Point to multi-point mpls communication method

The present invention relates to a point-to-multipoint MPLS communication method, and in particular, MPLS (Quality of Service) guarantees MPLS (Quality of Service) while efficiently TE (Traffic Engineering) traffic for P2MP communication in MPLS transfer technology. The present invention relates to an MPLS communication protocol technology for setting a point-to-multipoint MPLS transfer path and a point-to-multipoint MPLS communication method for the systematization technology of the multipoint MPLS technology for transfer.

As an MPLS (multiprotocol label switching) signaling protocol, there is RSVP (Resource ReSerVation Protocol) -TE, and there is an MPLS signaling protocol that sets the LSP of P2P (see, for example, Non-Patent Document 1).<nplcit num="1"><text>RSVP-TE: Extensions to RSVP for LSP Tunnels, RFC3209, IETF</text></nplcit>

<p> However, RSVP-TE is an MPLS signaling protocol that sets a P2P (point-to-point) LSP (label switching path), so when trying to transfer a P2MP (point-to-multipoint) communication traffic, the transmitting PE (provider) Set multiple P2P LSPs up to multiple receiving PE nodes that are the destinations of P2MP communication on the edge) node, copy the receiving traffic on the transmitting PE node, copy it to multiple set P2P LSPs, and replace it. Since there is a need, there is a problem that the copy performance at the transmitting PE node is squeezed and the transfer efficiency of the network is lowered.</p><p> The present invention has been made in view of the above points, and extends RSVP-TE's MPLS signaling protocol so that P2MP traffic can be copied at the optimum branch point in the provider network, and the optimum copy of P2MP traffic can be copied for the entire network. The purpose is to provide a point-to-multipoint MPLS communication method that enables.</p>

