JP2006080682A - Point-to-multipoint mpls (multi-protocol label switching) communication method and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To build up a multicast MPLS transfer network capable of efficiently multicast-transferring P2MP traffic with high performance. <P>SOLUTION: In the case of setting a LSP interconnecting PE nodes, a P2MP session object, a P2MP state identifier, and a leaf state identifier are set to a message transmitted to the LSP on a tree branched by a relay PE node and to the relay PE node, the message is transmitted up to a reception leaf node via the relay PE node, and each relay PE node and each reception leaf node return the received message (Resv) to an upperstream node so that a P2MP label switching path is set between the transmission node and the reception leaf node. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a point-to-multipoint MPLS communication method and system, and more particularly, to perform traffic forwarding for point-to-multipoint (P2MP) communication while guaranteeing QoS while efficiently performing TE (Traffic Engineering) on a network. P2MP MPLS technology for setting up the P2MP MPLS transport route
The present invention relates to a communication method and system.

As an MPLS signaling protocol, there is RSVP-TE (Resource Reservation Protocol-Traffic Engineering) (see, for example, Non-Patent Document 1).
“RSVP-TE: Extensions to RSVP for LSP Tunnels”, RFC3209

  However, since the above RSVP-TE is an MPLS signaling protocol that sets a P2P LSP (Label Switched Path), when a P2MP communication traffic is transferred, a plurality of destinations of P2MP communication are transmitted at the transmitting PE provider edge node. Since it is necessary to set multiple LSPs at the receiving PE node, copy the received traffic at the transmitting PE node, and copy it to multiple P2P LSPs that have been set up, the copy performance at the transmitting PE node will be reduced. However, there is a problem of reducing the transfer efficiency of the network.

  The present invention has been made in view of the above points. The MPLS signaling protocol of RSVP-TE is extended so that P2MP traffic can be copied at an optimal branch point in the provider network, and the optimum P2MP traffic in the entire network can be copied. An object of the present invention is to provide a P2MP MPLS communication method and system capable of copying.

  FIG. 1 is a diagram for explaining the principle of the present invention.

According to the present invention (Claim 1), in an MPLS communication network, a PE node arranged at the boundary of the MPLS network forwards P2MP communication traffic including IP multicast traffic to the PE nodes arranged at the plurality of boundaries. In the point-to-multipoint MPLS communication method,
The sending PE node
Up to multiple receiving PE nodes (hereinafter referred to as receiving leaf nodes), copy points are set up at multiple relay PE nodes in the PE using the MPLS signaling protocol, and a P2MP tree-shaped label switching path (LSP) is established. By setting the MPLS transfer route setting step to set the MPLS transfer route,
Based on the information in the MPLS table set in the MPLS transfer route setting step, performs an MPLS packet transfer step for transferring an MPLS packet, and
MPLS forwarding route setting step
When setting the P2MP tree-shaped LSP at the sending PE node,
P2MP that consists of logical P2MP destination group address of P2MP LSP, tunnel identifier, and extended P2MP tunnel identifier to identify and manage P2MP sessions based on MPLS protocol that guarantees QoS and enables TE A P2MP session object definition step for defining a session object in the signaling protocol;
Further, in order to identify and manage a P2MP sender template, a P2MP LSP transmission address and a P2MP LSP identifier are added to the sender template information, and a P2MP state identifier representing the P2MP path state state is added to the sender template. A sender template object definition step for defining a sender template object by additionally defining information,
Furthermore, in order to identify and manage the state of a single receiving leaf node that constitutes P2MP, a receiving address that becomes a receiving leaf node is defined, and partial P2P path information from the transmitting node to the receiving leaf node is identified. A leaf object definition step for defining a leaf object by defining a leaf state identifier for management;
A path message generation step for storing the P2MP session object defined in the P2MP session object definition step, the sender template object defined in the sender template object definition step, and the leaf object defined in the leaf object definition step in the path message;
A path message transmitting step of transmitting a path message from the transmitting PE node to each receiving node of the P2MP LSP to be set;
In the relay PE node and receiving leaf node that received the path message,
P2MP label switching that sets the P2MP label switching path from the sending node to the receiving node on the MPLS table by returning the received path message containing the P2MP session object, sender template object, and leaf object to the upstream node. A routing step;
Based on the information in the MPLS table set in the P2MP label switching path setting step, a transfer step for transferring an MPLS packet,
To do.

Further, the present invention (Claim 2), in the path message generation step,
The sending PE node stores the P2MP session and sender template information in the path message as P2MP path state information for all nodes on the set P2MP LSP path.
In the P2MP label switching path setting step,
Each node on the set P2MP LSP path sets leaf state information corresponding to the reception leaf node accommodated downstream of each node in the path message as lower information of the P2MP session and sender template information.

In addition, the present invention (Claim 3), when setting a point-to-multipoint MPLS path,
The sending PE node
Add the path information from the sending PE node to the single receiving leaf node and the corresponding leaf state information to the P2MP session information and sender template information, store it in the path message, and send it to the receiving leaf node ,
The receiving leaf node
A step of setting the P2MP LSP of the P2MP portion corresponding to the path message is performed by transmitting the received message for the path message to the upstream node,
The sending PE node
Multiple path state information from the sending PE node to multiple receiving leaf nodes and multiple corresponding leaf state information are added to the P2MP session information and sender template information, stored in the path message, and sent to multiple receiving leaf nodes Perform partial P2MP LSP setting / update step
P2MP LSP setting / updating steps
When setting a new partial P2MP LSP,
By assigning a new ID to the P2MP state identifier and a new ID to the leaf state identifier, a new setting step is performed to newly set the state information on the node on the route.
When adding a partial P2MP LSP to the configured partial P2MP LSP,
A sender template object with a P2MP state identifier that has the same state ID as the P2MP LSP state information that has already been set, and a leaf object that has a leaf state ID corresponding to the leaf LSP to be additionally set are stored in a path message and transmitted. By doing this, the additional setting step to perform additional setting of partial P2MP LSP in the same state is performed,
When deleting a partial P2MP route that reaches a single receiving leaf node of a configured partial P2MP LSP,
The leaf information corresponding to the P2MP session information and sender template information is stored in the Path Tear message and sent from the sending PE node to the receiving leaf node to be deleted, and only the corresponding lower leaf state information is set and deleted from the P2MP LSP Then, a deletion step of deleting the corresponding P2P route is performed.

