CN101656663B - A method, device and system for forwarding MPLS multicast messages - Google Patents

Abstract

The invention discloses a method for forwarding a MPLS multicast message, which comprises the steps of: receiving a message transmitted by at least two upstream nodes, wherein the message comprises label information and address information of the upstream nodes, and the label information is distributed by the upstream nodes; determining label spaces according to the address information of the received message, and searching a forwarding list in the label spaces; acquiring message forwarding information from the forwarding list according to the label information; and transmitting the message according to the message forwarding information. The invention also provides a corresponding forwarding device and a corresponding forwarding system. The method, the device and the system can solve the problems of multicast upstream label distribution and neighboring label space identification of MPLS; an expandable method for forwarding the MPLS multicast message is provided by fully using bearing layer information; and the processing complexity of equipment can be effectively reduced.

Description

A method, device and system for forwarding MPLS multicast messages

technical field

The invention relates to the field of communication technology, in particular to a forwarding method, device and system for MPLS multicast messages.

Background technique

Multi-Protocol Label Switching (MPLS, Multi-Protocol Label Switching) is a label switching technology for Layer 3 switching. It can use tags to guide high-speed and efficient data transmission on an open communication network, introduce a connection mode into a connectionless network, reduce network complexity, and be compatible with various existing mainstream network technologies. Multi-protocol label forwarding MPLS is used on any link protocol, which can carry data of any protocol, provide high-quality QoS guarantee, support larger-scale network applications, and replace the protocol carrier of IP addressing and forwarding. It usually works above the link layer protocol and under the network layer IP protocol.

The MPLS protocol can also nest and carry itself to form a label stack. In actual networking applications, there are two or three layers of label nesting, and virtual private network (VPN, Virtual Private Network) tunneling technology is generally used. In theory, tags can be nested infinitely to support more business applications and extensions.

If: the MPLS packet is sent by a label switching router (LSR, Label Switch Router) R1 to another label switching router LSR R2. If labels are distributed by R2, it is called "downstream label assignment", and if labels are distributed by R1, it is called "upstream label assignment".

When transmitting MPLS multicast data in point-to-multipoint (P2MP, Point-to-Multipoint), multipoint-to-multipoint (MP2MP, Multipoint-to-Multipoint) links or tunnels, it is necessary to use the "upstream label allocation" mode. To make use of the "replication" capability of P2MP, MP2MP links or tunnels; this requires the use of "neighbor label space", which is used to store labels of adjacent routers and storage space for corresponding routing information. The forwarding plane needs to determine the "label space" where the label stack is located according to the information carried in the MPLS multicast (MC, Multicast) message, so as to further process the label stack. Therefore, when MPLS multicast data adopts upstream label allocation, what is the structure of the MPLS label stack and how to determine the "neighbor label space".

A kind of technical scheme that prior art provides is as follows:

For example, when Ethernet carries MPLS services, the protocol type Ether type0x8847 is used to indicate that Ethernet unicast carries MPLS unicast packets. Of course, it can also be used to indicate that Ethernet frames carry MPLS multicast packets, but it cannot indicate that labels are distributed by upstream nodes. Ethernet MPLS multicast packets. The protocol type Ether type0x8848 is used to represent the Ethernet MPLS multicast message distributed by the upstream node.

It is mentioned in the draft-ietf-mpls-multicast-encaps-10.txt protocol that when an LSR sends an MPLS multicast message in a multicast Ethernet frame, the destination MAC address of the Ethernet message must be set to 01-00 -5e-8v-wx-yz, where vwxyz (v, w, x, y, z is a hexadecimal number, each of which is 4 bits, a total of 20 bits) can be set to "0" or in the MPLS label stack tag value;

If vwxyz is set to "0" and the label value L0 (namely Label0) is the same, as shown in Figure 1, the LSR at the receiving end cannot determine which LSR the message comes from at the sending end.

If, vwxyz is set as the label value in the MPLS label stack, then the MPLS label stack may contain 2 or more layers of MPLS labels, then the default setting vwxyz is the second layer label value. If the MPLS label stack has only one layer of labels, then vwxyz is set to the value of the first layer of labels.