<p> In the present invention, in a Multiprotocol Label Switching (MPLS) communication network, a provider edge (PE) node located at the boundary of an MPLS network arranges a plurality of point-to-multipoint (P2MP) communication traffic including IP multicast traffic at the boundary. In a point-to-multipoint MPLS communication method in which MPLS is transferred to the provided provider edge (PE) node, the transmitting PE node copies to multiple relay nodes in the provider edge using the MPLS signaling protocol up to multiple receiving PE nodes. When setting the MPLS transfer path by setting the P2MP tree-shaped label switching path (LSP) and setting the P2MP tree-shaped label switching path (P2MP LSP), multiprotocol Based on the Label Switching (MPLS) protocol RSVP-TE (RFC3209), P2MP is used to identify P2MP sessions in P2MP traffic. A P2MP session object consisting of the sending PE address and tunnel identifier of the LSP, and a P2MP tunnel identifier and sequence number as an extension of the tunnel identifier is defined, and the PE node is set to specify the P2MP LSP shape. The tree-like route from the transmitting PE of the target P2MP LSP to multiple receiving leaf PE nodes was decomposed by the point-to-point (P2P) MPLS transfer route from the transmitting PE node to each receiving PE node. , The P2P route is specified by the ERO object, which is the P2P transfer route instruction object defined by RSVP-TE (RFC3209), and when the P2MP LSP is set, the transmitting PE node indicates the P2MP LSP route from the outside. Or, when the P2MP LSP route to be set is grasped by performing the P2MP LSP route calculation to be set between the transmitting PE and multiple receiving PE nodes in cooperation with the traffic engineering extension function of the internal IP routing protocol. In addition, the tree path is converted into a P2MP LSP setting path by means of decomposing it into a P2P path. The sending PE node is a sequence that specifies the common header as a path message when setting P2MP LSP, P2MP_LSP_id that specifies the P2MP tree to be set in the defined P2MP session object, and the sending numbers of multiple messages required for that tree format. A path message containing the RSVP_HOP object, TIME_VALUES object, ERO object that specifies the decomposed first P2P route, LABEL_REQUEST object, SENDER object, SENDER_TEMPLATE object, and SENDER_TSPEC object should be set from the sending PE node by specifying the number as 0. Performs the process of sending to the nearest downstream node that composes the P2MP LSP, The sending PE node specifies the second P2P route when the P2MP tree-like route to be set is set by multiple P2P routes and there are multiple P2P routes other than the first P2P route. Prepare an ERO, specify a common header as a path message, P2MP_LSP_id that specifies the P2MP tree to be set in the defined P2MP session object, and the sequence number required for that tree format to 1, RSVP_HOP object, TIME_VALUES object. , Sends a path message containing the ERO object, LABEL_REQUEST object, SENDER_TEMPLATE object, and SENDER_TSPEC object that specifies the decomposed second P2P route from the sending PE node to the nearest downstream node that composes the P2MP LSP that should be set. Do, The sending PE node repeats the above procedure up to the final P2P route that constitutes the P2MP tree-like route, prepares an ERO that specifies the final P2P route, and uses the common header as the path message and the defined P2MP session object. Set the End specification bit to P2MP_LSP_id that specifies the P2MP tree to be set and the sequence number required to form the tree (repetition number-1), and specify that the path message is the final path message. A path containing RSVP_HOP object, TIME_VALUES object, ERO object that specifies the final decomposed P2P route, LABEL_REQUEST object, SENDER_TEMPLATE object, and SENDER_TSPEC object. The downstream node that received the pass message after performing the process of sending to The registered Path state information is searched, and if the path message is a new received path message, session information is extracted from the path message, and if the path of the setting request can be set, it is newly added as Path state information. The ERO that should be set as a partial P2P route of P2MP LSP is extracted from the path message, and the downstream next hop address defined as the next hop of its own node address is extracted from the ERO information. When the upstream node sends out a plurality of path messages, the downstream node that performs the extraction process and receives the path message requests the P2MP LSP route setting for the P2MP session with the same path message from the received path message. It is determined that it is a message, and the partial P2P route of P2MP LSP to be set next is extracted as ERO from the ERO information stored in the path message, and the next hop of its own node address is extracted from the ERO information. Performs the process of extracting the downstream next hop address defined as Until the downstream node that receives the path message receives the path message with the End bit setting that indicates to the P2MP session object of the path message from the upstream that it is the path message for the final part P2P route setting of the P2MP setting route, the above When the process is repeated and the final path message with the End bit set is received, the process of retaining the path message, extracting the final P2P route as ERO, and at the same time specifying the next hop address is performed in the same manner as above. Further, the process of extracting the next hop information extracted from each ERO information, deleting its own node address from each ERO information, and shaping the ERO information so that the next hop address becomes the first stored information of each ERO information. Furthermore, when there are a plurality of common next hop address groups, a process of grouping ERO information having the same next hop address is performed, and after the above process, the downstream node corresponding to the next hop is said to be downstream. Re-grouped path messages destined for a node are sent to the part P2MP under the downstream node. Stores the reconstructed ERO information that specifies the LSP, assigns a sequence number to the same P2MP_LSP_id information above to the next hop node downstream, and sends the final path message with the End bit set. Processes, registers Path state information, regroups path messages, and repeats transfer to the next downstream node that specifies the sequence number for each group, and repeats the process to the receiving PE node, which is the most downstream leaf node. Repeat until is reached, registering the Path state with the node on the P2MP LSP path, and when all receiving leaf PE nodes receive the path message, the receiving leaf PE node knows that it is the leaf edge node of the P2MP LSP. If it is determined and the receiving node can set the requested P2MP LSP, after registering the "Resv state", the receiving node owns the label value used to transfer and receive the P2MP traffic from the upstream node. Assigned from the label space of the node, and P2MP In order to enable data forwarding in LSP, the process of registering the label exchange relationship in the ILM table and NHLFE table is performed, and the label value and LABEL object given upstream are RRO objects that show the P2MP LSP setting route information. Stores its own node address in the SESSION object, sets the P2MP_LSP_id identifier, sequence number 0 and End bit in the SESSION object, stores them, stores them in the Resv message, and stores the path message in the upstream PHOP node. When the PHOP object receives the Resv message for the first time, the PHOP node performs the process of immediately sending the Resv message to the RRO, which represents the transfer route record of the P2MP LSP set for the downstream node corresponding to the Resv message. Information, when transferring P2MP traffic to a downstream node, the process of registering the "Resv state" including the label value to be given to the packet is performed, and after registering the "Resv state", the PHOP node is connected to the further upstream PHOP node. The label value used to transfer and receive the P2MP traffic between them is given from the label space of the own node, and P2MP In order to enable P2MP data forwarding in the LSP, the process of registering the label exchange relationship in the ILM table and NHLFE table is performed, and the label value given upstream and the setting route information of the P2MP LSP are sent to the RRO with its own node address. Is added to the beginning, and P2MP_LSP_id and sequence number 0 indicating the first Resv message are added to the P2MP session object, and when multiple path messages have already been sent downstream of the node. If you are sending only a single path message to the downstream node without setting the End bit, set the End bit and store them in the Resv message to the upstream PHOP node. The process is immediately forwarded as a Resv message to, and the node has multiple downstream nodes, and the same P2MP to be set. When a Resv message other than the initial Resv message is received from a downstream node with a different LSP, the configured "Resv state" is searched for in the session information of the Resv message, and the corresponding