CN106411736B - Node resource discovery strategy optimization method for software-defined satellite network - Google Patents

Node resource discovery strategy optimization method for software-defined satellite network Download PDF

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CN106411736B
CN106411736B CN201611013297.0A CN201611013297A CN106411736B CN 106411736 B CN106411736 B CN 106411736B CN 201611013297 A CN201611013297 A CN 201611013297A CN 106411736 B CN106411736 B CN 106411736B
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information
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switch
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CN106411736A (en
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卢宁宁
付文亮
张海鹏
杨悦
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CETC 54 Research Institute
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/02—Topology update or discovery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/12—Shortest path evaluation
    • H04L45/121—Shortest path evaluation by minimising delays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/12—Shortest path evaluation
    • H04L45/123—Evaluation of link metrics
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks

Abstract

The invention discloses a node resource discovery strategy optimization method for a software-defined satellite network, and relates to the field of software-defined satellite networks. The invention reduces Packet-out information, enlarges link discovery period, optimizes link Packet loss and link failure coping strategies by optimizing LLDP protocol in the link discovery process, and improves the real-time and dynamic property of topology information update in the software defined satellite network; in the resource collection process, the idea of source routing is utilized, the matching domain of OpenFlow is added, the convergence time of setting a flow table in the network is reduced, the number of packet-out information of resource collection is reduced, and the load of network resources and a controller is reduced.

Description

Node resource discovery strategy optimization method for software-defined satellite network
Technical Field
The invention relates to the field of Software Defined Satellite Networks (SDSN), in particular to a method for improving timeliness of node resource discovery in a Software Defined Satellite Network.
Background
Resource discovery includes two processes, link discovery and resource collection. Link discovery is an important part of network topology, is the basis of resource discovery, and provides the most basic network resource information (link on-off information, node information, etc.). At the link discovery level, the network topology in a software defined satellite network can be described from three levels: the system comprises a link layer topology, a network layer topology and an overlay layer topology, and analyzes a network topology discovery mechanism from four levels of an IP interface, a router, an autonomous system and a Point of Presence (POP).
The standard of Link Discovery is the Link Layer Discovery Protocol (LLDP). Through the LLDP standard protocol, the AP sends the local LLDP information to the neighbor periodically through a standard LLDP TLV (type length value) multicast packet. If the neighbor AP also uses the LLDP function, the other side establishes a neighbor relation, if the AP uplink port is connected with a switch (equipment with the LLDP function) and the switch enables the LLDP function, the switch is also a neighbor of the AP, the AP sends LLDP information to the switch and receives the LLDP multicast message sent by the switch. And the network manager acquires the LLDP information of the AP through the SNMP protocol and maintains the topology information.
Link discovery does not provide information on computing power, storage capacity, etc. in the satellite network nodes and requires other methods to obtain it. In previous studies, the following thought methods were mainly used to solve the problem of resource collection:
in a traditional hop-by-hop routing software defined network, a controller issues resource collection packet-out packets to all discovered nodes, and periodically collects resource data to activated nodes, which causes large consumption of network resources and computing resources of the controller, easily causes problems of packet loss, link failure and the like in hesitation of the particularity of a satellite network space environment, and causes queuing phenomena possibly caused by packet-in packets of a large number of resources, thereby causing large delay and low timeliness of resource discovery in the traditional software defined satellite network.
In a double-layer satellite network, a clustering method is used, earth orbit satellites in low latitude areas are used as cluster head nodes, satellite resources of all the nodes in the cluster are collected, and therefore the time for collecting information and converging the resources is saved. However, the method needs to change the cluster head node at variable time, and has higher requirements on right path selection of the controller and real-time performance of the global view; the method of using a certain agent utilizes the concept of a mobile agent in a ground network, is not controlled by a centralized controller in a software-defined satellite network, autonomously moves in each network node, collects resource information of the nodes, and sends the resource information to the centralized controller in real time. However, this mobile agent approach requires autonomous migration through the network, and occupies relatively large computational and memory resources of the node, which is a great expense for the communication capability of the node, and because the mobile agent is independent from the network, it is a great challenge for the global control of the controller.
