of the present invention.

2 is a diagram illustrating a configuration for multicast switching according to a multi-cast forwarding route entry in FIG. 1.

3 is a flowchart illustrating a multicast method in an MPLS network according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: ATM MPLS Network 20: System Operator Terminal

31 ~ 34: MPLS Control Board

41: Ingress LER (Label Edge Router)

42: Egress LER 43: LER

50, 51 ~ 54: Label Switching Router (LSR)

In the multicast method in the MPLS network according to an embodiment of the present invention for achieving the above object, the interface associated with the control channel from the MPLS control board in the MPLS network to the neighboring system in the IP layer as a multicast interface Process of doing; Identifying, at the LER, the protocol type of the IP packet coming from the non-MPLS network; If the protocol type is an IGMP packet, forwarding the non-MPLS port registered for multicast in the LER and the MPLS control board; If the protocol type is a multicast data packet, the MPLS control board comprises the step of copying and transmitting to the multicast channel of the LSR required forwarding according to the multicast routing information generated in the IGMP packet do.

Alternatively, the multicast method in the MPLS network according to an embodiment of the present invention further comprises the step of reflecting the multicast routing information generated by the IGMP packet in the MPLS control board to the multicast switching of the layer 2 It is characterized by.

Preferably, the process of reflecting the multicast routing information corresponds to the multicast switching of the multicast channel of the layer 2 in the multicast routing table of the multicast data packet in the multicast routing table of the MPLS control board formed by the exchange of the IGMP packets. Making a step; In the multicast routing table, the multicast channel is checked and included in the output of multicast switching in the case of a multicast channel to a neighboring system registered as the forwarding interface, and is not registered as a multicast route entry. In the case of the multicast channel, the step of excluding from the output of the multicast switching is made. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The configuration of the ATM MPLS network according to an embodiment of the present invention is composed of an ATM MPLS network 10 and a system operator terminal 20, as shown in FIG. 1, and control a plurality of MPLSs in the corresponding ATM MPLS network 10. Boards 31 to 33, Ingress LER 41, Igrez LER 42, and LSR 50, which are largely multicast between the LERs 41 and 42 and LSR 50. To create three connections: multicast switching function to create forwarding engine (FE) functionality with processing at the corresponding Ingres LER (41) and processing at the corresponding Igrez LER (42) and LSR (50). Implement

The system operator terminal 20 generates a multicast connection between the LERs 41 and 42 and the LSR 50 at the command of a system operator, between the LERs 41 and 42 and the LSR 50, or A connection (that is, a channel reserved for multicast) can be created and used between the LSR 50 and another LSR (not shown in the drawing for convenience of description). Here, the connection is used (ie, generated) between subscriber boards of the system, unlike the LDP (Label Distribution Protocol) terminated in the MPLS control boards 31 to 33 and the control Non-MPLS channel for routing. It's a connection. In addition, the control non-MPLS channel is a channel other than the LSP channel in the ATM MPLS network 10, and usually, message packets of LDP or routing protocol are exchanged between the MPLS control boards 31 to 33, and 'RFC1483'. Encapsulation by 'is applied.

The Ingress LER 41 performs functions for IGMP message processing and multicast data processing. The protocol type of an IP packet coming from an non-MPLS network (not shown in the figure for convenience of description) is IGMP (for example, 2), i.e., if the IP packet coming from the non-MPLS network is an IGMP message, the corresponding IGMP message is transmitted to the MPLS control board 31, and the IP packet from the non-MPLS network is an IGMP message. If the destination address is a multicast address, i.e., if the IP packet coming from the non-MPLS network is a multicast data packet, the corresponding multicast data packet is copied to the multicast connection (i.e. channel) of the adjacent LSR 50. In this case, only the LSR 50 that needs forwarding is transmitted according to the multicast routing information.

The MPLS control boards 31 to 33 are boards for controlling each system in the ATM MPLS network 10, that is, the LERs 41 and 42 and the LSR 50, and control IGMP messages between each other. -It transmits through MPLS channel and performs multicast router function.

In the Igrez LER 42 and the LSR 50, when the corresponding system supports multicast and there is a multicast forwarding route entry corresponding to the control channel of the neighboring system, the multicast packet transmitted from the neighboring system receives the corresponding LSR ( It transmits through multicast connection of 50). At this time, if the system does not support multicast or there is no multicast forwarding to the system in the multicast routing table, multicast packet transmission is not necessary. Therefore, the MPLS control boards 31 to 33 of each corresponding system are multicast switching (i.e., multicast) inside the ATM switch (i.e., layer 2) according to the adjacent LSR 50 registered as a forwarding entry of the multicast routing table. Forwarding switching) function. Here, the corresponding multicast forwarding route entry is a network interface corresponding to a branch of the multicast routing tree (that is, an interface acting as a multicast query section) and an interface to its upper multicast router. Among them, the interface into which the multicast packet is introduced is excluded.

In addition, referring to the configuration for multicast switching according to the multicast forwarding route entry, that is, a point-to-multi-point switching scheme, as shown in FIG. 2, the MPLS control board 34 is shown. ), The LER 43 and a plurality of LSRs 51 to 54.

The non-MPLS channels for control from one system, LER 43 or LSRs 51 to 54, to adjacent systems are all terminated at the MPLS control board 34 of each system. In the IP stage, there are independent interfaces associated with control channels to each neighboring system. That is, interfaces associated with control channels from the first LSR 51 to the adjacent system (ie, the LER 43 and the LSRs 52 to 54) are each independently present.