downstream node corresponds to the already registered Resv state information. The node that received the Resv message after performing the process of additionally registering additional information including the RRO information that is the transfer route record of the P2MP LSP set for, is upstream of the P2MP LSP that should be set from the registered Resv state information. When it is determined that the LSP of the PHOP of is set, the process of identifying the MPLS label given upstream is performed, and the Resv route newly received for the target P2MP LSP is newly received. In order to enable MPLS forwarding of P2MP LSP, the label given upstream to the already set ILM table and NHLFE table is specified from the ILM table, and the Resv received in the NHLFE table which is the entry. Performs the process of newly registering the label value for downstream MPLS transfer specified from the message as a new entry. Furthermore, in order to record the MPLS label value used for the upstream PHOP extracted earlier and the setting tree information set under the relevant node, the corresponding tree-based RRO information set under the newly received route is applicable. By adding the node address information at the beginning, the newly set partial tree information is processed as RRO information, the processed RRO information is additionally registered in the Resv state information, and further set. The MPLS label value used for upstream label transfer is specified, the process is performed to store it in the Resv message together, and the state change of the tree in which the Resv message is set (new part P2MP LSP addition) is notified. In order to perform the process of instantly transferring to the upstream PHOP node and notifying the Resv message upstream, when notifying the setting information to the second and subsequent downstream nodes, the first Resv sent earlier Holds P2MP_LSP_id of P2MP session information of the message, increments the sequence number by 1, and performs the processing to notify. If the Resv message is the Resv message of the last P2MP route set downstream from the node, not only the sequence number is incremented by 1 but also the End bit is set when the Resv message is notified to the upstream PHOP. When the Resv message is received for the first time for the P2MP LSP to be set, the node that receives the Resv message performs the process of newly registering the Resv state information, and further upstream. Extract the MPLS label used for label transfer with PHOP from its own label space, and register a new label exchange relationship in the ILM table and NHLFE table of the forwarding part to enable MPLS label transfer. Furthermore, the label value used for label transfer with the upstream and its own node address are added to the route registration information RRO, and the label value and the corrected RRO information are stored in the Resv message and the upstream PHOP. Is processed to transfer instantly to Furthermore, if the receiving node has already received a Resv message from another downstream node and completed Resv processing to upstream Resv message transmission and set a partial P2MP LSP, the newly set P2MP LSP will be used. On the other hand, when a Resv message is received from another downstream route, the corresponding Resv state information is specified from the registered Resv state information, and the RRO information indicating the newly added downstream partial P2MP LSP route is added. Extracted by Resv message, correct the already set RRO information registered in Resv state information, make additional settings, and at the same time, identify the MPLS label attached to the upstream label transfer and add a new one. Stores the RRO corresponding to in the Resv message, and if this newly added part is the final route of the downstream route of the node, set the End bit of the P2MP session object and immediately transfer it to the upstream PHOP. Perform processing and repeat until the Resv message reaches the sending PE node on all nodes of the P2MP LSP for which the above processing should be set, and the sending PE node should be set for P2MP. When the Resv message is received for the first time for the LSP, the label value required for MPLS label transfer downstream from the Resv message is extracted, and at the same time, the set downstream route information RRO is extracted and used as the Resv state information. In order to perform the process of registering and to enable MPLS forwarding for the set P2MP LSP, the process of registering the label transfer relationship in the FTN table and NHLFE table of the incoming PE is performed, and the sending PE node is further processed. When receiving a Resv message for a P2MP LSP to be configured from a different downstream node, identifies the corresponding registered Resv state information and extracts the RRO information corresponding to the newly added downstream partial P2MP LSP. However, it is added and modified to the registered RRO information, processed and modified so that it becomes the set tree registration information at the current stage, and at the same time, it is newly added to the FTN table and NHLFE table to enable MPLS forwarding. The process of adding the label exchange relationship for the partial tree is performed, and the sending PE node is the P2MP set as the path message. For the LSP, when the P2MP label exchange relationship is set for all the nodes that make up the P2MP LSP, from the transmitting PE node to multiple receiving PE nodes using MPLS signaling, the received packet is set. According to P2MP LSP, label switching is performed from the transmitting PE node to multiple receiving PE nodes on a P2MP basis, and after the P2MP LSP is established, the "Path state" and "Resv state" between the nodes are periodically refreshed. By exchanging Path / Resv messages of, in periodic refresh, if there are multiple receiving leaf PE nodes under the downstream node between the upstream node and the downstream node, multiple paths for the receiving leaf PE node -In the exchange of Resv messages, the process of holding / exchanging the partial state of the P2MP LSP for which a single Path / Resv message is set is performed, and the End bit is set together with the Path / Resv message for the final information. By performing the process of exchanging the final state by, the process of executing the state maintenance is performed.</p><p> Further, according to the present invention, when a partial P2MP LSP is set to a P2MP LSP that has already been set in the transmitting PE node, a plurality of partial trees from the transmitting PE node constituting the partial tree to be added in the same manner as the initial tree setting information. Of the receive leaf PE node group of, the route is indicated by the ERO to the receive leaf PE node, and the {ERO} s set to the destination of the ERO which is the partial route of the additional P2MP LSP is the ERO (Graft) for partial addition. Use the same P2MP_LSP_id specified in the already set P2MP session object as information, and if there is multiple ERO information, specify it for the P2P route that constitutes the final subtree of the previously set P2MP LSP. The process of increasing the final sequence number by 1 and adding it to the path message containing the ERO information for the first partial addition, and sending the path message containing the modified P2MP session information and new ERO information. , While holding the P2MP_LSP_id of the P2MP session object, the path message containing the ERO information for partial addition is incremented by 1 and sent to the adjacent downstream node until the final ERO information for partial addition is reached. Furthermore, when it comes to the final ERO information, the process of sending the path message to the nearby downstream node by setting the End bit notifying that the path message is the final state element of the P2MP LSP is set in the final sequence number, and the path message is received. The path message is a new path message by detecting that the received path message contains a larger sequence number for P2MP_LSP_id held by the already received path message in the downstream proximity node. When specifying, the process of setting the P2MP LSP by immediately transferring only the newly received path message group to the downstream adjacent node according to the process of setting the P2MP LSP, and the process of setting the P2MP LSP and the node that received the path message. In If the received path message holds the same P2MP_LSP_id and has a sequence number less than or equal to the already set sequence number, the information content of the path message is compared with the registered Path state information and added to the information element. If there is no change, the process shifts to the maintenance state of the periodic path message, and if there is a change in the extracted session information, the path message is immediately sent to the route that should reflect the change in the session information. In the process of transferring and the leaf PE node that received the immediately transferred path message, labeling used for MPLS transfer with PHOP with the upstream, updating the "Resv state" of its own node, label exchange relation Performs an update process and an additional process consisting of the update.