Further, the present invention (Claim 4) provides the deletion step,
When deleting partial P2MP routes that reach multiple receiving leaf nodes of the configured P2MP LSP,
P2MP session information and multiple leaf information corresponding to sender template information are stored in a Pastier message and sent from the sending PE node to multiple receiving leaf nodes, and only the corresponding lower-level leaf state information is set. Delete multiple corresponding P2P routes by deleting from the LSP,
When deleting a receiving leaf node from a configured P2MP LSP:
The leaf template with the same leaf identifier as the leaf state ID corresponding to the sender leaf information corresponding to the sender leaf information that has already been set and the sender template information that has the same state ID as the P2MP state identifier of the configured P2MP LSP By storing, a partial P2MP LSP that is not in the same state is deleted.

In addition, the present invention (Claim 5), after the end of the P2MP LSP setting / updating step,
At the sending PE node
A sender template having a state ID obtained by incrementing the P2MP state ID representing the state of the entire P2MP state, partial additional information such as route information, and path related information reflecting the partial deletion information is stored in the path message as a refresh message. Perform steps to notify downstream nodes,
The downstream node is
Detects a change in the state ID, detects that a path message is sent downstream as a trigger message for the purpose of state matching, and immediately passes the path message as a trigger message to the corresponding downstream path Take the steps to send to
Each downstream node that receives the trigger message
Based on the state ID of the trigger message, a step of independently repeating the refresh cycle is performed.

Further, the present invention (Claim 6), in each node on the P2MP path,
When the path state is refreshed, even if there is a difference in leaf information included in the path message having the same P2MP state ID, it is processed as a message for refreshing the same state.

  FIG. 2 is a principle configuration diagram of the present invention.

According to the present invention (Claim 7), in an MPLS communication network, a PE node arranged at the boundary of the MPLS network forwards P2MP communication traffic including IP multicast traffic to the PE nodes arranged at the plurality of boundaries. A point-to-multipoint MPLS communication system having a transmitting PE node 1, a relay PE node 2, and a receiving PE node 3,
The sending PE node 1
Up to multiple receiving PE nodes 3 by using MPLS signaling protocol, a copy point is set up in multiple relay PE nodes 2 in the PE, and a P2MP tree-shaped LSP is set up to set an MPLS transfer path MPLS Transfer path setting means 10;
MPLS packet transfer means for transferring an MPLS packet based on the information of the MPLS table set by the MPLS transfer route setting means,
The MPLS transfer path setting means 10 of the transmission PE node 1
When setting the P2MP tree-shaped LSP,
P2MP session composed of logical P2MP destination group address of P2MP LSP, tunnel identifier, and extended P2MP tunnel identifier to identify and manage P2MP session based on MPLS capable of TE with guaranteed QoS P2MP session object defining means 11 for defining an object in a signaling protocol;
Further, in order to identify and manage a P2MP sender template, a P2MP LSP transmission address and a P2MP LSP identifier are added to the sender template information, and a P2MP state identifier representing the P2MP path state state is added to the sender template information. A sender template object defining means 12 for defining a sender template object by additionally defining;
Furthermore, in order to identify and manage the state of a single receiving leaf node that constitutes P2MP, a receiving address that becomes a receiving leaf node is defined, and partial P2P path information from the transmitting node to the receiving leaf node is identified. A leaf object defining means 13 for defining leaf state identifiers for management;
A path message generating means 14 for storing a P2MP session object defined by the P2MP session object defining means 11, a sender template object defined by the sender template object defining means 12, and a leaf object defined by the leaf object defining means 13 in a path message. When,
A path message transmitting means 15 for transmitting a path message from the transmitting PE node 1 to each receiving node 3 of the P2MP LSP to be set;
The relay PE node 2 on the LSP path on the P2MP tree set by the sending PE node 1 is
A message transfer means 21 for transferring a path message transmitted from the transmission PE node 1 or an upstream node to a downstream node;
P2MP label switching that sets the P2MP LSP path between the sending node 1 and the receiving node in the MPLS table by returning the received path message containing the P2MP session object, sender template object, and leaf object to the upstream node. Route setting means 22;
Transfer means for transferring an MPLS packet based on information in the MPLS table set by the P2MP label switching path setting means 22.

Further, the present invention (Claim 8) is provided in the path message generation means 14 of the transmission PE node 1,
As a P2MP path state information for all nodes on the set P2MP LSP path, including means for storing the P2MP session, sender template information in the path message,
The P2MP label switching route setting means 22 of the relay PE node 2
Means for setting leaf state information corresponding to a reception leaf node accommodated downstream of each node in a path message as lower information of the P2MP session and sender template information.

