CN112929275B - Central control-based PIM-SM multicast label routing method - Google Patents
Central control-based PIM-SM multicast label routing method Download PDFInfo
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- H04L45/50—Routing or path finding of packets in data switching networks using label swapping, e.g. multi-protocol label switch [MPLS]
Abstract
The invention discloses a method for routing a PIM-SM multicast label of a space-based network based on centralized control, which supports the interaction of a user network and the space-based network by adopting a standard PIM-SM multicast routing protocol and a standard multicast group protocol, and realizes the routing forwarding of a user IP multicast service in the space-based network. The system and the method are jointly completed by the integrated controller, the space-based network satellite node and the multicast function on the satellite terminal. The satellite terminal completes the conversion of a standard PIM-SM multicast routing protocol signaling, a standard multicast group protocol and a satellite side PIM-SM multicast label routing signaling, and the label encapsulation and the decapsulation of the IP multicast data; the space-based network satellite node completes inter-satellite forwarding of the IP data with the multicast label; the centralized controller and the satellite terminal complete the interaction of the routing signaling of the PIM-SM multicast label at the satellite side, calculate the multicast forwarding path and send the multicast forwarding path to the satellite terminal and the space-based network satellite node. The scheme can reduce the processing pressure and storage overhead of the satellite-borne equipment, and is suitable for space-based networks with limited satellite resources and link bandwidth.
Description
Technical Field
The invention relates to the technical field of heaven and earth integrated network communication, in particular to a PIM-SM multicast label routing method based on centralized control in a heaven-earth base network.
Background
The space-ground integrated network is an information network consisting of satellites, constellations and corresponding ground infrastructure with different orbits, types and characteristics, which are connected together through inter-satellite and satellite-ground links and can be divided into a space-based network, a space-based access network and a ground node network according to the difference of the functions of satellite nodes. The space-based network is mainly deployed in a layered mode by adopting multifunctional satellites or ground gateway stations distributed on different orbital planes such as GEO, IGSO or HEO, global seamless coverage is achieved, the space-based network is mainly used for extension and expansion of the ground network, and functions of flow sharing, communication guarantee in a hostile environment, global communication transmission and the like can be provided for the ground network.
In terrestrial networks, there are already a number of well-established multicast routing protocols, mainly including DVMRP, MOSPF, PIM-DM, PIM-SM, PIM-SSM, etc. These protocols are mainly used in wired networks with stable terrestrial topology. In the space-based network, due to the characteristics of link connection and disconnection, limited node capacity, terminal same-port communication and the like, the ground standard routing protocols are directly applied, and the effects on the aspects of network expansibility, mobility, safety and the like are not good.
At present, multicast routing algorithms in space-based low-orbit networks are researched more, and researchers at home and abroad research optimization strategies of low-orbit multicast routing from the aspects of reducing switching overhead, reducing system utilization rate, optimizing inter-satellite load balance, guaranteeing service quality and the like, and also provide a plurality of theoretical algorithms. The research on the multicast routing method of the space-based network is less, on one hand, the space-based network is relatively stable and simple in topology compared with the space-based low-orbit network, on the other hand, the single-satellite coverage area of the space-based network is larger, and the scenes of inter-satellite networking are fewer. However, with the construction of the world-wide integrated network and the proposal of the space-based network, the demand of the high-orbit inter-satellite networking is increasingly urgent, and the problem of the space-based network moving the ground standard routing protocol is gradually recognized.
Firstly, the multicast has the problem of same-port communication, in a space-based network, a satellite terminal is used as a multicast router to interact with a space-based network satellite node, the space-based network satellite node is mostly a high orbit satellite, a plurality of beams are arranged on the satellite, the coverage area of each beam is large, and when the satellite terminals in the beams perform multicast communication with each other, normal multicast routing protocol convergence cannot be performed, which is caused by different links of a ground network and a wireless network. At present, a known method is to set a switch when a satellite beam is forwarded at the same port, and when multicast communication in the beam is required, the switch is turned on, and multicast data is broadcast under the same beam so as to be received by a satellite terminal in the beam.
Secondly, the standard multicast routing protocol PIM-SM has poor expansibility in a space-based network, the standard multicast routing protocol PIM-SM depends on a unicast routing protocol, the state needs to be refreshed periodically, the multicast streaming state is maintained periodically, the capacity of a satellite-borne node is limited, and large-scale terminal networking cannot be supported.
Thirdly, the standard multicast routing protocol PIM-SM is designed aiming at a ground fixed network and cannot adapt to the characteristics of cross-satellite and cross-beam switching of a satellite terminal and the like, the standard multicast routing protocol PIM-SM does not support mobility, after a multicast router moves, an address is reconfigured, the unicast routing protocol is waited for convergence again, and the use of the standard multicast routing protocol PIM-SM in a space-based network is severely limited.
Finally, the standard multicast routing protocol PIM-SM adopts a distributed design, and cannot perform effective control for a multicast source and a multicast receiver entering a space-based network, the routing protocol is easily attacked, and multicast traffic is easily induced, which leads to poor security of the space-based network.