The MPLS multicast service data is carried over the Ethernet, and the label value L0 is used to distinguish the MPLS multicast "neighbor label space".

As shown in Figure 1, when MPLS OVER ETH is based on Ethernet, R1 (network device, such as LSR) establishes an LSP1 through the Layer II network and R3; R2 establishes an LSP through the Layer II network and R3 One LSP2. The two LSPs distribute labels based on upstream nodes R1 and R2 respectively.

R1 copies the second-layer label L1 to the vwxyz (20bit) of the destination MAC address (DMA, Destination MAC Address); R2 copies the second-layer label L1 to the vwxyz (20bit) of the destination MAC address DMA. Since the destination MAC addresses of R1 to R3 and R2 to R3 are all R3, the content of L1 is the same, so it depends on the difference of L0 to distinguish which node it comes from. When R3 receives two messages, it distinguishes the "neighbor label space" through L0, so as to judge whether the message comes from R1 node or R2 node.

In this scheme, the label distribution of R1 node and R2 node is uncertain, so L0 is not unique; if the first-layer label distributed by R1 node and the first-layer label value distributed by R2 node are the same, for example, both are L0, Then R3 cannot distinguish the "neighbor label space", that is, two different "neighbor label spaces" cannot be mapped through the first-layer label value Label, and R3 cannot determine whether the packet comes from the R1 node or the R2 node. This will cause the packets sent by the R1 node and the packets sent by the R2 node to be forwarded by the R3 node only on one path. If the forwarding path of the message sent by the R1 node and the message sent by the R2 node to the R3 node is different, then the R3 node forwards it incorrectly, thereby increasing L0 to identify neighbor label space and waste resources.

Another technical scheme in the prior art is as follows:

In an IP tunnel, if the destination IP address is a multicast address, the IP tunnel is a point-to-multipoint tunnel or a multipoint-to-multipoint tunnel. At this time, the 20 bits of L0 are used as the mapping information of the "neighbor label space".

IP carries MPLS multicast, and L0 is used to distinguish MPLS multicast "neighbor label space".

When MPLS is based on the third layer (MPLS OVER IP), R1 establishes an LSP1 through the network L2 and R3; R2 establishes an LSP2 through the network L2 and R3. The two LSPs distribute labels based on upstream nodes R1 and R2 respectively.

The R1 node uses the 20 bits of L0 as the "neighbor label space" mapping information, and the R2 node uses the 20 bits of L0 as the "neighbor label space" mapping information. When the R3 node receives two messages, it distinguishes the "neighbor label space" according to the 20bit different mapping information values of Label0, so as to judge whether the message is from the R1 node or the R2 node. However, since the upstream nodes R1 and R2 may establish an LSP with the same downstream node, when distributing L0, the same L0 may be distributed. Then R3 cannot distinguish the "neighbor label space", that is, two different "neighbor label spaces" cannot be mapped through L0, and it is difficult for R3 to determine whether the packet comes from the R1 node or the R2 node. This will cause the packets sent by the R1 node and the packets sent by the R2 node to be forwarded by the R3 node only on one path. If the forwarding path of the message sent by the R1 node and the message sent by the R2 node to the R3 node is different, then the R3 node forwards it incorrectly, thereby increasing L0 to identify neighbor label space and waste resources.

Contents of the invention

In view of this, the present invention provides an MPLS multicast message forwarding method, device and system, which can realize fast and efficient multicast data forwarding.

The forwarding method of a kind of MPLS multicast message that the embodiment of the present invention provides, comprises:

receiving messages sent by at least two upstream nodes, where the messages include label information and address information of the upstream nodes, and the label information is allocated by the upstream nodes;

Determine the label space according to the address information, and search for a forwarding table in the label space;

Obtain message forwarding information from the forwarding table according to the label information;

Send the message according to the message forwarding information.