The characteristics of long satellite link delay, limited bandwidth, high error code, frequent network topology change and the like make it more difficult for the SDN control plane to acquire the full-network information. The challenge of resource discovery problems in a software-defined satellite network is similar to the problem of link discovery, and mainly comprises the judgment of link on-off and packet loss in a space network environment; the link time is prolonged, the convergence of resource information is slow, the timeliness of resource collection is reduced, the SDN control plane is more difficult to obtain accurate and effective whole network resource information, and the routing selection and the resource allocation control of a controller of a software defined satellite network are influenced.
According to the characteristics of various resource discovery methods and the characteristics of the software-defined satellite network, the method utilizes the thought of source routing and optimizes the source routing by the software-defined satellite network to adapt to the problems of delay and timeliness in new space hopes.
Disclosure of Invention
Aiming at the characteristics of large network delay and dynamic topology of a satellite network, the invention provides a resource discovery optimization method for a software-defined satellite network, which is suitable for the development of satellite networking and can optimize the timeliness of resource discovery under the control framework of an SDN.
In order to solve the technical problems, the technical scheme of the invention is as follows: the LLDP-based link discovery optimization method in the software-defined satellite network comprises the following steps:
step 1: after the switches are respectively connected with the controller, the switches perform information interaction with the controller; the information interaction is as follows: the controller sends a characteristic acquisition request message to each switch, and each switch then sends a characteristic reply message to the controller respectively; the characteristic reply message contains all port numbers and port MAC addresses of the switch;
step 2: the controller installs flow tables for all the switches; the flow table is used for telling the switch that an LLDP data packet in a data packet forwarding message is sent out to all ports of the switch after the switch receives the data packet forwarding message sent by the controller, and a source MAC field of the LLDP data packet is set as an MAC address of a sending port;
and step 3: the controller sends a data packet forwarding message to all the switches, and the switch which receives the data packet forwarding message is used as a source switch; the data packet forwarding message comprises an LLDP data packet, and the LLDP data packet comprises a source switch, a source MAC address and a source port number;
and 4, step 4: after receiving the data packet forwarding message, each source switch copies the LLDP data packet and sends the LLDP data packet to all ports of the LLDP data packet, and sets a source MAC address in the LLDP data packet as an MAC address of a sending port;
and 5: after receiving the LLDP data packet sent by the source switch, other switches store the link information to the LLDP data packet and send a data packet receiving message to the controller; the data packet receiving message comprises an LLDP data packet with link information, a destination switch and a destination port number;
step 6: the controller analyzes a source MAC address in the LLDP data packet receiving message and inquires a port number corresponding to the source MAC address to acquire a source switch and a source port number of the link;
and finishing a link discovery process in the software-defined satellite network, and acquiring a global network topological graph of the software-defined satellite network.
The method comprises the steps of calculating the periodicity of a satellite scene, finding out the minimum time interval of software-defined satellite network topology change, and taking the minimum time interval as a link discovery period.
When the port of the switch is changed, the switch sends a port change message to the controller; the controller initiates an independent link discovery to the port immediately after receiving the port change message; the port change comprises port modification, port addition and port deletion; the single link discovery is that the controller sends LLDP packets to the port continuously and separately.
Wherein, step 4 is followed by the step of:
step 41: each switch maintains a port set, adds the port which has sent the LLDP data packet into the port set, and records the packet sending times of each port;
step 42: after a link detection time interval, checking the packet sending times of the ports in the port set; if the packet sending times are more than 0 and less than or equal to the preset times, the port sends the LLDP data packet again, and the packet sending times of the port are added with 1; if the packet sending times are more than the preset times, indicating that the link taking the port as the source end is failed, and deleting the link from the global network topology map of the software defined satellite network; the port set is used for recording the ports which have sent the LLDP data packets and the packet sending times of each port.
A node resource discovery strategy optimization method for a software-defined satellite network is characterized by comprising a link discovery optimization method and a resource collection optimization method.
The resource collection optimization method is based on the centralized control of the OpenFlow switch supporting the source routing and the software-defined satellite network, and reduces or eliminates delay and network resource consumption brought by routing state updating through the source routing.