Disclosure of Invention
The invention aims to solve the technical problem of avoiding the problems in the background art and discloses a method for routing a PIM-SM multicast label based on a centrally controlled sky-based network, which supports a user network to interact with the sky-based network by adopting a standard PIM-SM multicast routing protocol and a standard multicast group protocol, and realizes the routing forwarding of user IP multicast service in the sky-based network.
The technical scheme adopted by the invention is as follows:
a centralized control-based PIM-SM multicast label routing method comprises the following steps:
(1) the centralized controller periodically sends controller broadcast messages, and all satellite terminals receive the controller broadcast messages after accessing the network;
(2) all satellite terminals interact PIM-SM protocol messages with routers of a user network on the ground side or interact standard multicast group protocol messages with a host computer; meanwhile, sending a PIM-SM multicast satellite terminal registration message to the centralized controller at the satellite side according to the controller address information in the received controller broadcast message, and after receiving the terminal registration message, distinguishing the multicast protocol type registered by the satellite terminal as PIM-SM to form a PIM-SM multicast domain and sending a registration response to the satellite terminal by the centralized controller;
(3) after a downstream satellite terminal receives a PIM-SM multicast join message or a join multicast group message of a ground side user network, the downstream satellite terminal sends the PIM-SM multicast G join message to an upstream satellite terminal in which an RP router is positioned in a unicast mode, and sends the PIM-SM multicast G label join message to a centralized controller;
(4) the centralized controller establishes a G multicast forwarding tree taking a satellite to which an upstream RP router belongs as a root according to the received PIM-SM multicast G label adding message, distributes multicast labels, generates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, issues the G multicast label forwarding table to each space-based network satellite node through a southbound interface protocol, and configures the G multicast label mapping table to an upstream satellite terminal where the RP router is located; after receiving PIM-SM multicast G adding information sent by a downstream satellite terminal, an upstream satellite terminal where the RP router is located processes according to G adding flow specified by a standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process;
(5) when the upstream user multicast IP data reaches an upstream satellite terminal, firstly searching the multicast IP route, and after the search is successful, searching a G multicast label mapping table according to a multicast destination address G, packaging a multicast label and a satellite link layer frame header according to the search result, and sending the packaged satellite multicast data to a space-based network satellite node;
(6) the space-based network satellite node extracts a multicast label encapsulated in the satellite multicast data, matches the multicast label in the G multicast label forwarding table, determines an exit list after matching is successful, and forwards the satellite multicast data stream through the exit list; if the exit list contains multicast entries and the multicast entries are intersatellite link ports, forcibly removing the multicast entries from the exit list;
(7) after receiving the satellite multicast data, the satellite terminal in the downstream of the multicast carries out decapsulation on the multicast label, then carries out multicast IP routing and forwards the multicast label to the downstream user network through the multicast IP routing.
Wherein, the following processes are also included after the step (7):
(8) when the last hop PIM-SM router initiates SPT switching, after a downstream satellite terminal generates or receives a PIM-SM SG joining message sent by a user network, the downstream satellite terminal sends a PIM-SM multicast SG joining message to an upstream satellite terminal in which a multicast source is positioned in a unicast mode, and sends a PIM-SM multicast SG label joining message to the centralized controller;
(9) after adding information according to the received PIM-SM multicast SG label, the centralized controller searches a corresponding G multicast forwarding tree, if an SG multicast source and an RP router are positioned at the same upstream satellite terminal, the G multicast forwarding tree is updated into the SG multicast forwarding tree, and a multicast label mapping table updating message is sent to the upstream satellite terminal where the RP router is positioned; if the SG multicast source and the RP router are positioned at different upstream satellite terminals, an SG multicast forwarding tree is established, a multicast label is distributed for the SG, an SG multicast forwarding path, an SG multicast label forwarding table and an SG multicast label mapping table are generated, the SG multicast label forwarding table is issued to each space-based network satellite node through a southbound interface protocol, and SG multicast label mapping table configuration information is sent to the upstream satellite terminal where the multicast source is positioned;
(10) after receiving a unicast PIM-SM multicast SG label joining message sent by a downstream satellite terminal, an upstream satellite terminal where a multicast source is located processes according to an SG joining flow specified by a standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process.
After the step (4), if the downstream satellite terminal receives a PIM-SM G pruning message sent by the user network, the following processing is performed:
after receiving the PIM-SM G pruning message, the downstream satellite terminal unicast-sends a PIM-SM multicast G pruning message to the upstream satellite terminal where the RP router is located, and sends a PIM-SM multicast G label pruning message to the centralized controller;
the centralized controller searches a corresponding G multicast forwarding tree according to the received PIM-SM multicast G label pruning message, deletes the downstream satellite terminal from the G multicast forwarding tree, recalculates and updates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, sends a G multicast label forwarding table updating message to a space-based network satellite node on a new multicast path through a southbound interface protocol if the downstream satellite terminal changes, sends a multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, and sends a G multicast label forwarding table updating or deleting message to an upstream satellite terminal where the RP router is located through a G multicast label mapping table configuration signaling of the satellite terminal.