The embodiment of the present invention also provides a forwarding device of an MPLS multicast message, including:

The storage unit includes at least two label spaces, and forwarding tables are stored in the label spaces;

A receiving unit that receives messages sent by at least two upstream nodes, where the messages include label information and address information of the upstream nodes, and the label information is allocated by the upstream nodes;

The query unit determines the label space according to the address information of the received message, and searches for a forwarding table in the label space; obtains message forwarding information from the forwarding table according to the label information;

A sending unit, configured to send the message according to the message forwarding information.

The embodiment of the present invention also provides an MPLS multicast message transmission system, including at least one label switching router and a forwarding device;

The forwarding device receives messages sent by at least two upstream nodes, where the messages include label information assigned by the upstream nodes and address information of the upstream nodes; search forwarding tables from the label space according to the address information; and acquiring message forwarding information from the forwarding table according to the label information; sending the message according to the message forwarding information.

In the technical solution provided by the embodiments of the present invention, the upstream label allocation method is adopted, and the "source node address" (such as IP address, MAC address) information of the P2MP, MP2MP link or tunnel is used as the context for mapping the "neighbor label space", And divide neighbor label space according to source node address " information, determine label space according to the address information of received message, and search the forwarding table in this label space; Obtain message forwarding information from described forwarding table according to described label information; Send described message according to described message forwarding information.Can solve MPLS multicast upstream label distribution, neighbor label space identification problem on MP2MP, P2MP network, and make full use of bearer layer information, provide a scalable, common The forwarding method of the MPLS multicast message can effectively reduce the processing difficulty of the device.

Description of drawings

Fig. 1 is a schematic diagram of a kind of MPLS multicast message transmission system in the prior art;

Fig. 2 is the Ethernet frame structural representation that contains MPLS label stack in the embodiment of the present invention;

FIG. 3 is a schematic diagram of a PBT interface frame structure containing an MPLS label stack in an embodiment of the present invention;

Fig. 4 is a flow chart of a method for forwarding an MPLS multicast message provided in an embodiment of the present invention;

FIG. 5 is a schematic diagram of MPLS label space division in an embodiment of the present invention;

FIG. 6 is a schematic diagram of an MPLS multicast message transmission system provided in Embodiment 1 of the present invention;

FIG. 7 is a schematic diagram of an MPLS multicast message transmission system provided in Embodiment 2 of the present invention;

FIG. 8 is a schematic structural diagram of an MPLS multicast message forwarding device provided in Embodiment 3 of the present invention.

Detailed ways

MPLS is a switching technology that combines Layer 3 routing with Layer 2 attributes. It introduces a label-based mechanism that separates routing selection from data forwarding, and uses labels to specify the path for a packet to pass through the network. The MPLS network consists of a Label Switching Router (LSR) at the core and a Labeled Edge Router (LER, Labeled Edge Router) at the edge. The working process of label switching can be summarized as the following three steps:

(1) By the label distribution protocol (LDP, label distribution protocol) and the traditional routing protocol (OSPF, IS-IS, etc.), a routing forwarding table and a label mapping table are established in the LSR, wherein the routing forwarding table and the label mapping table are used for Determine the route.

(2) LER receives the IP packet, completes the third layer function, and adds a label to the IP packet; on the LER of the MPLS system exit, continues to forward after the label in the packet is removed;

(3) The LSR does not perform any third-layer processing on the packet, but only determines the route according to the label on the packet, the routing table and the label mapping table, and then forwards it through the switching unit.

MPLS retains the idea of hop-by-hop forwarding, and expands the local connection specified by the link layer based on different forwarding systems into an end-to-end forwarding mechanism. MPLS forwarding data packets include:

(a) Assignment and distribution of tags

Label allocation is to specify a label to be bound to a forwarding equivalence class (FEC, Forwardingequivalence class). FEC is a group of routing tables with the same forwarding behavior, including the Next Hop information, and the forwarding path and egress port information are the same. Usually, an FEC assigns a label to bind with it, and then distributes it to the upstream routing device supporting MPLS. Distribution refers to the process of notifying this binding upstream or downstream.