The resource collection optimization method specifically comprises the following steps:
step 1: the controller selects a path from the global network topology graph by using a route depth algorithm, and the path can traverse the satellite nodes in the network topology as much as possible;
step 2: the controller sends a flow table added with a resource collection matching field to the starting switch; the flow table is used for telling the initial switch, collecting the calculation storage information of the satellite node into a data packet after receiving data packet forwarding information which is sent by the controller and is specially used for resource discovery, and sending the data packet added with the calculation storage information out from a port of a next hop in the path information;
and step 3: the controller sends data packet forwarding information specially used for resource discovery to the initial satellite node; the packet header of the data packet forwarding information contains path information; the path information comprises computing resource information, storage resource information, network link state information, port numbers and port MAC addresses of all satellite nodes in the path;
and 4, step 4: after the initial satellite node receives the data packet forwarding information, matching the data packet forwarding information with a flow table added with a resource collection matching field, if the data packet forwarding information is matched with the flow table added with the resource collection matching field, collecting computing resource information and storage resource information of the satellite node, adding 1 to the node hop count after the collection is finished, and forwarding the data packet after the data collection at a specified port of the satellite node according to path information;
and 5: the initial node forwards the data packet after data collection to the intermediate node;
step 6: the intermediate node collects the computing resource information and the storage resource information of the satellite node, adds 1 to the node hop count after the collection is finished, and forwards the data packet after data collection at the specified port of the satellite node according to the path information;
and 7: and repeating the step 6 until the last satellite node of the path information is executed, and returning all data collection-finished data packets of the path information to the controller by the last satellite node.
Compared with the background technology, the invention has the advantages that:
(1) the method has the advantages that the LLDP protocol is optimized, Packet-out messages are reduced, the link discovery period is prolonged, the link Packet loss and link failure coping strategies are optimized, and the real-time performance and the dynamic performance of updating topology information in the software defined satellite network are improved. In the software defined satellite network, topology changes dynamically, and when links are switched, the delay of judging packet loss and link aging by a controller is reduced.
(2) By utilizing the idea of source routing, a matching domain of OpenFlow is added, the convergence time of a flow table set in the network is reduced, the number of packet-out information collected by resources is reduced, and the load of network resources and a controller is reduced.
Drawings
FIG. 1 is a network physical topology diagram of a two-layer software defined satellite network based on the present invention;
FIG. 2 is a schematic diagram of LLDP-based link discovery according to the present invention;
FIG. 3 is a diagram of link discovery process information interaction of the present invention;
fig. 4 is a flowchart of a link failure packet loss strategy according to the present invention;
FIG. 5 is a diagram of the physical topology of a software defined satellite network according to the present invention;
FIG. 6 is a flow chart of resource collection optimization according to the present invention.
Detailed description of the preferred embodiments
The present invention will be described in further detail with reference to the accompanying drawings and examples for the purpose of facilitating an understanding and practicing of the invention by those of ordinary skill in the art, it being understood that the described examples are only a subset of the examples and are not all examples of the invention.
The technical scheme of the invention comprises two parts. The first part is topology discovery in a satellite network, Packet-out messages are reduced, link discovery period is prolonged, link Packet loss and link failure coping strategies are optimized by optimizing an LLDP protocol, and real-time performance and dynamic performance of topology information updating in a software defined satellite network are improved. If the topology changes dynamically in the software-defined satellite network and the link is switched, the improved protocol is utilized to reduce the delay of judging packet loss and link aging of the controller.
And a second part, utilizing the ideas of optimization and source routing discovered by the link of the first part, after a network topology structure with higher real-time performance is obtained, adding a new domain in a matching domain of an OpenFlow flow table to realize a routing forwarding method of the idea of source routing, forwarding a resource collection packet-out packet, executing corresponding action after matching, and realizing calculation of each node, collection of storage resources and an optimized source routing forwarding strategy. The controller collects node resource information in the network to the greatest extent possible by only sending a packet-out message to the initial node, reduces the sending period and the consumption of network resources under the condition of having a network global view with strong timeliness, and keeps the timeliness of resource data.