After receiving a unicast PIM-SM multicast G pruning message sent by a downstream satellite terminal, an upstream satellite terminal processes the message according to a G pruning flow specified by a standard PIM-SM protocol, and does not carry out neighbor validity check in the processing process;
if the downstream satellite terminal receives the leaving group message sent by the user network and the SPT switching does not occur, the following processing is carried out:
a downstream satellite terminal unicast-sends a PIM-SM multicast G pruning message to an upstream satellite terminal where the RP router is located, and sends a PIM-SM multicast G label pruning message to the centralized controller;
the centralized controller searches a corresponding G multicast forwarding tree according to the received PIM-SM multicast G label pruning message, deletes the downstream satellite terminal from the G multicast forwarding tree, recalculates and updates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, if the downstream satellite terminal changes, sends a G multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol, sends a G multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, and sends a G multicast label mapping table updating or deleting message to an upstream satellite terminal where the RP router is located through a multicast mapping table configuration signaling of the satellite terminal;
and after receiving the PIM-SM multicast G pruning message sent by the downstream satellite terminal, the upstream satellite terminal carries out processing according to the G pruning flow specified by the standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process.
Wherein, the following processes are also included after the step (10):
if the downstream satellite terminal has SPT switching and receives a group leaving message sent by a user network, or the downstream satellite terminal receives a PIM-SM SG pruning message sent by the user network, the upstream satellite terminal where the multicast source is located unicast-sends the PIM-SM multicast SG pruning message, and sends the PIM-SM multicast SG label pruning message to the centralized controller;
the centralized controller searches a corresponding PIM-SM SG multicast forwarding tree according to the received PIM-SM multicast SG label pruning message, deletes the downstream satellite terminal from the SG multicast forwarding tree, recalculates and updates an SG multicast forwarding path, an SG multicast label forwarding table and an SG multicast label mapping table, if the downstream satellite terminal is changed, sends a multicast forwarding table updating message to a space-based network satellite node on the new multicast path through a southward interface protocol, sends a multicast forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, and sends a multicast mapping table updating or deleting message to an upstream satellite terminal where a multicast source is located;
and after receiving the unicast PIM-SM multicast SG pruning message sent by the downstream satellite terminal, the upstream satellite terminal where the multicast source is located processes according to an SG pruning flow specified by a standard PIM-SM protocol, and does not carry out neighbor validity check in the processing process.
Wherein, step (4) also includes after:
(11) when the space-based network inter-satellite-ground topology changes, the centralized controller recalculates the SG or G multicast forwarding tree in use at present according to the new topology, updates an SG or G multicast forwarding path, updates an SG or G multicast label forwarding table, and sends a multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol and a multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more if the SG or G multicast forwarding table is changed;
(12) when the PIM-SM multicast satellite terminal moves across beams and satellites, the satellite terminal resends registration information to the centralized controller, the number and the port number of the satellite where the satellite terminal is located at present are updated, the centralized controller recalculates a multicast forwarding tree related to the moving satellite terminal, updates an SG or G multicast forwarding path, updates an SG or G multicast label forwarding table, and sends a multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol if the multicast forwarding table is changed, and sends a multicast label deleting message to a space-based network satellite node on the old path which is not used any more.
A keep-alive mechanism exists between the satellite terminal and the centralized controller, and the satellite terminal fails to receive the broadcast information of the centralized controller within the overtime time and then loses address information of the centralized controller; the centralized controller maintains all successfully registered satellite terminals operating PIM-SM multicast protocol to form a PIM-SM multicast domain, after the satellite terminals quit the network, the centralized controller loses the registration information and the multicast forwarding state information associated with the satellite terminals, recalculates the multicast forwarding tree, and deletes the multicast forwarding information associated with the satellite terminals on the path.
The south interface protocol adopted between the centralized controller and the space-based network satellite node is a standard protocol or a self-defined private protocol; the PIM-SM multicast label routing signaling between the centralized controller and the satellite terminal is a periodic interaction without confirmation or a one-time interaction mechanism with confirmation.
The PIM-SM multicast satellite terminal registration message sent by the satellite terminal to the centralized controller comprises a destination station number of the satellite terminal, a satellite number and a port number where the satellite terminal is located, keep-alive keeping time and an IP address.
The centralized controller searches the successfully registered PIM-SM multicast satellite terminal according to the station number of the satellite terminal where the multicast source or RP router is located, and acquires the tree root of the multicast forwarding tree.
Wherein the PIM-SM protocol is IPv4PIM-SM protocol or IPv6 PIM-SM.
Compared with the background technology, the invention has the following advantages:
by adopting the PIM-SM multicast routing scheme, a plurality of problems of applying a ground standard multicast routing protocol PIM-SM in a space-based network can be avoided.