Label allocation methods can be divided into upstream label allocation and downstream label allocation. For example, MPLS packets are sent by LSR R1 to LSR R2. If the label is distributed by R2, it is "downstream label assignment", if the label is distributed by R1, it is "upstream label assignment". When using downstream label distribution, the distribution of labels is carried out in the opposite direction of data flow transmission, and the distribution process is initiated by the egress LSR, which is suitable for unicast applications. When using upstream label distribution, the distribution of labels is carried out along the direction of data flow transmission, and the distribution process is initiated by the ingress LSR, which is suitable for multicast situations.

(b) Establishment of LSP (Label Switching Path)

To establish an LSP, each LSR needs to do the following work: map the data flow packet to a certain FEC F1, allocate an unused label L1 (binding) for F1, and add entries (F1, L1) in the local label mapping table ; The binding information notifies the upstream LSR: add entries (L1, L2, Pout) in the local forwarding table, where L1 is the entry label, L2 is the exit label, and Pout is the output port.

(c) Transmission of data packets on LSP

After the LSP is established, data packets can be transmitted. The transmission relies on two tables of the LSR: the label mapping table and the routing and forwarding table. The label mapping table stores the mapping information between FEC and grouping. The entry form is (Fi, Li), Fi is the forwarding equivalence class, and Li is the corresponding label; the forwarding table indicates the egress label and output port corresponding to an ingress label, and the entry form is (Li1, Li2, Pi), where Li1 is the entry label, Li2 is the exit label, and Pi is the output port.

For example: Assume that the LSP has been established. For a data stream packet, the ingress LSR1 first maps it to the appropriate FEC F1, then attaches the corresponding label to the packet header according to the label mapping table information of LSR1, and then sends the packet according to the output port Pout in the LSR1 forwarding table Outgoing: After receiving the packet, the downstream LSR2 looks up the output label in the LSR2 mapping table according to the label of the input packet, performs label exchange, and sends the data packet to the output port specified in the LSR2 forwarding table; repeat this process until the packet reaches the egress LSR Finally, pop up the label, find the output port in the egress LSR forwarding table and send the data out.

Multicast (multicast) is mainly used in applications such as video conferencing, and this application needs to send a piece of data to multiple users at the same time. The multicast technology has the advantages of high bandwidth utilization, reducing the burden on the host/router, and avoiding troubles caused by ambiguous destination addresses, so as to meet this application.

With reference to Fig. 4, the embodiment of the present invention provides a kind of forwarding method of MPLS multicast message, comprises the steps:

S01. Receive a message sent by at least two upstream nodes, the message includes label information and address information of the upstream node, the label information is allocated by the upstream node, and the label information specifically includes as shown in Figure 2 L0 or L1;

S02. Determine the label space according to the address information of the received message, and search for a routing and forwarding table in the label space;

The number of the label spaces is pre-divided according to the number of upstream nodes. For example, if there are two upstream nodes adjacent to this node, the MPLS label space is divided into at least two label spaces, usually two label spaces . By analogy, if there are N upstream nodes adjacent to this node, divide the MPLS label space into N pieces.

S03. Obtain message forwarding information from the forwarding table according to the label information, where the message forwarding information includes at least one of the following:

Label operation type, output port information, next hop address information, link encapsulation type.

S04. Send the packet according to the packet forwarding information.

The address of the upstream node is an IP address or a MAC address.

The forwarding table is set and stored according to the preset.

The corresponding relationship between address information and the label space is pre-stored in a content index address storage unit (TCAM, Ternary Content Addressable Memory), and the determination of the label space specifically includes:

Search the address information of the received message in the content index address storage unit TCAM, and determine the corresponding label space according to the found address information.