Further, the present invention (claim 9) is the transmission PE node 1,
When setting up a point-to-multipoint MPLS path,
There is a means for adding route state information corresponding to the route from the transmitting PE node to a single receiving leaf node to the P2MP session information and sender template information, storing it in the path message, and transmitting it to the receiving leaf node. And
Each relay PE node 2
A plurality of leaf state information corresponding to a plurality of route information from the transmitting PE node 1 to a plurality of receiving leaf nodes is added to the P2MP session information and the sender template information, and stored in the path message to the plurality of receiving leaf nodes. Having means for transmitting,
The plurality of receiving leaf nodes 3
A means for setting a P2MP LSP of a plurality of P2P parts corresponding to the path message by transmitting a received message for the path message to an upstream node;
The sending PE node 1
When newly setting a partial P2MP LSP, a new setting means for newly setting state information to a node on the route by assigning a new ID to the P2MP state identifier and a new ID to the leaf state identifier;
When a partial P2MP LSP is additionally set to the set partial P2MP LSP, a sender template object having a P2MP state identifier having the same state ID as the state information of the already set P2MP LSP is added to the leaf LSP to be additionally set. An additional setting means for performing additional setting of a partial P2MP LSP in the same state by storing and transmitting a leaf object having a corresponding leaf state ID in a path message;
When deleting a partial P2MP route that reaches a single receiving leaf node of the configured partial P2MP LSP, the leaf PE information that corresponds to the P2MP session information and sender template information is stored in the Path Tear message and sent to the PE node Delete means for deleting only the corresponding lower-level leaf state information from the set P2MP LSP and deleting the corresponding P2P path.

In the present invention (Claim 10), when the deletion unit deletes the partial P2MP route reaching the plurality of receiving leaf nodes 3 of the set P2MP LSP, the plurality of leaves corresponding to the P2MP session information and the sender template information are deleted. The information is stored in the pastier message, transmitted from the transmitting PE node 1 to the plurality of receiving leaf nodes 3, and only the corresponding lower-level leaf state information is deleted from the set P2MP LSP, and the corresponding plurality of P2P paths are Means to delete,
When deleting a reception leaf node from the configured P2MP LSP, the leaf state corresponding to the sender template information and the already configured reception leaf state with the same state ID as the P2MP state identifier of the configured P2MP LSP Means for deleting a partial P2MP LSP that is not in the same state by storing leaf information having the same leaf identifier as the ID in the pastier message.

Further, according to the present invention (claim 11), the transmitting PE node 1
After completion of the P2MP LSP setup / update step, sender template with a state ID that increments the P2MP state ID by 1 indicating the state of the entire P2MP state, partial additional information such as route information, and path related information that reflects partial deletion information Is stored in a path message as a refresh message and notified to a downstream node,
The relay PE node 2
Detects a change in state ID, detects that a path message is sent as a trigger message downstream for the purpose of state matching, and uses the path message as a trigger message for the corresponding downstream path Have means to send immediately to downstream nodes,
Each downstream node that receives the trigger message
And means for independently repeating the refresh cycle based on the state ID of the trigger message.

  The present invention (Claim 12) refreshes the same state in the relay PE node 2 even if there is a difference in leaf information included in the path message having the same P2MP state ID when the path state is refreshed. Means for processing as a message.

  As described above, according to the present invention, it is possible to construct a multicast MPLS transfer network that can efficiently and efficiently transfer P2MP traffic with high performance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, an operation will be described in which the PE node arranged at the boundary of the MPLS network performs MPLS transfer of the P2MP communication traffic including the IP multicast traffic to the PE nodes arranged at the plurality of boundaries in the MPLS communication network.

  In the following description, #A shown in FIG. 1 is a transmission PE node, #B, #C, and #F are relay PE nodes, and #D, #E, #G, and #H are reception PE nodes.

  FIG. 3 shows a configuration of each PE node in the embodiment of the present invention.

  The PE nodes 100, 200, and 300 shown in the figure have protocol processing units 110, 210, and 310, and MPLS transfer units 120, 220, and 320, each including a path state processing unit and a reserve state processing unit. The MPLS transfer unit 220 of the relay PE node 200 searches the search table based on the input label included in the header of the input MPLS packet, determines the output label used for the next transfer, and performs switching. It has a function of copying packets for the number of transfer destinations, adding outgoing labels, and transferring them to downstream nodes. Note that the MPLS transfer units 110 and 310 of the transmission PE node 100 and the reception leaf node 300 do not copy packets.

  First, the protocol processing unit 110 of the transmission PE node #A installs copy points in a plurality of relay PE nodes in the PE using the MPLS signaling protocol up to a plurality of reception PE nodes in the path state processing unit 111, An MPLS transfer path is set by setting a P2MP tree-shaped LSP.

  As a method, the transmitting PE node 100 uses a P2MP LSP logical P2MP destination group address, a tunnel identifier, a P2MP LSP to identify and manage a P2MP session based on RSVP-TE (RFC3209) as a P2PM session object. And an extended P2MP tunnel identifier is defined in the signaling protocol. Specifically, a field for a P2MP session object for newly identifying a P2MP session is defined in a path (setting request) message. In the MPLS signaling protocol, a path (setting request) message is sent as packet data (bit string) on the IP and transfer network. In other words, this means that a new field for the P2MP session is defined in the message, and the message format is changed.

  The relay PE node 200 that has received the path message receives the path (setting request) message as a packet, looks at the head header of the packet, recognizes that it is an MPLS control packet, and controls the MPLS node control block unit. The message is internally transferred to (not shown). Thereafter, each path element processing unit decodes each object element and P2MP session information included in the path message, and determines the meaning of the path message. As a result of the determination, if the path message is a setting request message, the path information and QoS information of the path to be set are extracted, a transfer path corresponding to the data transfer path of its own node is secured, and the MPLS transfer unit 220 When an MPLS packet arrives at a packet, a search table (not shown) is set so that label switching can be performed. In the case of P2MP, label switching can be performed while branching at P2MP.