The invention adopts a two-layer multicast label routing scheme based on centralized control, does not distinguish the same multicast port from the non-same multicast port, dynamically calculates the multicast path and the multicast label forwarding table according to the position of the multicast source and the joining condition of the multicast receivers, treats the joining of the multicast receivers of the multicast source at the same port as the joining of the multicast receivers at different ports in the same way, and naturally avoids the problem of the communication of the multicast at the same port.
Secondly, the two-layer multicast label routing scheme adopts a lightweight control framework, the cost of PIM-SM multicast label routing signaling is far lower than that of a ground standard multicast routing protocol PIM-SM, the satellite does not need to maintain a multicast forwarding state in proportion to multicast composition, the satellite processing burden is greatly reduced, and the supported multicast network scale is much larger than that of the standard multicast routing protocol, so that the expansibility of the networking scale is superior to that of the ground standard multicast routing protocol PIM-SM.
Then, the multicast label routing scheme based on two layers can support the rapid movement of the node, and benefits from the label-based routing exchange architecture, the IP identity information and the position label information of the space-based network are separated, the movement of the satellite terminal is equivalent to the movement in the two-layer label position network, and the IP address does not need to be redistributed, therefore, the invention can support the rapid movement of the satellite terminal crossing the satellite and crossing the wave beam, and can realize the seamless switching of the service by combining with the network control network management mechanism of the satellite terminal.
Finally, the two-layer multicast label routing scheme is based on a centralized control strategy, and when the satellite terminal sends or receives multicast data, the two-layer multicast label routing scheme needs to register with the centralized controller, so that the validity authentication of real-time multicast participants and multicast signaling messages is facilitated, and the multicast security control of a space-based network is facilitated to be improved on the framework.
The two-layer multicast label routing scheme based on centralized control has the greatest advantage of being compatible with a standard multicast routing protocol PIM-SM and a standard multicast group protocol, and supporting a multicast router or a host of a user network to interact with a space-based network by adopting the standard multicast routing protocol PIM-SM and the standard multicast group protocol, thereby realizing the space-ground interconnection and intercommunication of multicast IP services.
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Fig. 1 is an exemplary diagram of an application scenario of the present invention.
Detailed Description
While the preferred embodiment of the present invention will be described with reference to fig. 1, it is to be understood that the preferred embodiment described herein is merely for purposes of illustration and explanation and is not intended to be a limitation of the present invention.
The invention is completed by the multicast function of the entities such as the centralized controller, the space-based network satellite node, the satellite terminal and the like. The satellite terminal is used as a connecting device of a user network and a space-based network to complete conversion of a standard PIM-SM multicast routing protocol signaling, a standard multicast group protocol and a satellite side PIM-SM multicast label routing signaling, and label encapsulation and decapsulation of IP multicast data; the space-based network satellite node completes inter-satellite forwarding of the IP data with the multicast label; the centralized controller and the satellite terminal complete the interaction of the routing signaling of the PIM-SM multicast label at the satellite side, calculate the multicast forwarding path and send the multicast forwarding path to the satellite terminal and the space-based network satellite node. Compared with a standard PIM-SM protocol, the scheme can greatly reduce the processing pressure and storage cost of the satellite-borne equipment, and is particularly suitable for space-based networks with limited satellite resources and limited link bandwidth by externally compatible a standard PIM-SM multicast routing protocol and a standard multicast group protocol through a satellite terminal.
Fig. 1 shows a typical embodiment of using the PIM-SM multicast label routing method to perform the intercommunication of the heaven and earth IP multicast, in which the communication entities include 3 heaven-base network satellite nodes, 1 centralized controller, 3 satellite terminals, 1 multicast source computer, 2 multicast receiving computers, and 2 commercial routers. The 3 space-based network satellite nodes are connected into a ring topology through inter-satellite links, the centralized controller is positioned at a gateway station and is in control connection with each space-based network satellite node, the user network 1 comprises 1 multicast source computer and 1 commercial router, the 1 multicast receiving computer in the user network 2 is directly hung behind the satellite terminal, and the 1 multicast receiving computer in the user network 3 is hung behind the satellite terminal through the 1 commercial router.
Wherein, a multicast source computer in a user network 1 sends multicast IP data, multicast receiving computers in a user network 2 and a user network 3 start a multicast receiving program, commercial routers in the user network 1 and the user network 3 start a standard multicast routing protocol PIM-SM, a scene that the multicast source sends the multicast IP data and the multicast data is routed and forwarded through a space-based network is shown in the figure, an upstream satellite terminal in the user network 1 adopts a standard PIM-SM protocol to interact with the commercial routers, the multicast IP data is packaged with a multicast label configured by a centralized controller and is forwarded to the space-based network satellite node 1, the space-based network satellite node 1 forwards the multicast data to the space-based network satellite node 2, the space-based network satellite node 3, and after downstream satellite terminals under respective ports of the space-based network satellite node 2 and the space-based network satellite node 3 receive the multicast label data, and forwarding the multicast data to a local user network, wherein the local user network finally forwards the multicast data to a multicast receiving computer by adopting a standard multicast routing method.