</p><p> Further, the present invention is a deletion target corresponding to the P2MP tree corresponding to the part to be deleted as the partial P2MP LSP from the already set route information {ERO} s set when the partial P2MP LSP is deleted from the already set P2MP. Processing to specify the route {ERO} s set, processing to newly extend / store the {ERO} s set corresponding to the partial P2MP LSP to be deleted in the PathTear message, and P2MP session information of the expanded / stored PathTear message. Holds P2MP_LSP_id, extracts the sequence number corresponding to the configured ERO information corresponding to the part P2PLSP to be deleted from the stored Path state information, stores it in the P2MP session information, and stores it in the PathTear message. Processing to be performed, processing to send a PathTear message to an adjacent downstream node that has a P2MP transfer route downstream to be deleted, processing to be sent by the PE node, and P2MP session information of the received PathTear message at the downstream node that received the path message. The part to be deleted P2MP stored in the set Path state information The process of identifying the P2MP LSP including the LSP and deleting the ERO information corresponding to the partial tree information to be deleted from the Path state information, and the ERO information included in the PathTear message at the node from which the corresponding ERO information has been deleted. The process of deleting the own node address information from and changing it to ERO information that newly specifies the route to be deleted in the downstream direction, and the PathTear message that has the same P2MP session information specified earlier in the changed ERO information. The process of re-storing and immediately transferring to the adjacent downstream node, the process of deleting the Path state information that constitutes the P2MP partial LSP to be deleted in the downstream node by sending the PathTear message, and the process of deleting the PathTear message. The process of reaching the receive leaf PE node of the partial P2MP LSP and the process of deleting the partial P2MP LSP to be deleted by reaching all the receive leaf PE nodes of the partial P2MP LSP to be deleted. And, the deletion process consisting of.</p><p> Further, according to the present invention, when a partial P2MP LSP is set to a P2MP LSP that has already been set in the transmitting PE node, a plurality of partial trees from the transmitting PE node constituting the partial tree to be added in the same manner as the initial tree setting information. Of the receive leaf PE node group of, the route is indicated by the ERO to the receive leaf PE node, and the set {ERO} s to the destination of the ERO which is the partial route of the additional P2MP LSP is ERO (Graft) for partial addition. Use the same P2MP_LSP_id specified in the already set P2MP session object as information, and if there is multiple ERO information, specify it for the P2P route that constitutes the final subtree of the previously set P2MP LSP. The process of incrementing the final sequence number by 1 and adding it to the path message containing the ERO information for the first partial addition, and sending the modified P2MP session information and the path message containing the new ERO information. When, While holding the P2MP_LSP_id of the P2MP session object, the path message containing the ERO information for partial addition is incremented by 1 and sent to the adjacent downstream node until the final ERO information for partial addition is reached. Furthermore, when it comes to the final ERO information, the process of sending the path message to the nearby downstream node by setting the End bit notifying that the path message is the final state element of the P2MP LSP is set in the final sequence number, and the path message is received. The path message is a new path message by detecting that the received path message contains a larger sequence number for P2MP_LSP_id held by the already received path message in the downstream proximity node. When specifying, the process of setting the P2MP LSP by immediately transferring only the newly received path message group to the downstream adjacent node according to the process of setting the P2MP LSP, and the process of setting the P2MP LSP and the node that received the path message. In If the received path message holds the same P2MP_LSP_id and has a sequence number less than or equal to the already set sequence number, the information content of the path message is compared with the registered Path state information and added to the information element. If there is no change, the process shifts to the maintenance state of the periodic path message, and if there is a change in the extracted session information, the path message is immediately sent to the route that should reflect the change in the session information. In the process of transferring and the leaf PE node that received the immediately transferred path message, labeling used for MPLS transfer with PHOP with the upstream, updating the "Resv state" of its own node, label exchange relation The part to be deleted as the partial P2MP LSP from the set route information {ERO} s set when the partial P2MP LSP is deleted from the already set P2MP and the additional process of the P2MP LSP consisting of the update process and the P2MP LSP. Process to specify the deletion target route {ERO} s set corresponding to the P2MP tree corresponding to, and the part P2MP to be deleted P2MP_LSP_id is retained in the process of newly expanding and storing the {ERO} s set corresponding to LSP in the PathTear message and the P2MP session information of the extendedly stored PathTear message, and the already set corresponding to the part P2PLSP to be deleted. The process of extracting the sequence number corresponding to the ERO information of the above from the stored Path state information, storing it in the P2MP session information, and storing it in the PathTear message, and the PathTear in the adjacent downstream node that has the P2MP transfer route to be deleted downstream. In the process of sending the message by the PE node and the downstream node that received the path message, the P2MP session information of the received PathTear message includes the part to be deleted P2MP LSP stored in the Path state information that has already been set. A process of identifying the P2MP LSP and deleting the ERO information corresponding to the partial tree information to be deleted from the session information. In the node where the corresponding ERO information has been deleted, the process of deleting the own node address information from the ERO information included in the PathTear message and changing it to the ERO information that newly specifies the route to be deleted in the downstream direction, and the changed ERO The P2MP part to be deleted in the downstream node by the process of re-storing the information in the PathTear message with the same P2MP session information specified earlier and immediately transferring it to the adjacent downstream node and sending the PathTear message. The process of deleting the Path state information that makes up the LSP, the process of causing the PathTear message to reach the receive leaf PE node of the part P2MP LSP to be deleted, and the process of making the multiple PathTear messages reach the receive leaf PE node of the part P2MP LSP to be deleted. By reaching the node, the process of deleting the partial P2MP LSP to be deleted and the process of deleting the P2MP LSP consisting of all are performed at the same time.</p><p> Further, in the present invention, when an intermediate node that has received a plurality of path messages identifies the next hop set information from the TERO information included in the plurality of path messages, the address information specified as Loose in the next hop information is used. If it is included, the process that enables the tree-based LSP extension of P2MP for the address group specified by Loose is performed.</p><p> As described above, the present invention specifies the P2MP session information that specifies the P2MP LSP to be set in the RSVP-TE path message when setting the multicast label switching route, and specifies the partial P2P route of the P2MP to be set. Describe the P2MP route you want to set in the {ERO} s set because multiple path messages holding ERO information are sent for the P2P routes that make up the P2MP route and the intermediate tree branch node sets the branch of the data plane. The main feature is that the transfer path of P2MP LSP can be easily set while setting a copy branch point in the network.</p><p> The conventional technology is that not only P2P LSP but also P2MP LSP can be set by traffic engineering by any transfer path using the same protocol. Not only P2MP but also P2MP and P2P LSP can be set at the same time. The points that can be done are very different.</p><p> Furthermore, since the tree-based routing information is composed of ERO, which is P2P MPLS routing information, the entire tree is sent from the transmitting PE to multiple receiving leaf PEs when specifying the tree shape of the P2MP LSP to be set. Since it can be specified as a superposition of routes, it enables intuitive route specification, and P2MP LSP can be set using the path message mechanism that holds ERO already implemented in existing P2P. , P2MP can be easily extended by using the existing P2P RSVP-TE implementation assets.</p>