  In the case of the relay PE node 200, since the transfer is still necessary downstream, the path message is transferred to the downstream node. Furthermore, when this path message arrives at a downstream node (leaf node), the receiving PE node confirms the above reservation and receives the set route back to the upstream PE node as a path setting confirmation message (path setting confirmation). Forward the message.

  When the relay PE node 200 receives this reception (path setting confirmation) message, the relay PE node 200 transfers the message to the reserve state processing unit 220 in the relay PE node 00, and the reserve state processing unit 220 interprets the request content and the path is determined. Is determined, the data transfer of the transfer path block is confirmed. Thereby, the data plane can be transferred. Further, when message transfer is required for the upstream node, the message is transferred to the upstream node.

  Further, the path state processing unit 111 of the transmission PE node 100 sends a P2MP LSP transmission address and a P2MP LSP identifier as a sender template object for identifying a sender in order to identify and manage a P2MP sender template. In addition to the template information, a P2MP state identifier indicating the path state of the P2MP is additionally set in the sender template information.

  Further, the path state processing unit 111 of the transmission PE node 100 identifies a single leaf state constituting the P2MP as a leaf object for specifying a route from the source to any one leaf node of the P2MP tree. In order to manage, a reception address as a leaf is defined, and a leaf identifier for identifying and managing partial P2P path information from the transmission node to the reception leaf node is defined.

  Next, the path state processing unit 111 of the transmission PE node 100 stores the defined P2MP session object, sender template object, and leaf object in the path message.

  When created by the above processing, a path message is transmitted to the relay PE node 200 as a path setting request via the MPLS transfer unit 120.

  The MPLS transfer units 220 and 320 of the relay PE node 200 and the reception PE node 300 return the transmission message of the path setting confirmation by storing the P2MP session object, the sender template object, and the leaf object to the upstream node. A P2MP label switching path is set between the node 100 and the relay / reception node.

  When the P2MP label switching path is set, the path state processing unit 111 of the transmission PE node 100 transmits P2MP path state information as P2MP path state information to the path message transmitted to all nodes on the set P2MP LSP path. Stores session and sender template information. Further, the reserve state processing unit 212 of each relay PE node 200 on the set P2MP LSP path converts the leaf state information corresponding to the reception leaf node 300 accommodated downstream of each node into the P2MP session and the sender template information. Set in the received message as lower information.

  Furthermore, when the P2PMP MPLS path is set, the path state processing unit 111 of the transmission PE node #A transmits the leaf information corresponding to the path information from the transmission PE node #A to a single reception leaf node (for example, #D). The state information is added to the P2MP session information and the sender template information, stored in the path message, and transmitted to the reception leaf node (#D) via the MPLS transfer unit 120.

  As a result, the reserve state processing unit 312 of the reception leaf node #D sets the P2MP LSP of the P2MP portion corresponding to the path message, based on the reception message for the path message. The path state processing unit of each PE node (#B to #H) to the transmission PE node #A and the reception leaf node has a plurality of pieces of information corresponding to a plurality of path information from the transmission PE node #A to the plurality of reception leaf nodes. The leaf state information is added to the P2MP session information and the sender template information, stored in a path message, transmitted to a plurality of receiving leaf nodes, and reserved state processing units 312 of the plurality of receiving leaf nodes (#D to #H). Transmits a received message for the path message to the upstream node, thereby setting P2MP LSPs of a plurality of corresponding P2P parts.

  As a process of setting a partial P2MP LSP, when a new partial P2MP LSP is set, the transmitting PE node 100 assigns a new ID to the P2MP state identifier and a new ID to the leaf state identifier. State information is newly set in the node.

  When a partial P2MP LSP is additionally set to the set partial P2MP LSP, it is additionally set with a sender template object provided with a P2MP state identifier having the same state ID as the state information of the already set P2MP LSP. By storing and transmitting a leaf object having a leaf state ID corresponding to the leaf LSP in a path message, a partial P2MP LSP is additionally set in the same state.

  Also, when deleting a partial P2MP route that reaches a single receiving leaf node of a configured partial P2MP LSP, the leaf PE information that corresponds to the P2MP session information and sender template information is stored in the pastia message and sent to the PE node Only the corresponding lower leaf state information is deleted from the P2MP LSP set in the search (MPLS) table, and the corresponding P2P path is deleted.

  When deleting a partial P2MP route that reaches a plurality of receiving leaf nodes 300 of the P2MP LSP set in the search table, the P2MP session information and a plurality of leaf information corresponding to the sender template information are included in the pastia message. Store and transmit from the transmitting PE node 100 to the plurality of receiving leaf nodes 300 and delete only the corresponding lower-level leaf state information from the P2MP LSP set in the search table to delete the corresponding plurality of P2P paths.

  Also, when deleting a received leaf node from the configured P2MP LSP, it corresponds to the sender template information having the same state ID as the P2MP state identifier of the configured P2MP LSP and the already configured received leaf state. The leaf information having the same leaf identifier as the leaf state ID to be stored is stored in the pastier message, thereby deleting the partial P2MP LSP that is not in the same state.

  When the P2MP LSP setting / updating process is completed, the transmitting PE node 100 sends a sender template having a state ID obtained by incrementing the P2MP state ID indicating the state of the entire P2MP state by one, partial additional information such as path information, and partial deletion. The path related information reflecting the information is stored in the path message as a refresh message and notified to the downstream node.