The invention discloses a method for routing a PIM-SM multicast label of a space-based network based on centralized control, which supports a user network to interact with the space-based network by adopting a standard PIM-SM multicast routing protocol and a standard multicast group protocol, and realizes the routing forwarding of a user IP multicast service in the space-based network. The method specifically comprises the following steps:
(1) the centralized controller periodically sends controller broadcast messages, and all satellite terminals receive the controller broadcast messages after accessing the network;
(2) all satellite terminals interact PIM-SM protocol messages with routers of a user network on the ground side or interact standard multicast group protocol messages with a host computer; meanwhile, sending a PIM-SM multicast satellite terminal registration message to the centralized controller at the satellite side according to the controller address information in the received controller broadcast message, and after receiving the terminal registration message, distinguishing the multicast protocol type registered by the satellite terminal as PIM-SM to form a PIM-SM multicast domain and sending a registration response to the satellite terminal by the centralized controller;
(3) after a downstream satellite terminal receives a PIM-SM multicast join message or a join multicast group message of a ground side user network, the downstream satellite terminal sends the PIM-SM multicast G join message to an upstream satellite terminal in which an RP router is positioned in a unicast mode, and sends the PIM-SM multicast G label join message to a centralized controller;
(4) the centralized controller establishes a G multicast forwarding tree taking a satellite to which an upstream RP router belongs as a root according to the received PIM-SM multicast G label adding message, distributes multicast labels, generates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, issues the G multicast label forwarding table to each space-based network satellite node through a southbound interface protocol, and configures the G multicast label mapping table to an upstream satellite terminal where the RP router is located; after receiving PIM-SM multicast G adding information sent by a downstream satellite terminal, an upstream satellite terminal where the RP router is located processes according to G adding flow specified by a standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process;
(5) when the upstream user multicast IP data reaches an upstream satellite terminal, firstly searching the multicast IP route, and after the search is successful, searching a G multicast label mapping table according to a multicast destination address G, packaging a multicast label and a satellite link layer frame header according to the search result, and sending the packaged satellite multicast data to a space-based network satellite node;
(6) the space-based network satellite node extracts a multicast label encapsulated in the satellite multicast data, matches the multicast label in the G multicast label forwarding table, determines an exit list after matching is successful, and forwards the satellite multicast data stream through the exit list; if the exit list contains multicast entries and the multicast entries are intersatellite link ports, forcibly removing the multicast entries from the exit list;
(7) after receiving the satellite multicast data, the satellite terminal in the downstream of the multicast carries out decapsulation on the multicast label, then carries out multicast IP routing and forwards the multicast label to the downstream user network through the multicast IP routing.
Wherein, the following processes are also included after the step (7):
(8) when the last hop PIM-SM router initiates SPT switching, after a downstream satellite terminal generates or receives a PIM-SM SG joining message sent by a user network, the downstream satellite terminal sends a PIM-SM multicast SG joining message to an upstream satellite terminal in which a multicast source is positioned in a unicast mode, and sends a PIM-SM multicast SG label joining message to the centralized controller;
(9) after adding information according to the received PIM-SM multicast SG label, the centralized controller searches a corresponding G multicast forwarding tree, if an SG multicast source and an RP router are positioned at the same upstream satellite terminal, the G multicast forwarding tree is updated into the SG multicast forwarding tree, and a multicast label mapping table updating message is sent to the upstream satellite terminal where the RP router is positioned; if the SG multicast source and the RP router are positioned at different upstream satellite terminals, an SG multicast forwarding tree is established, a multicast label is distributed for the SG, an SG multicast forwarding path, an SG multicast label forwarding table and an SG multicast label mapping table are generated, the SG multicast label forwarding table is issued to each space-based network satellite node through a southbound interface protocol, and SG multicast label mapping table configuration information is sent to the upstream satellite terminal where the multicast source is positioned;
(10) after receiving a unicast PIM-SM multicast SG label joining message sent by a downstream satellite terminal, an upstream satellite terminal where a multicast source is located processes according to an SG joining flow specified by a standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process.
After the step (4), if the downstream satellite terminal receives a PIM-SM G pruning message sent by the user network, the following processing is performed:
after receiving the PIM-SM G pruning message, the downstream satellite terminal unicast-sends a PIM-SM multicast G pruning message to the upstream satellite terminal where the RP router is located, and sends a PIM-SM multicast G label pruning message to the centralized controller;
the centralized controller searches a corresponding G multicast forwarding tree according to the received PIM-SM multicast G label pruning message, deletes the downstream satellite terminal from the G multicast forwarding tree, recalculates and updates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, sends a G multicast label forwarding table updating message to a space-based network satellite node on a new multicast path through a southbound interface protocol if the downstream satellite terminal changes, sends a multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, and sends a G multicast label forwarding table updating or deleting message to an upstream satellite terminal where the RP router is located through a G multicast label mapping table configuration signaling of the satellite terminal.