In a specific embodiment of the present invention, the "source node address" information of the P2MP, MP2MP link or tunnel is used as the context for mapping the "neighbor label space". For example, based on Ethernet Eth, PBB (multi-protocol encapsulation, PBT) uses S-MAC as the "neighbor label space" mapping information, PBT (Provider Backbone Transport), called: operator backbone bridge count, its basic idea is to Add the carrier's Ethernet frame header before the user's Layer 2 packet. As shown in Figure 2, it is an Ethernet frame format containing an MPLS label stack, where EthType is 0x8847/0x8848 to indicate that the frame carries an MPLS message; as shown in Figure 3, it is a PBT interface frame format with an MPLS label stack ; Generic Routing Encapsulation (GRE, Generic Routing Encapsulation), IP Tunnel uses S-IP as the "neighbor label space" mapping information; P2MP MPLS Tunel uses Label as the "neighbor label space" mapping information. The following will be described in conjunction with specific embodiments.

General routing encapsulation GRE is to encapsulate data packets of certain network layer protocols (such as: IP, IPX, Apple Talk, etc.), so that these encapsulated data packets can be transmitted in another network layer protocol (such as IP) , the message format is as follows:

transport protocol header GRE head raw packet

link layer protocol IP GRE MPLS, IPX, IP

IP Tunnel is IP tunnel technology, its message format:

transport protocol header IP MPLS message

MPLS Tunnel is MPLS tunneling technology, its message format

transport protocol header Label label stack Payload

Embodiment one

In the forwarding solution of the MPLS multicast message in the embodiment of the present invention, an upstream label distribution method is adopted. According to the definition of RFC3031, using the incoming label mapping index ILM (Incoming Label Map) Index, the label assigned by the upstream node is mapped to a set of Next Hop Label Forward Entry (NHLFE, Next Hop Label Forward Entry) or an NHLFE, while NHFLE It is also the mapping of the forwarding equivalence class FEC. The output port information, next hop host, label operation type, next hop label, etc. can be obtained from NHFLE. Since the label Label has a total of 20 bits, the maximum ILM space is 1M. First divide the number of label spaces according to the number of upstream nodes. In this embodiment, there are two upstream nodes adjacent to this node, namely R1 and R2. Then, the MPLS label space is divided into two label spaces SP1 and SP2, as As shown in Figure 5:

SP1 (address 0-4K) assigns to the label Label of R1 to search and forward;

SP2 (with an address of 4K-1M) assigns the label Label of R2 to search and forward.

The source IP address SIP is used as the information for mapping the "neighbor label space", specifically,

With reference to Fig. 6, the forwarding method of the MPLS multicast message that the embodiment of the present invention provides, comprises the following steps:

101. Establish two label switching paths LSP1 and LSP2 from RI to R3 and from R2 to R3 with R1 and R2 as upstream nodes and R3 as downstream nodes;

102. R1 and R2 respectively send multicast packets containing active IP addresses to R3;

The multicast packet Packetl sent by R1 includes source IP address SIP1, destination IP address DIP1, labels L0- and L1, and payload Payloadl, namely

SIP1 DIP1 L0 L1 Payload1

The multicast packet Packet2 sent by R2 includes source IP address SIP2, destination IP address DIP2, labels L0- and L1, and payload Payload2, namely

SIP2 DIP2 L0 L1 Payload2

103. When R3 receives Paket1 and Packet2, since the DIP is both R3, R3 will further analyze the packet label Label;

For the message sent by R1, in the label space SP1 of R3, the Label of the Label forwarding information table (assigned to R1, with an address of 0-4K) is searched for forwarding information;

For the message sent by R2, the Label in the Label forwarding information table (distributed to R2, address 4K～1M) in the label space S2 of R3 is also searched for forwarding information;

In addition, if R3 is provided with a content index address memory TCAM, in this case, R3 uses the received SIP to perform a matching search in TCAM after the received message, because the SIP1 of Packet1 and the SIP2 of Packet2 are different, The SIP addresses of the two packets are matched to different addresses in the TCAM to determine the label space SP1 or SP2, as follows:

For Packetl's SIP1, through TCAM search, the corresponding label space S1 (0~4K) will be uniquely obtained;

For the SIP2 of Pakcet2, the corresponding label space S2 (4K-1M) will be uniquely obtained through the search of the TCAM.