  The downstream node that has received the refresh message from the sending PE node 100 detects the change in the state ID information, and confirms that the path message is sent as a trigger message downstream for the purpose of state matching. The path message is immediately sent as a trigger message to the corresponding downstream path. As a method for detecting a change in the state ID information, for example, it is determined that a newly transmitted message corresponds to a state different from the old message due to a change (increase by +1). As a result, a message for the new state is sent as a trigger message.

  Each downstream node that has received the trigger message repeats the refresh cycle independently based on the state ID of the trigger message.

  Note that each node (transmission PE node, relay PE node, reception leaf node) on the P2MP route described above differs in the leaf information included in the path message having the same P2MP state ID when the path state is refreshed. Even if there is a message, the same state is processed as a refresh message.

  Next, the operation of each PE node is shown in detail.

  4 to 6 are operation examples in one embodiment of the present invention, the operations of 0) to 9) are shown in FIG. 4, the operations of 10) to 16) are shown in FIG. 5, and 17) to 23 The operation of) is shown in FIG.

  0) In the path state processing unit 111 of the protocol processing unit 110 of the transmission PE node 100, P2MP LSP information (P2MP session, sender template, leaf, route information, QoS information) is set in the path message.

  1) The path state processing unit 111 sends a path message for which information setting has been completed to the MPLS transfer unit 120.

  2) The MPLS transfer unit 120 transmits the message set by the protocol processing unit 110 to the relay PE node 200.

  3) When the relay PE node 200 receives the path message via the MPLS transfer unit 220, the path state processing unit 211 performs decoding such as session identification processing, new or refresh processing on the path message.

  4) Next, the path state processing unit 211 determines whether or not P2MP LSP setting is possible. If yes, information (P2MP session, sender template, leaf, route information, QoS information) is included in the path message. Set up.

  5) Pass the path message in which the information is set to the MPLS transfer unit 220.

  6) The MPLS transfer unit 220 transmits a path message to the receiving PE node 300.

  7) In the path state processing unit 311 of the protocol processing unit 310 of the receiving PE node 300, the path message decoding process is performed in the same manner as in the above 3).

  8) Further, similarly to the above 4), it is determined whether or not P2MP LSP setting is possible, and if it is possible, information is set in the path message.

  9) A path message is transmitted to the downstream PE node via the MPLS transfer unit 320.

  10) The reserved state processing unit 312 of the receiving PE node 300 sets the incoming label (L1) and outgoing label (none) in the search table of the MPLS forwarding unit 320 based on the P2MP SLP forwarding path label setting processing and the received message. Perform the path setting process.

  11) The reserved state processing unit 312 passes the received message to the MPLS transfer unit 320.

  12) When the MPLS transfer unit 320 obtains the input label (L1) and the output label (none) as the label information of the received message, it updates the label of the search table (input label = L1, output label = deletion) and receives it. An incoming label (L1) is added to the header of the message and transmitted to the relay PE node 200.

  13) The reserve state processing unit 212 of the relay PE node 200 receives the received message to which the incoming label (L1) is given from the receiving PE node 300 and the incoming label (L0) obtained from the other receiving PE node. A message is acquired, and based on these received messages, a route setting instruction based on the label information (incoming label (L2), outgoing label (L1)) and the received message is given to the MPLS transfer unit 220.

  14) The reserved state processing unit 212 passes the received message to the MPLS transfer unit 220.

  15) The MPLS transfer unit 220 searches the search table, attaches the incoming label (L2) to the header of the received message, and transmits it to the receiving PE node 100.

  16) The reserved state processing unit 112 of the receiving PE node 100 performs the process of setting the label information as input label = none and the output label = L2 as the transfer path label setting process, and performs the path setting process based on the received message.

  17) An IP packet is input to the MPLS forwarding unit 120 of the receiving PE node 100.

  18) The MPLS transfer unit 120 searches the search table based on the label of the header of the IP packet, acquires the outgoing label (L2), and adds it to the header of the IP packet.

  19) The MPLS transfer unit 120 transfers the IP packet to which the outgoing label (L2) is added to the MPLS transfer unit 220 of the relay PE node 200.

  20) When the MPLS transfer unit 220 of the relay PE node 200 receives the IP packet to which the label (L2) transferred from the receiving PE node 100 is added, the MPLS transfer unit 220 searches the search table with the label (L2) and uses it as an outgoing label. (L1, L0) is acquired, IP packets and labels are copied, and labels (L1) and (L0) are added to the respective IP packets.

  21) The MPLS transfer unit 220 of the relay PE node 200 transfers the IP packet to which the label (L1) is added to the receiving PE node 300, and the IP packet to which the label (L0) is added corresponds to the label (L0). Forward to the receiving PE node.

  22) The MPLS transfer unit 320 of the receiving PE node 300 searches the search table based on the incoming label (L1) of the received IP packet, and deletes the outgoing label because the node is a leaf node.

  23) The MPLS transfer unit 320 transfers the IP packet when there is a downstream node branched from the reception PE node 300.

  Note that the search table of the MPLS transfer unit in each node is assumed to have a table search function and a switching function common to each node.

  Next, communication path setting update operation of multicast label switching will be described.

  FIG. 7 shows P2MP state information and leaf state information set in the P2MP protocol in one embodiment of the present invention.

  As shown in the figure, a common P2MP state is registered in all the PE nodes on the route, and leaf state information for the leaves accommodated by itself is registered in the downstream branch PE node. At this time, the path state information that is refresh-maintained in each PE node is processed based on a change in the common P2MP state.