After receiving a unicast PIM-SM multicast G pruning message sent by a downstream satellite terminal, an upstream satellite terminal processes the message according to a G pruning flow specified by a standard PIM-SM protocol, and does not carry out neighbor validity check in the processing process;
if the downstream satellite terminal receives the leaving group message sent by the user network and the SPT switching does not occur, the following processing is carried out:
a downstream satellite terminal unicast-sends a PIM-SM multicast G pruning message to an upstream satellite terminal where the RP router is located, and sends a PIM-SM multicast G label pruning message to the centralized controller;
the centralized controller searches a corresponding G multicast forwarding tree according to the received PIM-SM multicast G label pruning message, deletes the downstream satellite terminal from the G multicast forwarding tree, recalculates and updates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, if the downstream satellite terminal changes, sends a G multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol, sends a G multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, and sends a G multicast label mapping table updating or deleting message to an upstream satellite terminal where the RP router is located through a multicast mapping table configuration signaling of the satellite terminal;
and after receiving the PIM-SM multicast G pruning message sent by the downstream satellite terminal, the upstream satellite terminal carries out processing according to the G pruning flow specified by the standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process.
Wherein, the following processes are also included after the step (10):
if the downstream satellite terminal has SPT switching and receives a group leaving message sent by a user network, or the downstream satellite terminal receives a PIM-SM SG pruning message sent by the user network, the upstream satellite terminal where the multicast source is located unicast-sends the PIM-SM multicast SG pruning message, and sends the PIM-SM multicast SG label pruning message to the centralized controller;
the centralized controller searches a corresponding PIM-SM SG multicast forwarding tree according to the received PIM-SM multicast SG label pruning message, deletes the downstream satellite terminal from the SG multicast forwarding tree, recalculates and updates an SG multicast forwarding path, an SG multicast label forwarding table and an SG multicast label mapping table, if the downstream satellite terminal is changed, sends a multicast forwarding table updating message to a space-based network satellite node on the new multicast path through a southward interface protocol, sends a multicast forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, and sends a multicast mapping table updating or deleting message to an upstream satellite terminal where a multicast source is located;
and after receiving the unicast PIM-SM multicast SG pruning message sent by the downstream satellite terminal, the upstream satellite terminal where the multicast source is located processes according to an SG pruning flow specified by a standard PIM-SM protocol, and does not carry out neighbor validity check in the processing process.
Wherein, step (4) also includes after:
(11) when the space-based network inter-satellite-ground topology changes, the centralized controller recalculates the SG or G multicast forwarding tree in use at present according to the new topology, updates an SG or G multicast forwarding path, updates an SG or G multicast label forwarding table, and sends a multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol and a multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more if the SG or G multicast forwarding table is changed;
(12) when the PIM-SM multicast satellite terminal moves across beams and satellites, the satellite terminal resends registration information to the centralized controller, the number and the port number of the satellite where the satellite terminal is located are updated, the centralized controller recalculates a multicast forwarding tree related to the moving satellite terminal, updates an SG or G multicast forwarding path, updates an SG or G multicast label forwarding table, and if the multicast forwarding table changes, sends a multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol, sends a multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, recalculates the multicast forwarding tree, and deletes multicast forwarding information related to the satellite terminal on the path.
A keep-alive mechanism exists between the satellite terminal and the centralized controller, and the satellite terminal fails to receive the broadcast information of the centralized controller within the overtime time and then loses address information of the centralized controller; the centralized controller maintains all successfully registered satellite terminals operating the PIM-SM multicast protocol to form a PIM-SM multicast domain, and after the satellite terminals quit the network, the centralized controller fails to validate the registration information and the multicast forwarding state information associated with the satellite terminals.
The south interface protocol adopted between the centralized controller and the space-based network satellite node is a standard protocol or a self-defined private protocol; the PIM-SM multicast label routing signaling between the centralized controller and the satellite terminal is a periodic interaction without confirmation or a one-time interaction mechanism with confirmation.
The PIM-SM multicast satellite terminal registration message sent by the satellite terminal to the centralized controller comprises a destination station number of the satellite terminal, a satellite number and a port number where the satellite terminal is located, keep-alive keeping time and an IP address.
The centralized controller searches the successfully registered PIM-SM multicast satellite terminal according to the station number of the satellite terminal where the multicast source or RP router is located, and acquires the tree root of the multicast forwarding tree.