<p> According to the present invention, it is possible to construct an MPLS transfer network capable of efficiently performing multicast transfer of P2MP traffic with high performance.</p>

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

[First Embodiment]

In this embodiment, a communication route setting method and a packet transfer mechanism for multicast label switching will be described.

FIG. 1 shows a P2MP session object according to the first embodiment of the present invention.

When setting the LSP of P2MP, use the tunnel identifier and the sender address of the tunnel as the P2MP session. Figure 1 shows an IPv4 P2MP session object. Also, as shown in Figure 1, the P2MP session object contains P2MPTunnel ID information, which is required to identify the P2MP LSP, and a sequence ID, which enables different Path / Resv message operations for the same P2MP LSP. It also contains an End bit that specifies the final operation of the Path / Resv message.

FIG. 2 is an example of a P2MP LSP according to the first embodiment of the present invention. The figure shows an example of a P2MP transfer path from the transmitting PE node A to the four receiving PE leaf nodes G, F, C, and D. This TERO information can be expressed as a superposition of different P2P transfer paths. For example, in the case of FIG. 2, the transfer route from the transmitting PE node A to the receiving PE leaf node G is P2P route 1: {A, B, E, G}, and similarly, the receiving PE leaf node from the transmitting PE node A. The transfer route to F is P2P route 2: {A, B, E, F}, and the transfer route from the transmitting PE node A to the receiving PE leaf node D is P2P route 3: {A, B, D}. Similarly, the transfer route from the transmission PE node A to the reception PE leaf node C can be represented by P2P route 4: {A, B, C}. Therefore, since the tree-based transfer route information TERO, which is the P2MP transfer route in FIG. 2, can be expressed as a set of EROs, which are P2P transfer route information, {ERO} s = {ERO1 (A, B, E, G). , ERO2 (A, B, D), ERO4 (A, B, C)}.

Next, the path message and the Resv message used in the present invention will be described. The path message is &lt;Path Message&gt; :: &lt;Common Header&gt; [&lt;INTEGRITY&gt;]

[[&lt;MESSAAGE_ID_ACK&gt; &lt;MESSAGE_ID_NACK&gt;] ...]

[&lt;MESSAGE_ID&gt;] &lt;P2MP_SESSION&gt; &lt;RSVP_HOP&gt; &lt;TIME_VALUES&gt; &lt;EXPLICIT_ROUTE&gt; &lt;LABEL_REQUEST&gt; [&lt;PROTECTION&gt;]

[&lt;LABEL_SET&gt;] [&lt;SESSION_ATTRIBUTE&gt;]

[&lt;NOTIFY_REQUEST&gt;] [&lt;ADMIN_STATUS&gt;]

[&lt;POLICY_DATA&gt; ...] &lt;sender descriptor&gt; &lt;sender descriptor&gt; :: = &lt;SENDER_TEMPLATE&gt; Expressed in &lt;SENDER_TSPEC&gt; format. The major difference from the conventional P2P RSVP-TE is that the P2MP SESSION object format is defined to enable the operation of P2MP LSP as described above. Also, the Resv message is &lt;Resv Message&gt; :: = &lt;Common Header&gt; [&lt;INTEGRITY&gt;]

[[&lt;MESSAGE_ID_ACK&gt; &lt;MESSAGE_ID_NACK&gt;] ...]

[&lt;MESSAGE_ID&gt;] &lt;P2MP_SESSION&gt; &lt;RSVP_HOP&gt; &lt;TIME_VALUES&gt; [&lt;RSVP_CONFIRM&gt;] [&lt;SCOPE&gt;]

[&lt;NOTIFY_REQUEST&gt;] [&lt;ADMIN_STATUS&gt;]

[&lt;POLICY_DATA&gt; ...] &lt;STYLE&gt; &lt;flow descriptor list&gt; &lt;flow descriptor list&gt; :: = &lt;FF flow descriptor list&gt; &lt;SE flow descriptor&gt; &lt;FF flow descriptor list&gt; :: = &lt;FLOWSPEC&gt; &lt;FILTER_SPEC &gt; &lt;LABEL&gt; [&lt;RECORD_ROUTE&gt;]

&lt;FF flow descriptor list&gt; &lt;FF flow descriptor&gt; &lt;FF flow descriptor&gt; :: = [&lt;FLOWSPEC&gt;] &lt;FILTER_SPEC&gt; &lt;LABEL&gt; [&lt;RECORD_ROUTE&gt;]

&lt;SE flow descriptor&gt; :: = &lt;FLOWSPEC&gt; &lt;SE filter spec list&gt; &lt;SE filter spec list&gt; :: = &lt;SE filter spec&gt; &lt;SE filter spec list&gt; &lt;SE filter spec&gt; &lt;SE filter spec&gt; :: = &lt;FILTER_SPEC&gt; &lt;LABEL&gt; [&lt;TREE_RECORD_ROUTE&gt;]

It is expressed in the format of. The major difference from the conventional P2P RSVP-TE is that the P2MPSESSION object is different.