The source route is a strategy for carrying out route selection based on a source address, and can realize the function of selectively sending data packets to different destination addresses according to a plurality of different sub-networks or internal network addresses. The Source routing can be divided into two categories, one is Strict Source routing option (Strict Source Route) and the other is Loose Source routing option (lose Source Route).
Strict source routing option: it is specified that IP datagrams are to traverse each router on the path, that no intermediate routers are required between adjacent routers, and that the order of the routers traversed is not modifiable. Loose source routing option: only some 'points' which the IP datagram must pass are given, a complete path is not given, and the routing between routers without direct connection still needs the addressing function supplement of IP software.
It begins with how source routing sends packets to a mobile node attached to a foreign link. IP version 4 defines an option in the IP header: the Loose Source and Record Route Option. This option lists one or more intermediate destination addresses that the packet must pass through before reaching the final destination address.
For example, consider a Source host sending a packet to a destination host, but it also wants the packet to travel through a particular router on the path from the Source to the destination, the Source host placing the "next intermediate destination" address, i.e., the address of that router, in the destination IP address field and the destination host's IP address in the los Source and record route Option, at which time the packet will be routed by the network prefix to the router identified in the destination IP address field.
When that router receives the packet, it checks the alternatives, finds itself as an intermediate destination, and then fetches the address indicated in the lose Source and Record Route Option, i.e. the address of the destination host, and sends the packet to the next hop address to the destination host. Before forwarding the packet, the router records its own IP address in the lose Source and Record Route Option, and actually records the IP address of the port from which it forwarded the packet.
When the data packet arrives at the destination host, the destination host checks the option and finds itself to be the final destination of the packet, so that the destination host delivers the data packet to the higher layer protocol process indicated by the IP protocol field. This Option defined in the IP header also requires that when the destination host replies to the Source host, the lose Source and record Route Option is also included in its packet. Of course, the destination host should contain the source route "backwards". In this example, when the destination host sends a packet to the original Source host, the destination host includes the address of the router as the intermediate destination in the lose Source and Record Route Option.
The detailed technical scheme of the invention is as follows:
the link discovery optimization method based on the LLDP in the software-defined satellite network specifically comprises the steps of reducing Packet-out messages, increasing a link discovery period, and optimizing link Packet loss and link failure coping strategies.
(1) Reduce packet-out messages: the original process that the controller sends a packet forwarding message (packet-out message) to each switch port is reduced to sending a packet-out message to each switch. Achieving this requirement requires two conditions to be met: a. the OpenFlow switch can copy and send one copy of the LLDP data packet from the controller to each port; b. the OpenFlow switch can modify a field in the LLDP packet to identify the port from which the packet originated. The specific term is as follows:
step 1: after SSL/TLS connection is established between each OpenFlow switch and the controller, the controller initiates information interaction of a link discovery process to each OpenFlow switch.
The information interaction process comprises the following steps: the controller sends a characteristic acquisition REQUEST message (OFPT _ featuresrequest message) to the switch, and the switch then replies a characteristic REPLY message (OFPT _ featuresreply message), wherein the OFPT _ featuresreply message contains information such as the port number, the port MAC address, and the like of the OpenFlow switch.
The controller thus maintains mapping information for all OpenFlow switch port numbers and their MAC addresses.
Step 2: the controller installs flow tables for all OpenFlow switches; the flow table tells the switch what kind of packet enters the switch and performs what kind of action (forwarding, returning, discarding, etc.), and when receiving the LLDP packet sent by the controller, sends the packet out from all ports, and sets the LLDP source MAC field as the MAC address of the sending port.
And step 3: the controller sends a Packet forwarding message (Packet-Out message) to all the OpenFlow switches, and the OpenFlow switches receiving the Packet forwarding message are used as source switches; the data packet forwarding message comprises an LLDP data packet, and the LLDP data packet comprises a source switch, a source MAC address and a source port number.
And 4, step 4: after receiving the Packet-Out message, each source switch copies the LLDP Packet and sends it to all its ports, and sets the source MAC in the LLDP Packet as the MAC of the sending port.
In the implementation of the LLDP protocol, after the switch receives the LLDP packet, the flow table matches the LLDP packet, executes the corresponding action, and sends out through all ports of the switch. If no link exists, the LLDP data packet is lost, and the controller cannot receive the packet-in message of the LLDP data packet; if the link exists, the link information is stored in an LLDP packet and returned to the controller through the next-hop switch.