Wherein the PIM-SM protocol is IPv4PIM-SM protocol or IPv6 PIM-SM.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A centralized control-based PIM-SM multicast label routing method is realized by a satellite terminal, a centralized controller and multicast routing functions on a space-based network satellite node, and is characterized by comprising the following steps:
(1) the centralized controller periodically sends controller broadcast messages, and all satellite terminals receive the controller broadcast messages after accessing the network;
(2) all satellite terminals interact PIM-SM protocol messages with routers of a user network on the ground side or interact standard multicast group protocol messages with a host computer; meanwhile, sending a PIM-SM multicast satellite terminal registration message to the centralized controller at the satellite side according to the controller address information in the received controller broadcast message, and after receiving the terminal registration message, distinguishing the multicast protocol type registered by the satellite terminal as PIM-SM to form a PIM-SM multicast domain and sending a registration response to the satellite terminal by the centralized controller;
(3) after a downstream satellite terminal receives a PIM-SM multicast join message or a join multicast group message of a ground side user network, the downstream satellite terminal sends the PIM-SM multicast G join message to an upstream satellite terminal in which an RP router is positioned in a unicast mode, and sends the PIM-SM multicast G label join message to a centralized controller;
(4) the centralized controller establishes a G multicast forwarding tree taking a satellite to which an upstream RP router belongs as a root according to the received PIM-SM multicast G label adding message, distributes multicast labels, generates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, issues the G multicast label forwarding table to each space-based network satellite node through a southbound interface protocol, and configures the G multicast label mapping table to an upstream satellite terminal where the RP router is located; after receiving PIM-SM multicast G adding information sent by a downstream satellite terminal, an upstream satellite terminal where the RP router is located processes according to G adding flow specified by a standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process;
(5) when the upstream user multicast IP data reaches an upstream satellite terminal, firstly searching the multicast IP route, and after the search is successful, searching a G multicast label mapping table according to a multicast destination address G, packaging a multicast label and a satellite link layer frame header according to the search result, and sending the packaged satellite multicast data to a space-based network satellite node;
(6) the space-based network satellite node extracts a multicast label encapsulated in the satellite multicast data, matches the multicast label in the G multicast label forwarding table, determines an exit list after matching is successful, and forwards the satellite multicast data stream through the exit list; if the exit list contains multicast entries and the multicast entries are intersatellite link ports, forcibly removing the multicast entries from the exit list;
(7) after receiving the satellite multicast data, the downstream satellite terminal of the multicast carries out decapsulation on the multicast label, then carries out multicast IP routing and forwards the multicast label to a downstream user network through the multicast IP routing;
after the step (4), the method further comprises the following steps:
(11) when the space-based network inter-satellite-ground topology changes, the centralized controller recalculates the SG or G multicast forwarding tree in use at present according to the new topology, updates an SG or G multicast forwarding path, updates an SG or G multicast label forwarding table, and sends a multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol and a multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more if the SG or G multicast forwarding table is changed;
(12) when the PIM-SM multicast satellite terminal moves across beams and satellites, the satellite terminal resends registration information to the centralized controller, the number and the port number of the satellite where the satellite terminal is located at present are updated, the centralized controller recalculates a multicast forwarding tree related to the moving satellite terminal, updates an SG or G multicast forwarding path, updates an SG or G multicast label forwarding table, and sends a multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol if the multicast forwarding table is changed, and sends a multicast label deleting message to a space-based network satellite node on the old path which is not used any more.
2. The PIM-SM multicast label routing method based on centralized control as claimed in claim 1, further comprising the following steps after step (7):
(8) when the last hop PIM-SM router initiates SPT switching, after a downstream satellite terminal generates or receives a PIM-SM SG joining message sent by a user network, the downstream satellite terminal sends a PIM-SM multicast SG joining message to an upstream satellite terminal in which a multicast source is positioned in a unicast mode, and sends a PIM-SM multicast SG label joining message to the centralized controller;
(9) after adding information according to the received PIM-SM multicast SG label, the centralized controller searches a corresponding G multicast forwarding tree, if an SG multicast source and an RP router are positioned at the same upstream satellite terminal, the G multicast forwarding tree is updated into the SG multicast forwarding tree, and a multicast label mapping table updating message is sent to the upstream satellite terminal where the RP router is positioned; if the SG multicast source and the RP router are positioned at different upstream satellite terminals, an SG multicast forwarding tree is established, a multicast label is distributed for the SG, an SG multicast forwarding path, an SG multicast label forwarding table and an SG multicast label mapping table are generated, the SG multicast label forwarding table is issued to each space-based network satellite node through a southbound interface protocol, and SG multicast label mapping table configuration information is sent to the upstream satellite terminal where the multicast source is positioned;
(10) after receiving a unicast PIM-SM multicast SG label joining message sent by a downstream satellite terminal, an upstream satellite terminal where a multicast source is located processes according to an SG joining flow specified by a standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process.