Next, the basic setting mechanism of the P2MP LSP will be described with reference to FIGS.

Figure 2 shows an example of setting P2MP LSPs up to C, D, F, and G where the transmitting PE node is the receiving PE leaf node.

The P2MP LSP route to be set follows the transfer route shown in Fig. 2. When the transmission PE node A determines the transfer route of the P2MP LSP to be set, it manages the transfer route information as a set of transfer route information {ERO} s.

In this example, {ERO} s = {ERO (A, B, C), ERO (A, B, D), ERO (A, B, E, F), ERO (A, B, E, G)} It has become. In addition, the sending PE node stores the P2MP LSP Session ID to be set and the P2MPTunnel ID in the P2MP SESSION object. At the same time, specify the LSPID with SENDER TEMPLATE. After this, the sending PE node A specifies the Common Header in the path message and the Tunnel ID and P2MP Tunnel ID in the P2MP SESSION, and at the same time, the P2P route starting from the {ERO} s set that constitutes the tree information of the P2MP LSP to be set. Specify the information ERO (A, B, C), set the sequence number 0 (initial value) of P2MP SESSION for that information, and do not specify the End bit. Furthermore, RSVP-HOP, TIME_VALUE, ERO (B, C) specified earlier, LABEL_REQUEST, SENDER_TSPEC, and RECORD_ROUTE objects are stored in the path message and transferred to the downstream node B.

At this time, the transmitting PE node A further identifies the ERO (A, B, D), which is the second part P2P route of the P2MP LSP to be set, and sets the common header in the path message and the Tunnel ID in the P2MP SESSION. Set the sequence number 1 (increment) of P2MP SESSION for the partial path ERO (A, B, C) of P2MP LSP that should be set at the same time as specifying the P2MP Tunnel ID, and do not specify the End bit. Furthermore, RSVP_HOP, TIME_VALUE, ERO (B, D) specified earlier, LABEL_REQUEST, SENDER_TEMPULATE, SENDER_TSPEC, and RECORD_ROUTE objects are stored in the path message and sent to the downstream node B.

At this time, the transmitting PE node A further identifies the ERO (A, B, E, F), which is the P2P route of the third part of the P2MP LSP to be set, and sets the path message to Common Header and P2MP SESSION to Tunnel. At the same time as specifying the ID and P2MP Tunnel ID, set the sequence number 2 (increment) of P2MPSESSION for the partial path ERO (A, B, E, F) of P2MP LSP to be set, and do not specify the End bit. Furthermore, RSVP_HOP, TIME_VALUE, ERO (B, E, F) specified earlier, LABEL_REQUEST, SENDER_TEMPULATE, SENDER_TSPEC, and RECORD_ROUTE objects are stored in the path message and sent to the downstream node B.

At this time, the transmitting PE node A further identifies the ERO (A, B, E, G), which is the fourth (last) partial P2P route of the P2MP LSP to be set, and sets the common header in the path message. Specify the Tunnel ID and P2MP Tunnel ID for P2MPSESSION, and at the same time, set the sequence number 3 (increment) of P2MPSESSION for the partial path ERO (A, B, E, G) of P2MP LSP to be set, and this part. Since the route is the last part P2P route that composes the P2MP LSP to be set, specify the End bit, RSVP_HOP, TIME_VALUE, ERO (B, E, G) specified earlier, LABEL_REQUEST, SENDER_TEMPULATE, SENDER_TSPEC. , Store the RECORD_RUTE object in the path message and send it to downstream node B.

Upon receiving the path message, the node B searches the path state information from the storage means and determines that the P2MP session is a new P2MP session (the first path message including the above-mentioned ERO (B, C)). If the P2MP LSP of the path setting request can be set for the node, information is registered as session information in the Path state as SESSION, RSVP_HOP, LABEL_REQUEST, SENDER_TEMPLATE, and RECORD_ROUTE objects. ..

In the example of FIG. 2, the node B then receives the path message of the second ERO (B, D) path, Seq = 1. Since the node B can identify from the P2MP session information that the message is for the P2MP LSP in the path state that has already received the path message and is registered in the path state of the storage means of the node B, it can be stored. When the Path state information registered in the means is searched and the registered information is determined to be configurable by the P2MP LSP for which the setting is requested, the newly set information, ERO (B, D) ) Is registered in the corresponding Path state information.

At this time, in the example of FIG. 2, after that, the node B receives the third ERO (B, E, F) path, the path message of Seq = 2. The node B can be registered because the P2MP session information can identify that the path message is a message for the P2MP LSP in the Path state that has already been received and registered in the Path state of the storage means of the node. When the registered Path state information is searched and it is determined that the registered information and the P2MP LSP for which the setting is requested can be set, the newly set information ERO (B, E, F) is displayed. Register in the corresponding Path state information.