And 5: after receiving the LLDP Packet, the other switches send a Packet-In message to the controller.
Step 6: the controller analyzes a source MAC address in the LLDP data packet and inquires a port number corresponding to the MAC address, so that a source switch and a source port number of the link are obtained; and the destination switch and the destination port number are obtained through metadata In the Packet-In message.
And finishing a link discovery process in the software-defined satellite network, and acquiring a global network topological graph of the software-defined satellite network.
Example (b): as shown in fig. 2, there is a link in Port1 of OpenFlow switch 1 and Port3 of OpenFlow switch 2 in this topology. The specific process of link discovery is shown in fig. 3: a) the OpenFlow switch 1 is connected with a controller, and the controller initiates information interaction of a link discovery process to the OpenFlow switch 1; b) the controller installs a flow table to the OpenFlow switch 1; c) the controller sends a Packet-Out message to the OpenFlow switch 1; d) after receiving the Packet-Out message, the OpenFlow switch 1 sends an LLDP data Packet to all ports thereof, and sets a source MAC in the LLDP as an MAC of the port; e) after receiving the LLDP data Packet, the OpenFlow switch 2 sends the LLDP data Packet to a controller through a Packet-In message; f) the controller analyzes a source MAC address in the LLDP data packet and inquires a port number corresponding to the MAC address, so that a source switch and a source port number of the link are obtained; and the destination switch and the destination port number are obtained through metadata In the Packet-In message.
Eventually the link between switch 1 and switch 2 is discovered. The controller initiates the above operations for each switch, completing link discovery for the entire network.
(2) And (3) enlarging a link discovery period: for satellite networks, the network is often dynamically changing, but has strong periodicity. The satellite scene is calculated through the STK, the periodicity of the satellite scene is researched, the minimum time interval of network topology change is found out to be used as a link discovery period, the link discovery period can be properly increased, and the topology information can be timely updated after the topology change.
Example (b):
in the OpenFlow protocol, when a switch PORT is modified, added, or deleted because a link is disconnected or lost, the switch needs to send a PORT change message (OFPT _ PORT _ STATUS message) to the controller. When a switch port is changed, the LLDP data packets are sent to the port independently and continuously, so that even if the link discovery period of the controller for the whole network is increased, the link change caused by the switch port change can be discovered in time.
(3) The link packet loss and link failure optimization strategy aims at the problem that link discovery and link failure detection are not timely due to link packet loss, and is solved by adding a packet loss detection and quick retransmission mechanism to link discovery.
Example (b):
for example, in fig. 4, the SDN controller initiates a link discovery procedure for all registered switches, and sends a Packet-Out + LLDP message to all switches.
And after the switch receives the Packet-Out + LLDP, forwarding the LLDP to each normally working port, and setting a source MAC field in the LLDP as an MAC address of the port.
Each switch maintains a set ports _ send, and records the port which has sent the LLDP data packet and the packet sending times N.
After the time T _ c (link detection time interval), the number N of LLDP packet sending times of the ports in the ports _ sent set is checked, if N is more than 0 and less than or equal to 5, the LLDP packet is not received within the time T _ c after the LLDP is sent, the LLDP data packet is immediately sent to the port again, and the number of the port packet sending times is added with 1; if N > 5, it means that the LLDP sent from the port has been lost more than 5 times, and it is determined that the link with the port as the source end has failed, and the link is deleted from the topology.
After the link discovery period of T seconds, a new link discovery process is initiated for all the switches.
II, a resource collection optimization method based on a source routing idea in a software defined satellite network comprises the following specific steps:
step 1: after the controller obtains the global network topology view by using the optimized LLDP protocol, a proper path is selected to traverse the satellite nodes in the network as much as possible by using a route depth algorithm.
Step 2: and after the initial switch is connected with the controller and performs information interaction, the initial switch updates a flow table, the flow table tells the switch, and after packet-out information which is specially used for resource discovery and sent by the controller is received, the calculation storage information of the node is collected into a data packet, and the data packet is sent out from a port of the next hop in the sequence.