For the Label of Packetl, first judge whether the label value is in the SP1 space (0 ~ 4K), and consider the label whose label value is not in the S1 as an illegal label; for the legal label, use the Label as the lookup index of the ILM table and query the ILM table , get the correct forwarding information;

For the Label of Packet2, first judge whether the label value is in the SP2 space (0~(1M-4K)), and consider the label whose label value is not on SP2 as an illegal label; for a legal label, use the Label plus an offset of 4K address, get the index of querying the ILM table, query the ILM table, and get the correct forwarding information;

After the label space is clearly separated, if the L0 distribution of Packetl and Packet2 is the same, the index of Packetl to check the ILM table is L0 itself, and the index of Pakct2 to check the ILM table is L0+4K;

It can be seen that, through the uniqueness of SIP, the Label spaces of Packet1 and Packet2 can be correctly distinguished.

The TCAM matching method can be through SIP matching or SIP+L0 matching, but SIP is the information that must be matched; since SIP+L0 is used as matching information, it occupies a lot of TCAM resources, so SIP is usually used as matching information.

Embodiment two

This embodiment is basically the same as the first embodiment above, except that the source MAC address is used in the solution of this embodiment to identify and determine which sender LSR the multicast message comes from.

Referring to Figure 7, R1 and R2 provide network L2 to establish two label switching paths LSP1 and LSP2 from RI to R3 and R2 to R3; R1 and R2 respectively send multicast packets to R3;

The multicast packet Packetl sent by R1 includes source MAC address SMAC1, destination MAC address DMAC1, labels L0- and L1, and payload Payload1, namely

DMAC1 SMAC1 L0 L1 Payload1

The multicast packet Packet2 sent by R2 includes source MAC address SMAC2, destination MAC address DMAC2, labels L0- and L1, and payload Payload2, namely

DMAC2 SMAC2 L0 L1 Payload2

Since SMAC1 of Packet1 and SMAC2 of Packet2 are different, the SIP addresses of the two packets are matched to different addresses in the TCAM, so as to determine the label space SP1 or SP2.

Embodiment Three

Referring to Fig. 8, the present embodiment provides a forwarding device 500 of an MPLS multicast message, including:

The storage unit 510 includes at least two label spaces, and forwarding tables are stored in the label spaces;

The number of the label spaces is pre-divided according to the number of upstream nodes. For example, if there are two upstream nodes adjacent to this node, the MPLS label space is divided into at least two label spaces, usually two label spaces . By analogy, if there are N upstream nodes with this node, divide the label space into N number.

The receiving unit 520 is configured to receive messages sent by at least two upstream nodes, where the messages include label information and address information of the upstream nodes, and the label information is allocated by the upstream nodes;

Usually, the address of the upstream node is an IP address or a MAC address.

The query unit 530 determines the label space according to the address information of the received message, and searches for a forwarding table in the label space; obtains message forwarding information from the forwarding table according to the label information, and the forwarding information includes at least the following one:

Label operation type, output port information, next hop address information, link encapsulation type. ;

The sending unit 540 is configured to send the message according to the message forwarding information.

The embodiment of the present invention also provides an MPLS multicast message transmission system, including at least one label switching router and a forwarding device;

The forwarding device receives messages sent by at least two upstream nodes, where the messages include label information assigned by the upstream nodes and address information of the upstream nodes; search forwarding tables from the label space according to the address information; and acquiring message forwarding information from the forwarding table according to the label information; sending the message according to the message forwarding information.

The forwarding device includes:

The storage unit includes at least two label spaces, and forwarding tables are stored in the label spaces;

A receiving unit that receives messages sent by at least two upstream nodes, where the messages include label information and address information of the upstream nodes, and the label information is allocated by the upstream nodes;

The query unit determines the label space according to the address information of the received message, and searches for a forwarding table in the label space; obtains message forwarding information from the forwarding table according to the label information;

A sending unit, configured to send the message according to the message forwarding information.

More suitably, the forwarding device is physically integrated with the label switching router, that is, the forwarding device cannot be set in one of the label switching routers.