And, the channel for multicast from one system to the adjacent system is defined only between subscriber ports of both systems, and ATM cells transmitted through the multicast channel are either switched in hardware or discarded at layer 2. At this time, the switching of the multicast channel is performed in a point-to-multipoint manner, and in each subscriber board of the ATM switch, merging that transmits cells switched from different input ports to one output channel ( Merging) function. Transmission from the corresponding input (eg, port, VPI, VCI) to the corresponding output (eg, port, VPI, VCI) is called multicast switching.

A multicast method in an MPLS network according to an embodiment of the present invention will be described with reference to the flowchart of FIG. 3.

First, each system in the MPLS network, that is, the MPLS control boards of the LER and LSR, performs the multicast router function. At the IP layer of the MPLS control board, the interface associated with the control channel to the adjacent system is registered as the multicast interface. (Step S1).

Accordingly, an IGMP packet and a multicast data packet are separated and processed. The IGMP packet is transmitted through a control channel in the MPLS network and processed by the MPLS control boards of the LER and LSR. Multicast data packets are hardware switched at Layer 2 within the MPLS network by performing point-to-multipoint switching at the switch stage and merging at the subscriber board.

To this end, the Ingress LER checks the protocol type of the IP header of the IP packet coming from the non-MPLS network (step S2). At this time, it is checked whether the protocol type of the corresponding IP header is IGMP (for example, 2) (step S3).

If the protocol type of the IP header is IGMP, that is, if the IP packet coming from the N-MPLS network is an IGMP message, the IGMP message is transferred to the N-MPLS port registered for multicast and the MPLS control board of each system. It forwards (step S4).

On the other hand, if the protocol type of the IP header is not an IGMP message and the destination address is a multicast address, that is, a multicast data packet except for an IGMP packet, the corresponding multicast data packet is transmitted between the LER and the LSR or the LSR in the MPLS network. A multicast connection (i.e., a channel) between the LSR and the LSR is transmitted. That is, the multicast data packet is hardware-switched at layer 2 in the MPLS network (step S5).

At this time, the switching of the multicast data packet is performed in a point-to-multipoint manner, and each subscriber board of the ATM switch performs a merging function of transmitting cells switched from different input ports to one output channel.

On the other hand, the multicast routing information of the MPLS control board generated by the IGMP message is reflected in the multicast switching of the layer 2, for this purpose, the following operations are performed in the MPLS control board of each system in the MPLS network, that is, the LER and the LSR. Should be done.

First, the multicast routing table of the MPLS control board as shown in FIG. 2 confirms a channel for multicast, wherein a connection for multicast (i.e., a LER and an LSR) to a neighboring system registered as a forwarding interface (i.e., Channel) includes the multicast channel at the output of multicast switching, while a multicast connection (i.e., a channel) to a system that is not registered as a multicast route entry (i.e., LER and LSR). In case of, the channel for multicast is excluded from the output of multicast switching.

In addition, in the layer 3 multicast routing table of the MPLS control board in which the IGMP message is exchanged to a control channel for performing the operation, the forwarding interface of the multicast packet is set to the layer 2 multicast connection (ie, channel). Corresponds to multicast switching.

On the other hand, when the multicast route tree of each system is changed according to the exchange of the corresponding IGMP message by the exchange of the IGMP message between each system, each system checks this to describe the switching configuration of the connection for multicast as described above. It should be changed by the same operation.

As described above, the present invention enables the multicast implementation in the ATM MPLS network, so that the multicast data packet can be switched at a high speed in Layer 2, and the multicast data packet transmission does not use the unicast LSP. This avoids the waste of unnecessary resources caused by multiple copies of cast data to the LSP for unicast, and does not require an LSP per multicast group (i.e. address, subnet) like unicast.

In addition, according to the present invention, since multicast data packet transmission does not use the MPLS control channel, data forwarding speed can be improved without affecting LDP or routing performance.

Claims (5)

Registering an interface associated with a control channel from the MPLS control board in a multi-protocol label switching (MPLS) network to an adjacent system to an IP layer in a multi-protocol label switching (MPLS) network; Identifying a protocol type of an IP packet coming from the non-MPLS network in a label edge router (LER); Forwarding the non-MPLS port registered for multicast in the LER and the MPLS control board when the protocol type is an Internet Group Management Protocol (IGMP) packet; If the protocol type is a multicast data packet, copying and transmitting a multicast channel of a label switching router (LSR) that requires forwarding according to multicast routing information generated by the IGMP packet in the MPLS control board. Multicast method in MPS network, characterized in that made. delete The method of claim 1, And applying the multicast routing information generated by the IGMP packet to the multicast switching of the layer 2 in the MPLS control board. The method of claim 3, The process of reflecting the multicast routing information may correspond to the step of mapping the forwarding interface of the multicast data packet to the multicast switching of the multicast channel of the layer 2 in the multicast routing table of the MPLS control board formed by the exchange of the IGMP packets. ; In the multicast routing table, the multicast channel is checked and included in the output of multicast switching in the case of a multicast channel to a neighboring system registered as the forwarding interface, and is not registered as a multicast route entry. In the case of the multicast channel of the multicast method of the MPS network comprising the step of excluding from the output of the multicast switching. delete