The originating switch and the controller establish the SSL/TLS connection, the controller sends a featuresrequest message REQUEST to the switch, and the switch then replies a featuresreply message containing information about the port number, port MAC address, etc. of the switch.
The flow table is configured to: the matching field, action and counter, the matching field is used to judge what message; action is used to tell the switch what action to perform.
Example (b): the controller will send a message request to the switch and embed the path information in a packet-out header dedicated to resource discovery. The path information here is represented by a sequence of the hop count of the node and one port number.
The optimized source routing method is used here because the selected path is (X,1,2,4,3,5, Y) among the paths for forwarding the packet, and can also be represented as a queue of port numbers to pass through. In fig. 5, the path from NODE X to NODE Y can be represented as (1,2,2,2,2,3), and this queue means that the data packet is sent from port1 of the start NODE, and after reaching the next hop NODE, the data packet is sent from port 2 to the next hop NODE, and so on, the port number and hop count sent by the data packet represent the path through which the whole data flows. In fig. 5, the route state information represented by the port number and the hop count is generated using the optimized source route method to represent the path (1,2,2,2,2,3) from NODE X to NODE Y, replacing the original route information represented by the switch flow table.
Different from the original one-by-one issuing mode, the source routing method only needs to issue the packet header with the updated routing state information to the starting NODE, and the source routing optimization method reduces the cost of sending the updated information to the intermediate NODEs NODE 1, NODE 2, NODE3, NODE 4 and NODE 5 and also eliminates the time for waiting convergence due to the issued state information.
And step 3: and the controller transmits packet-out information specially used for resource discovery to the initial node.
And 4, step 4: after receiving the packet-out information, the initial satellite node is matched with the flow table added with the resource collection matching domain, and if the packet-out information of the collected resources is matched, the Instructions Set in the flow table can execute a Set series of actions;
and executing Action: and collecting data for the node, adding 1 to the hop count of the node in the packet header after the data is collected, and forwarding the data at the appointed port of the node according to the path information in the packet header.
And 5: the originating node forwards the data-collected packet to the intermediate node.
Step 6: and the intermediate node executes corresponding operation, finally reaches the last node of the port sequence, and returns a data packet to the controller after executing the Action.
Example (b): in fig. 5, the route state information represented by the port number and the hop count is generated using the optimized source route method to represent the path (1,2,2,2,2,3) from NODE X to NODE Y, replacing the original route information represented by the switch flow table. The information includes the information of computing resource information, storage resource information, network link state information, port number of the switch, port MAC address and the like of all nodes in the path. And the controller sends a packet-out packet to the initial node at regular time according to the detection period of the optimized link failure in the LLDP, so that the timeliness of the resource data is maintained.
And III, optimizing a node resource discovery strategy aiming at the software defined satellite network, wherein the optimization comprises two parts of link discovery optimization and resource collection optimization.
The link discovery optimization is based on an LLDP protocol, Packet-out messages are reduced, a link discovery period is increased, link Packet loss and link failure coping strategies are optimized, and the real-time performance and the dynamic performance of topology information updating in a software defined satellite network are improved.
The resource collection method is optimized based on the OF switch supporting source routing and the centralized control OF the software-defined satellite network, and reduces and eliminates delay and network resource consumption caused by updating OF routing states through the function OF the source routing.