  When there is no change in the P2MP state identifier (state ID information), it is processed as a refresh message, and when there is a change, it is processed as a trigger message. That is, if the number is increased by +1, the newly transmitted message corresponds to a state different from the old message and is transmitted as a trigger message.

  FIG. 8 is a diagram for explaining P2MP setting / addition processing using the P2MP protocol according to the embodiment of the present invention. In the example shown in the figure, first, leaf #D is set first, then leaf #E is set, and then leaves #G and #H are additionally set simultaneously. As shown in the figure, when additional settings are made, the P2MP state information common to the path message and the leaf state information to be added are stored and sent to the corresponding receiving leaf node, so that stepwise on the route P2MP LSP can be set in

  As a result, the reception leaf node sets a P2MP LSP corresponding to the path message, and transmits a path setting response (reception message) to the preceding PE node.

  FIG. 9 is a diagram for explaining a P2MP LSP deletion process using the P2MP protocol according to an embodiment of the present invention. In the example shown in the figure, first, an example is shown in which leaves #G and #H are simultaneously deleted, then leaf #D is deleted, and then leaf #E is deleted. As shown in the figure, even when deleting, the P2MP state information common to the Path Tear message and the leaf state information to be deleted are stored and sent to the corresponding receiving leaf. The P2MP LSP can be deleted step by step.

  FIG. 10 is a diagram showing refresh of the P2MP state in the embodiment of the present invention, and shows state maintenance using the P2MP protocol.

  The common P2MP state information and the corresponding leaf state information are exchanged between the PE nodes. At this time, if there is no change in the P2MP state ID in the sender template representing the P2MP state, the path message represents refresh. Furthermore, although the P2MP state ID is the same and the path message and the path tier message to which a leaf ID is newly assigned are processed as trigger messages, the refresh of the entire path state is not affected.

  By performing the above process, the MPLS signaling protocol of RSVP-TE can be expanded to copy P2MP traffic at the optimal branch point in the provider network, and the optimal P2MP traffic can be copied throughout the network. P2MP MPLS communication can be performed.

  For example, if you want to minimize the network cost of configuring a multicast distribution path to reduce costs, execute the algorithm to calculate the minimum tree, calculate the transfer path, and explicitly specify the calculated transfer path for multicast distribution It becomes feasible to set a route.

  Specifically, in an area such as a subway, when the broadcast server is at station A and multicast distribution is performed to station B, D, E, etc., and the relay PE node at station C is excellent in multicast function, The C station can be explicitly designated as a branch point. Here, the above-mentioned optimal branch point refers to station C.

  In addition, each operation of the above-mentioned transmission PE node, relay PE node, and reception leaf node can be constructed as a program and installed in a computer used as each node for execution or distributed via a network. is there.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

  The present invention is applicable to MPLS communication technology.

It is a figure for demonstrating the principle of this invention. It is a principle block diagram of this invention. It is a figure which shows the structure of each PE node in one embodiment of this invention. It is the operation example (the 1) in one embodiment of this invention. It is an operation example (the 2) in one embodiment of this invention. It is an operation example (the 3) in one embodiment of this invention. It is a figure which shows the P2MP state information and leaf state information which are set with the P2MP protocol in one embodiment of this invention. It is a figure for demonstrating the P2MP setting and addition process using the P2MP protocol in one embodiment of this invention. It is a figure for demonstrating the deletion process of P2MPLSP using the P2MP protocol in one embodiment of this invention. It is a figure which shows refresh of the P2MP state in one embodiment of this invention.

Explanation of symbols

1 Transmission PE node 2 Relay PE node 3 Reception PE node (Reception leaf node)
10 MPLS transfer route setting means 11 P2MP session object definition means 12 Sender template object definition means 13 Leaf object definition means 14 Path message generation means 15 Path message transmission means 21 Message transfer means 22 P2MP label switching route setting means 100 Transmission PE node 110, 210, 310 Protocol processing unit 111, 211, 311 Paste processing unit 112, 212, 312 Reserved state processing unit 120, 220, 320 MPLS forwarding unit #A Transmission PE node #B, #C, #F Relay PE node #D, #E, #G, #H Reception PE node (Reception leaf node)

Claims (12)