3. The method according to claim 2, wherein after the step (4), if the downstream satellite terminal receives a PIM-SM multicast G pruning message sent by the user network, the following processing is performed:
after receiving the PIM-SM G pruning message, the downstream satellite terminal unicast-sends a PIM-SM multicast G pruning message to the upstream satellite terminal where the RP router is located, and sends a PIM-SM multicast G label pruning message to the centralized controller;
the centralized controller searches a corresponding G multicast forwarding tree according to the received PIM-SM multicast G label pruning message, deletes the downstream satellite terminal from the G multicast forwarding tree, recalculates and updates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, if the downstream satellite terminal changes, sends a G multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol, sends a multicast label deleting message to a space-based network satellite node on an old path which is not used any more, and sends a G multicast label forwarding table updating or deleting message to an upstream satellite terminal where the RP router is located through a G multicast label mapping table configuration signaling of the satellite terminal;
after receiving a unicast PIM-SM multicast G pruning message sent by a downstream satellite terminal, an upstream satellite terminal processes the message according to a G pruning flow specified by a standard PIM-SM protocol, and does not carry out neighbor validity check in the processing process;
if the downstream satellite terminal receives the leaving group message sent by the user network and the SPT switching does not occur, the following processing is carried out:
a downstream satellite terminal unicast-sends a PIM-SM multicast G pruning message to an upstream satellite terminal where the RP router is located, and sends a PIM-SM multicast G label pruning message to the centralized controller;
the centralized controller searches a corresponding G multicast forwarding tree according to the received PIM-SM multicast G label pruning message, deletes the downstream satellite terminal from the G multicast forwarding tree, recalculates and updates a G multicast forwarding path, a G multicast label forwarding table and a G multicast label mapping table, if the downstream satellite terminal changes, sends a G multicast label forwarding table updating message to a space-based network satellite node on the new multicast path through a southbound interface protocol, sends a G multicast label forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, and sends a G multicast label mapping table updating or deleting message to an upstream satellite terminal where the RP router is located through a multicast mapping table configuration signaling of the satellite terminal;
and after receiving the PIM-SM multicast G pruning message sent by the downstream satellite terminal, the upstream satellite terminal carries out processing according to the G pruning flow specified by the standard PIM-SM protocol, and neighbor validity check is not carried out in the processing process.
4. The PIM-SM multicast label routing method based on centralized control as claimed in claim 2, further comprising the following steps after step (10):
if the downstream satellite terminal has SPT switching and receives a group leaving message sent by a user network, or the downstream satellite terminal receives a PIM-SM SG pruning message sent by the user network, the upstream satellite terminal where the multicast source is located unicast-sends the PIM-SM multicast SG pruning message, and sends the PIM-SM multicast SG label pruning message to the centralized controller;
the centralized controller searches a corresponding PIM-SM SG multicast forwarding tree according to the received PIM-SM multicast SG label pruning message, deletes the downstream satellite terminal from the SG multicast forwarding tree, recalculates and updates an SG multicast forwarding path, an SG multicast label forwarding table and an SG multicast label mapping table, if the downstream satellite terminal is changed, sends a multicast forwarding table updating message to a space-based network satellite node on the new multicast path through a southward interface protocol, sends a multicast forwarding table deleting message to a space-based network satellite node on an old path which is not used any more, and sends a multicast mapping table updating or deleting message to an upstream satellite terminal where a multicast source is located;
and after receiving the unicast PIM-SM multicast SG pruning message sent by the downstream satellite terminal, the upstream satellite terminal where the multicast source is located processes according to an SG pruning flow specified by a standard PIM-SM protocol, and does not carry out neighbor validity check in the processing process.
5. The PIM-SM multicast label routing method based on centralized control according to claim 1, wherein a keep-alive mechanism exists between the satellite terminal and the centralized controller, and the satellite terminal fails to receive the broadcast information of the centralized controller within a timeout period, and then fails address information of the centralized controller; the centralized controller maintains all successfully registered satellite terminals operating PIM-SM multicast protocol to form a PIM-SM multicast domain, after the satellite terminals quit the network, the centralized controller loses the registration information and the multicast forwarding state information associated with the satellite terminals, recalculates the multicast forwarding tree, and deletes the multicast forwarding information associated with the satellite terminals on the path.
6. The PIM-SM multicast label routing method based on centralized control as claimed in claim 1, wherein the southbound interface protocol employed between the centralized controller and the satellite nodes of the space-based network is a standard protocol or a custom proprietary protocol; the PIM-SM multicast label routing signaling between the centralized controller and the satellite terminal is a periodic interaction without confirmation or a one-time interaction mechanism with confirmation.
7. The PIM-SM multicast label routing method based on centralized control as claimed in claim 1, wherein the PIM-SM multicast satellite terminal registration message sent by the satellite terminal to the centralized controller contains the destination station number of the satellite terminal, the satellite number and port number where the satellite terminal is located, keep-alive hold time and IP address.
8. The method according to claim 1, wherein the satellite terminal at least carries the station number of the satellite terminal where the multicast source or RP router is located in the PIM-SM multicast G tag join message or the PIM-SM multicast SG tag join message sent to the centralized controller, and the centralized controller searches for the successfully registered PIM-SM multicast satellite terminal according to the station number of the satellite terminal where the multicast source or RP router is located, and obtains the tree root of the multicast forwarding tree.
9. The PIM-SM multicast label routing method based on centralized control as claimed in any one of claims 1-8, wherein the PIM-SM protocol is IPv4PIM-SM protocol or IPv6 PIM-SM.
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