It should be understood that the above-mentioned embodiments are merely preferred embodiments of the present invention, and not intended to limit the present invention, and 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 (4)

1. A node resource discovery strategy optimization method aiming at a software-defined satellite network comprises a link discovery optimization method based on LLDP, and is characterized by further comprising a resource collection optimization method; the resource collection optimization method is based on the centralized control of an OpenFlow switch supporting source routing and a software-defined satellite network, reduces or eliminates delay and network resource consumption brought by routing state updating through the source routing, and comprises the following steps:
step 1: the controller selects a path from the global network topology graph by using a route depth algorithm, and the path can traverse the satellite switching nodes in the network topology as much as possible;
step 2: the controller sends a flow table added with a resource collection matching field to the initial satellite switching node; the flow table is used for telling the initial satellite switching node, collecting the calculation storage information of the satellite switching node into a data packet after receiving data packet forwarding information which is sent by the controller and is specially used for resource discovery, and sending the data packet added with the calculation storage information out from a port of a next hop in the path information;
and step 3: the controller sends data packet forwarding information specially used for resource discovery to the initial satellite switching node; the packet header of the data packet forwarding information contains path information; the path information comprises computing resource information, storage resource information, network link state information, port numbers and port MAC addresses of all satellite nodes in the path;
and 4, step 4: after the initial satellite switching node receives the data packet forwarding information, matching the data packet forwarding information with a flow table added with a resource collection matching field, if the data packet forwarding information is matched with the flow table added with the resource collection matching field, collecting computing resource information and storage resource information of the satellite switching node, adding 1 to the node hop count after the collection is finished, and forwarding the data packet after the data collection at a specified port of the satellite switching node according to the path information;
and 5: the initial satellite switching node transmits the data packet after data collection to the intermediate satellite switching node;
step 6: the intermediate satellite switching node collects the calculation resource information and the storage resource information of the satellite switching node, adds 1 to the node hop count after the collection is finished, and forwards the data packet after data collection at the specified port of the intermediate satellite switching node according to the path information;
and 7: repeating the step 6 until the last satellite switching node of the path information is executed, and returning all data of the path information to the controller by the last satellite switching node to obtain a data packet after all data collection is finished;
the link discovery optimization method based on the LLDP comprises the following steps:
step 1: after the switches are respectively connected with the controller, the switches perform information interaction with the controller; the information interaction is as follows: the controller sends a characteristic acquisition request message to each switch, and each switch then sends a characteristic reply message to the controller respectively; the characteristic reply message contains all port numbers and port MAC addresses of the switch;
step 2: the controller installs flow tables for all the switches; the flow table is used for telling the switch that an LLDP data packet in a data packet forwarding message is sent out to all ports of the switch after the switch receives the data packet forwarding message sent by the controller, and a source MAC field of the LLDP data packet is set as an MAC address of a sending port;
and step 3: the controller sends a data packet forwarding message to all the switches, and the switch which receives the data packet forwarding message is used as a source switch; the data packet forwarding message comprises an LLDP data packet, and the LLDP data packet comprises a source switch, a source MAC address and a source port number;
and 4, step 4: after receiving the data packet forwarding message, each source switch copies the LLDP data packet and sends the LLDP data packet to all ports of the LLDP data packet, and sets a source MAC address in the LLDP data packet as an MAC address of a sending port;
and 5: after receiving the LLDP data packet sent by the source switch, other switches store the link information to the LLDP data packet and send a data packet receiving message to the controller; the data packet receiving message comprises an LLDP data packet with link information, a destination switch and a destination port number;
step 6: and the controller analyzes the source MAC address in the LLDP data packet receiving message, inquires the port number corresponding to the source MAC address and acquires the source switch and the source port number of the link.
2. The method of claim 1 for node resource discovery policy optimization for software defined satellite networks, wherein: and calculating the periodicity of the satellite scene, finding out the minimum time interval of the software-defined satellite network topology change, and taking the minimum time interval as a link discovery period.
3. The method of claim 2, wherein the node resource discovery strategy for software defined satellite networks is optimized by: when the port of the switch is changed, the switch sends a port change message to the controller; the controller initiates an independent link discovery to the port immediately after receiving the port change message; the port change comprises port modification, port addition and port deletion; the single link discovery is that the controller sends LLDP packets to the port continuously and separately.
4. The method of claim 1 for node resource discovery policy optimization for software defined satellite networks, wherein: the link discovery optimization method based on the LLDP further comprises the following step 4:
step 41: each switch maintains a port set, adds the port which has sent the LLDP data packet into the port set, and records the packet sending times of each port;
step 42: after a link detection time interval, checking the packet sending times of the ports in the port set; if the packet sending times are more than 0 and less than or equal to the preset times, the port sends the LLDP data packet again, and the packet sending times of the port are added with 1; if the packet sending times are more than the preset times, indicating that the link taking the port as the source end is failed, and deleting the link from the global network topology map of the software defined satellite network; the port set is used for recording the ports which have sent the LLDP data packets and the packet sending times of each port.
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