At this time, further, in the example of FIG. 2, the node B then receives the fourth (last) ERO (B, E, G) path, seq = 3 path message. It is determined that this path message is the final message of the setting request by setting the End bit of the P2MP session information included in the path message. The node is registered in the storage means because it can be identified from the P2MP session information that the path message is a message for the P2MP LSP in the Path state that has already been received and registered in the Path state of the node. If it is determined that the registered information and the P2MP LSP for which the setting is requested can be set, the newly set information and ERO (B, E, G) are displayed. Register in the corresponding Path state information.

After this, the node B should be set from the Path state information registered in the storage means, P2MP. Determines what the pass message must be sent to the LSP as the next hop. First, the Path state information is searched, the next hop: E is specified from ERO (B, C, F) for the P2MP_LSP_id to be set, and then the next hop from ERO (B, E, G). Identify E :. Based on this determination, the node B determines that a single path message should be sent to the next hops C and D, so ERO (C) and ERO (D) are specified, respectively, and new Sequence number: 0, specify the End bit, which is the last path message, in the P2MP session object and immediately send the path message to the downstream nodes, C, and E. At this time, since it is determined by the previous determination that two path messages must be sent to the leaves E and G for the downstream node E, in this example, first, the node F is used. Specify ERO (E, F) for, sequence number: 0, specify P2MP session information without specifying the End bit, store it in the path message, send it immediately, and then send it to node G. Specify ERO (E, G), specify the sequence number: 1 (increment) End bit, store the P2MP session information in the path message, and send it immediately.

After receiving the second pass message, node E registers the Path state information in the storage means by the mechanism described above after receiving the second pass message, and further, the path message is directed to the downstream nodes F and G. Is sent.

Figure 3 shows the operation mechanism of each leaf that received the path message. Each receiving leaf node receives the path message, registers the Path state, and if the LSP can be reserved and confirmed in response to the path setting request, the Resv state is registered in the node and at the same time upstream. Immediately send a Resv message back to the upstream PHOP with the label value used for the transfer to and from the PHOP. At this time, in each node, the internal forwarding plane is set at the same time, the ILM table and the HNLFE table are set in the storage means, and the forwarding relationship for the MPLS label notified upstream is set.

In addition, the example of FIG. 3 shows an example in which nodes C, D, F, and G are sending a Resv message. At this time, the same P2MP_LSP_id is set in the P2MP session object, and the sequence number is Seq = 0 because the LSP from the leaf is confirmed by receiving one Resv message, so this is the last Resv message. The End bit is set to notify. In the example of FIG. 3, first, node B receives two Resv messages from leaves C and D.

First of all, node B receives the Resv message from leaf C, registers the Resv state in the storage means, and at the same time, assigns a label value to be used with the upstream, and at the same time, establishes a label exchange relationship. Register the label notified upstream in the ILM table and the label value notified from the downstream in the NHLFE table to establish, and build a label exchange relationship. At the same time as this operation, the RRO object is updated to notify the confirmation of the BC route, and the label and RRO information are immediately stored in the Resv message and notified upstream. At this time, node B has a P2MP for which the Resv message has a setting request according to the previous path message. Since it is determined that this is not the last Resv message for the LSP, P2MP session information with Seq = 0 and the End bit not specified is registered in the Resv message. Furthermore, similarly, when node B receives the Resv message from leaf D, the label exchange relation in node B is set, and at the same time, the label value given to the transfer between node AB earlier because it is not the last Resv message, Furthermore, the Resv message containing the RRO information of the BD route is immediately transferred upstream.

The sending PE node A that receives the Resv message registers its own Resv state, and at the same time, sets the label transfer relationship in the FTN table and NHLFE table, and completes the partial P2MP LSP setting that reaches the leaves C and D. To do.

At the same time as this operation, node E receives the Resv message by downstream nodes F and G by the same mechanism as described in node B. After determining the Resv state on node E and building the label commutation relation, node E also immediately sends two corresponding Resv messages to node B on the upstream node. At this time, the first Resv message has a sequence number of 0 and the End bit is not specified, the second Resv message has a sequence number of 1, and the End bit is set, and this Resv message is the last Resv from the downstream. Indicates that it is a message. In this way, two more Resv messages arrive at node B from downstream, and node B sends the corresponding Resv message upstream, but when sending the last fourth Resv message, End with an update of the Seq bit. Bits are set and sent.

Through the above mechanism, the P2MP MPLS forwarding route is set at the end and end.

Figure 4 shows the message exchange sequence in the Path / Resv state maintenance state between nodes AB.

As described above, in this embodiment, since the P2MP LSP is set for the four leaf nodes C, D, F, and G, the node A holds itself for the node B. Based on the state information, four path messages are sent in the form shown in the figure. As shown in the figure, sequence numbers are assigned to retain partial information for each leaf, indicating that the final state is reached when the state information of (B, E, G), which is the last partial information, is exchanged. The End bit is assigned and the state is held. Furthermore, in response to this path message, a Resv message for confirming the partial status is sent. Similarly, the End bit is also added to the last partial state message (B, E, G).

[Second Embodiment]

In the present embodiment, the Grafting mechanism, which is an additional process of the partial P2MP LSP tree of the present invention, will be described with reference to FIGS. 5 and 6.

In the example of FIG. 5, an example of Grafting the leaf LSP: EH up to the node H under the node E is shown for the already set tree.