In a multiprotocol label switching (MPLS) communication network, a provider edge (PE) node located at the boundary of the MPLS network places point-to-multipoint (P2MP) communication traffic, including IP multicast traffic, at the multiple boundaries. In the point-to-multipoint MPLS communication method for transferring MPLS to the PE node,
The sending PE node
Up to multiple receiving PE nodes (hereinafter referred to as receiving leaf nodes), copy points are set up at multiple relay PE nodes in the PE using the MPLS signaling protocol, and a P2MP tree-shaped label switching path (LSP) is established. An MPLS transfer route setting step for setting an MPLS transfer route by setting it in the MPLS table as a storage means;
Based on the information of the MPLS table set in the MPLS transfer route setting step, performs an MPLS packet transfer step of transferring an MPLS packet, and
The MPLS transfer route setting step includes:
In setting the P2MP tree-shaped LSP in the transmission PE node,
P2MP LSP logical P2MP destination group address, tunnel identifier, and P2MP LSP logical P2MP destination group address, based on MPLS protocol that can guarantee QoS (Quality of Service) and traffic engineering (TE) A P2MP session object definition step for defining a P2MP session object configured with an extended P2MP tunnel identifier in a signaling protocol;
Further, in order to identify and manage a P2MP sender template, a P2MP LSP transmission address and a P2MP LSP identifier are added to the sender template information, and a P2MP state identifier representing the P2MP path state state is added to the sender template. A sender template object definition step for defining a sender template object by additionally defining information,
Furthermore, in order to identify and manage the state of a single receiving leaf node that constitutes the P2MP, a receiving address to be a receiving leaf node is defined, and partial P2P path information from the transmitting node to the receiving leaf node is defined. A leaf object definition step for defining a leaf object by defining a leaf state identifier for identification and management;
Path message generation for storing the P2MP session object defined in the P2MP session object definition step, the sender template object defined in the sender template object definition step, and the leaf object defined in the leaf object definition step in a path message Steps,
A path message transmission step of transmitting the path message from the transmission PE node to each reception leaf node of the P2MP LSP to be set;
In the relay PE node and the receiving leaf node that received the path message,
The P2MP label switching path between the transmitting node and the receiving node is set on the MPLS table by returning the received path message storing the P2MP session object, the sender template object, and the leaf object to the upstream node. P2MP label switching path setting step,
A point-to-multipoint MPLS communication method comprising a forwarding step of forwarding an MPLS packet based on information in the MPLS table set in the P2MP label switching path setting step. In the path message generation step,
The sending PE node stores P2MP session and sender template information in the path message as P2MP path state information for all nodes on the set P2MP LSP path,
In the P2MP label switching path setting step,
Each node on the set P2MP LSP path sets leaf state information corresponding to a reception leaf node accommodated downstream of each node in the path message as lower information of the P2MP session and the sender template information. Item 2. A point-to-multipoint MPLS communication method. When setting up a point-to-multipoint MPLS path,
The sending PE node is
A step of adding leaf state information corresponding to path information from the transmission PE node to a single reception leaf node to the P2MP session information and the sender template information, storing it in the path message, and transmitting the information to the reception leaf node And
The receiving leaf node is
Performing a step of setting a P2MP LSP of a P2MP portion corresponding to the path message by sending a received message for the path message to an upstream node;
The sending PE node is
A plurality of leaf state information corresponding to a plurality of route information from the transmitting PE node to a plurality of receiving leaf nodes is added to the P2MP session information and the sender template information, stored in the path message, and a plurality of the Perform partial P2MP LSP setup / update steps to send to the receiving leaf node,
The P2MP LSP setting / updating step includes:
When setting a new partial P2MP LSP,
A new setting step for newly setting state information in a node on the path is performed by assigning a new ID to the P2MP state identifier and a new ID to the leaf state identifier.
When adding a partial P2MP LSP to the configured partial P2MP LSP,
A sender template object with a P2MP state identifier that has the same state ID as the P2MP LSP state information that has already been set, and a leaf object that has a leaf state ID corresponding to the leaf LSP to be additionally set are stored in a path message and transmitted. By doing this, the additional setting step to perform additional setting of partial P2MP LSP in the same state is performed,
When deleting a partial P2MP route that reaches a single receiving leaf node of a configured partial P2MP LSP,
P2MP LSP stores leaf information corresponding to P2MP session information and sender template information in a Path Tear message and transmits only the corresponding lower leaf state information by transmitting from the transmitting PE node to the receiving leaf node to be deleted. 2. The point-to-multipoint MPLS communication method according to claim 1, wherein a deletion step of deleting the corresponding P2P route is performed. The deletion step includes
When deleting partial P2MP routes that reach multiple receiving leaf nodes of the configured P2MP LSP,
The P2MP session information and a plurality of leaf information corresponding to the sender template information are stored in the pastier message, and only the corresponding lower leaf state information is transmitted from the transmitting PE node to the plurality of receiving leaf nodes. Delete from the set P2MP LSP to delete the corresponding multiple P2P routes,
When deleting a receiving leaf node from the configured P2MP LSP,
Sender template information having the same state ID as the P2MP state identifier of the set P2MP LSP and leaf information having the same leaf identifier as the leaf state ID corresponding to the already set received leaf state are transferred to the past tier. 4. The point-to-multipoint MPLS communication method according to claim 3, wherein partial P2MP LSPs that are not in the same state are deleted by storing in a message. After completion of the P2MP LSP setting / updating step,
In the sending PE node,
A sender template having a state ID obtained by incrementing the P2MP state ID representing the state of the entire P2MP state, partial additional information such as route information, and path related information reflecting the partial deletion information is stored in the path message as a refresh message. Perform steps to notify downstream nodes,
The downstream node is
Detects a change in the state ID, detects that the path message is sent downstream as a trigger message for the purpose of state matching, and triggers the path message to a corresponding downstream path As a step to send immediately to the downstream node,
Each downstream node that receives the trigger message
The point-to-multipoint MPLS communication method according to claim 4, wherein the step of independently repeating a refresh cycle is performed based on the state ID of the trigger message. Each node on the P2MP path is
6. The point-to-multipoint MPLS according to claim 5, wherein when the path state is refreshed, even if there is a difference in leaf information included in a path message having the same P2MP state ID, the message is processed as a message for refreshing the same state. Communication method. In a multiprotocol label switching (MPLS) communication network, a provider edge (PE) node located at the boundary of the MPLS network places point-to-multipoint (P2MP) communication traffic, including IP multicast traffic, at the multiple boundaries. A point-to-multipoint MPLS communication system having a transmission PE node, a relay PE node, and a reception PE node, which performs MPLS transfer to the PE node,