In summary, in the technical solution provided by the embodiments of the present invention, the upstream label distribution method is adopted, and the "source node address" (such as IP address, MAC address) information of the P2MP, MP2MP link or tunnel is used as the mapping "neighbor Label space” context, and divide the neighbor label space according to the source node address” information, determine the label space according to the address information of the received message, and search the forwarding table in the label space; according to the label information from the forwarding table Obtain message forwarding information; Send described message according to described message forwarding information.Can solve MPLS multicast upstream label distribution, neighbor label space identification problem on MP2MP, P2MP network, and make full use of bearing layer information, provide An extensible and general MPLS multicast message forwarding method can effectively reduce the processing difficulty of the device.

Obviously, those skilled in the art should understand that each unit or each step of the present invention described above can be realized by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed in a network formed by multiple computing devices Optionally, they can be implemented with program codes executable by a computing device, so that they can be stored in a storage device and executed by a computing device, or they can be made into individual integrated circuit modules, or they can be integrated into Multiple units or steps are fabricated into a single integrated circuit module to achieve. As such, the present invention is not limited to any specific combination of hardware and software.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (13)

1. the retransmission method of a MPLS multicast message is characterized in that, comprising:

Receive the message that at least two upstream nodes send, this message comprises the address information of label information and said upstream node, and said label information is distributed by said upstream node;

Confirm Label space according to said address information, and search transmitting in the said Label space;

Obtain the message forwarding information according to said label information from said transmitting;

Send said message according to said message forwarding information.

2. retransmission method as claimed in claim 1 is characterized in that, said message forwarding information comprise following one of at least:

Tag operational type, output port information, next-hop address information, link encapsulated type.

3. retransmission method as claimed in claim 1 is characterized in that, the address of said upstream node is IP address or MAC Address.

4. retransmission method as claimed in claim 1 is characterized in that, the quantity of said Label space is divided according to said upstream node number in advance.

5. retransmission method as claimed in claim 1 is characterized in that,

Said transmitting according to support MPLS multi-service information is provided with in advance and stores.

6. retransmission method as claimed in claim 1 is characterized in that, the corresponding relation of said address information and Label space is stored among the content indexing address storaging unit TCAM in advance, and said definite Label space specifically comprises:

The address information of in content indexing address storaging unit TCAM, searching the message that receives, and confirm pairing Label space according to the address information that is found.

7. retransmission method as claimed in claim 1 is characterized in that, also comprises:

Distinguishing said label information according to protocol type is distributed by said upstream node.

8. the retransmission unit of a MPLS multicast message is characterized in that, comprising:

Memory cell comprises at least two Label space, stores in the said Label space and transmits;

Receiving element receives the message that at least two upstream nodes send, and this message comprises the address information of label information and said upstream node, and said label information is distributed by said upstream node;

Query unit is confirmed Label space according to the address information of reception message, and searches transmitting in this Label space; Obtain the message forwarding information according to said label information from said transmitting;

Transmitting element sends said message according to said message forwarding information.

9. retransmission unit as claimed in claim 8 is characterized in that, said forwarding information comprise following one of at least:

Tag operational type, output port information, next-hop address information, link encapsulated type.

10. retransmission unit as claimed in claim 8 is characterized in that, the address of said upstream node is IP address or MAC Address.

11. retransmission unit as claimed in claim 8 is characterized in that, the quantity of said Label space is divided according to said upstream node number in advance.

12. a MPLS multicast message transmission system is characterized in that, comprises at least one LSR and retransmission unit;

Said retransmission unit comprises:

Memory cell comprises at least two Label space, stores in the said Label space and transmits;

Receiving element receives the message that at least two upstream nodes send, and this message comprises the address information of label information and said upstream node, and said label information is distributed by said upstream node;

Query unit is confirmed Label space according to the address information of reception message, and searches transmitting in this Label space; Obtain the message forwarding information according to said label information from said transmitting;

Transmitting element sends said message according to said message forwarding information.

13. system as claimed in claim 12 is characterized in that,

Described retransmission unit is arranged in one of them said LSR.

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