Leaf LSP: To Graft the EH, the sending PE node A prepares the designated route ERO = (A, B, E, H) to the additional receiving leaf H. The sending node then identifies how many partial states there are for the P2MP LSP that has already been configured. In this case, leaf nodes C, D, F, and G and four partial information exist, and the transmitting PE node already sets the P2MP LSP, but the sequence number of the P2MP session information is 0 to 3. It is assumed that you are using a value (3 is the last operation with the End bit specified). Since the sending PE node A holds this information, a new sequence number m = 4 is prepared not only for path maintenance of P2MP LSP but also for additional processing of a new subtree. After that, the sending node is already set in the P2MP session information and the partial P2MP LSP is additionally set in P2MP. Using P2MP_LSP_id to specify the LSP, further specify the new sequence number M = 4, and in this case, since only one LSP of EH is added, the P2MP session object with the End bit set and ERO as ERO. (B, E, H) is stored in the path message and immediately sent to the downstream node B.

When node B receives the path message, it determines that the path message is not a path message for state maintenance but a message of a tree change request by its sequence number m, so that the node B searches for the Path state information. At the same time as registering new information, the path message is analyzed for the ERO information held by the path message and immediately transferred to the corresponding downstream node, node E. At this time, the sequence number of the P2MP session of the two path messages (because the partial information is registered) between the nodes B and E is set to "2".

Further, the node E that has received the pass message determines that it is the partial LSP addition request information of the node EH, and newly transmits the pass message in the direction of the node EH. Note that the sequence number of this P2MP session object is "0" and the End bit is set. Thus, when the path message reaches leaf H, leaf H confirms the P2MP LSP by immediately sending a Resv message upstream if the partial LSP addition request is acceptable, as shown in Figure 6. To do. At this time, since it is the first partial information between the nodes EH as described above, the End bit is set with the sequence number: 0 and the notification is made upstream. Furthermore, since the third partial information is registered between the nodes BE, Seq = 2 and the End bit are set and the information is immediately notified upstream. Furthermore, since the fifth partial information is added between the nodes AB, Seq = 4, End bit is set and notified upstream.

[Third Embodiment]

In this embodiment, multicast MPLSP running will be described with reference to FIG.

In the example of Fig. 7, an example of pruning leaf LSP: EH from under node E of the already set P2MP LSP is shown.

The transmitting node A identifies ERO (A, B, E, H) which is subtree information for the leaf to be deleted from the {ERO} s information representing the tree-based route setting information of the P2MP LSP that has already been set. Node A identifies the {ERO} information to be deleted and the sequence number of the ERO (B, E, H) information between ABs that has already been set. In this example, as shown in the Grafting example above, ERO (B, E, H) is registered as seq = 4 between nodes AB. When this sequence number is specified, the sending PE node A is the P2MP for which the partial LSP is deleted as P2MP session information. Using the P2MP_LSP_id information that identifies the LSP, using the previous Seq = 4, and since this is one of the operations, set the End bit to use the P2MP session information of the PathTear message as the P2MP session information of the PathTear message, which is the target route to be deleted. Add the information of B, E, H), store it in the PathTear message, and send it to the downstream node B. Node B identifies the corresponding Path state from the received PathTear session information, deletes the ERO (B, E, H) information, and identifies the downstream node E including the tree to be deleted. At this time, between the nodes BE, BEH is managed by Seq = 2, so specify Seq = 2, and since this is one of the delete operations, set the End bit and then ERO (E, H). Also, send a PathTear message to E on the downstream node immediately. Similarly, the node E that receives the PathTear message deletes the EH information from the registered Path state, sets Seq = 0 and the End bit toward the downstream H, and sends the PathTear message. .. By executing this operation from upstream to downstream, the target deletion tree is deleted from the set tree.

[Fourth Embodiment]

FIG. 8 is a sequence diagram of a P2MP LSP path message when Loose is specified in the fourth embodiment of the present invention.

As shown in the figure, when an intermediate node that has received a plurality of path messages identifies the next hop set information from the TERO information included in the plurality of path messages, the address information specified as Loose in the next hop information. If is included, the process that enables P2MP tree-based LSP extension for the address group specified by Loose is performed.

In addition, the operation of each node in the first to fourth embodiments described above is constructed as a program, installed in the computer of each node, executed by a control means such as a CPU, or distributed via a network. Is also possible.

Furthermore, the constructed program can be stored in a hard disk connected to the computer of each node, a flexible disk, a portable storage medium such as a CD-ROM, installed in the computer, and executed.

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 a technique for setting a point-to-multipoint MPLS transfer route for MPLS-guaranteed MPLS transfer while efficiently TEing traffic for P2MP (point-to-multipoint) communication on a network database.

<figref num="1">It is a format of a P2MP session object in the first embodiment of the present invention.</figref><figref num="2">It is a sequence of the path message of P2MP LSP in the first embodiment of the present invention.</figref><figref num="3">It is a sequence of Resv messages of P2MP LSP in the first embodiment of the present invention.</figref><figref num="4">It is a message exchange sequence in the Path / Resv state maintenance state between the nodes AB in the first embodiment of the present invention.</figref><figref num="5">It is a sequence of the path message of the subtree P2MP LSP in the second embodiment of the present invention.</figref><figref num="6">It is a sequence of P2MP LSP grafting Resv messages in the second embodiment of the present invention.</figref><figref num="7">It is a sequence of the path message of the subtree P2MP LSP Pruning in the third embodiment of the present invention.</figref><figref num="8">It is a sequence diagram of the path message of P2MP LSP at the time of Loose designation in the 4th Embodiment of this invention.</figref>