The sending PE node is
By setting up a copy point at multiple relay PE nodes in the PE using the MPLS signaling protocol and setting up a P2MP tree-shaped label switching path (LSP) up to the plurality of receiving PE nodes, the MPLS transfer path MPLS transfer route setting means for setting
MPLS packet transfer means for transferring an MPLS packet based on the information in the MPLS table set in the MPLS transfer path setting step,
The MPLS transfer path setting means of the transmitting PE node is
When setting the P2MP tree-shaped LSP,
P2MP LSP logical P2MP destination group address, tunnel identifier, and extended P2MP tunnel identifier to identify and manage P2MP sessions based on MPLS protocol that can guarantee QoS and traffic engineering (TE) A P2MP session object defining means for defining a P2MP session object to be made in a signaling protocol;
Further, in order to identify and manage a P2MP sender template, a P2MP LSP transmission address and a P2MP LSP identifier are added to the sender template information, and a P2MP state identifier representing the P2MP path state state is added to the sender template information. A sender template object defining means for defining a sender template object by additionally defining;
Furthermore, in order to identify and manage the state of a single receiving leaf node that constitutes the P2MP, a receiving address to be a receiving leaf node is defined, and partial P2P path information from the transmitting node to the receiving leaf node is defined. Leaf object defining means for defining leaf state identifiers for identification and management;
Path message generation for storing the P2MP session object defined by the P2MP session object defining means, the sender template object defined by the sender template object defining means, and the leaf object defined by the leaf object defining means in a path message Means,
A path message transmitting means for transmitting the path message from the transmitting PE node to each receiving node of the P2MP LSP to be set;
The relay PE node on the LSP path on the P2MP tree set by the sending PE node is
Message transfer means for transferring a message transmitted from the transmitting PE node or an upstream node to a downstream node;
The received P2MP session object, the sender template object, and the path message in which the leaf object is stored are returned to the upstream node, whereby the P2MP LSP path between the transmitting node and the receiving node is displayed on the MPLS table. P2MP label switching route setting means to set,
Based on the information of the MPLS table set by the P2MP label switching path setting means, transfer means for transferring an MPLS packet,
A point-to-multipoint MPLS communication system. The path message generating means of the transmitting PE node is
As P2MP path state information for all nodes on the set P2MP LSP path, including means for storing P2MP session, sender template information in the path message,
The P2MP label switching path setting means of the relay PE node is
The point-to-multipoint MPLS according to claim 7, further comprising means for setting leaf state information corresponding to a reception leaf node accommodated downstream of each node in the path message as lower information of the P2MP session and the sender template information. Communications system. The sending PE node is
When setting up a point-to-multipoint MPLS path,
Means for adding the leaf state information corresponding to the path information from the transmission PE node to the single reception leaf node to the P2MP session information and the sender template information, storing it in the path message, and transmitting it to the reception leaf node Have
Each relay PE node is
A plurality of leaf state information corresponding to a plurality of route information from the transmitting PE node to a plurality of receiving leaf nodes is added to the P2MP session information and the sender template information, stored in the path message, and a plurality of the Means for transmitting to the receiving leaf node;
The plurality of receiving leaf nodes are:
Means for setting a P2MP LSP of a plurality of P2P parts corresponding to the path message by transmitting a received message for the path message to an upstream node;
The sending PE node means is:
When newly setting a partial P2MP LSP, a new setting means for newly setting state information in a node on the path by assigning a new ID to the P2MP state identifier and a new ID to the leaf state identifier;
When a partial P2MP LSP is additionally set to the set partial P2MP LSP, a sender template object having a P2MP state identifier having the same state ID as the state information of the already set P2MP LSP is added to the leaf LSP to be additionally set. An additional setting means for performing additional setting of a partial P2MP LSP in the same state by storing and transmitting a leaf object having a corresponding leaf state ID in a path message;
When deleting a partial P2MP route that reaches a single receiving leaf node of a set partial P2MP LSP, the leaf information corresponding to the P2MP session information and the sender template information is stored in a Path Tear message and transmitted. The point-to-multi point according to claim 8, further comprising: deletion means for deleting only the corresponding lower leaf state information from the PE node to the reception leaf node to be deleted, and deleting the corresponding P2P path by deleting only the corresponding lower leaf state information from the set P2MP LSP. Point MPLS communication system. The deleting means is
When deleting a partial P2MP path that reaches a plurality of receiving leaf nodes of the set P2MP LSP, the P2MP session information and a plurality of leaf information corresponding to the sender template information are stored in the pastier message, Means for deleting a plurality of corresponding P2P paths by deleting from the P2MP LSP in which only the corresponding lower-level leaf state information is transmitted from the transmitting PE node to a plurality of receiving leaf nodes; and
When deleting a reception leaf node from the set P2MP LSP, it corresponds to the sender template information having the same state ID as the P2MP state identifier of the set P2MP LSP and the reception leaf state already set. The point-to-multipoint MPLS communication system according to claim 9, further comprising means for deleting a partial P2MP LSP that is not in the same state by storing leaf information having the same leaf identifier as a leaf state ID in the pastier message. The sending PE node is
After the P2MP LSP setting / updating step is completed, a sender template having a state ID obtained by incrementing the P2MP state ID indicating the state of the entire P2MP state, a path addition reflecting partial addition information such as route information, and partial deletion information Means for storing information in a path message as a refresh message and notifying downstream nodes;
The relay PE node is
Detects a change in the state ID, detects that the path message is sent downstream for the purpose of state matching as a trigger message, and triggers the path message to a corresponding downstream path A means to immediately send it as a message to a downstream node;
Each downstream node that receives the trigger message
The point-to-multipoint MPLS communication system according to claim 10, further comprising means for independently repeating a refresh cycle based on a state ID of the trigger message. The relay PE node is
12. The point-to-point according to claim 11, further comprising means for processing the same state as a message for refreshing even if there is a difference in leaf information included in the path message having the same P2MP state ID when the path state is refreshed. Multipoint MPLS communication system.

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