CN108667728B - Software defined network routing method based on flow table entry multiplexing mechanism - Google Patents
Software defined network routing method based on flow table entry multiplexing mechanism Download PDFInfo
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- CN108667728B CN108667728B CN201810399263.2A CN201810399263A CN108667728B CN 108667728 B CN108667728 B CN 108667728B CN 201810399263 A CN201810399263 A CN 201810399263A CN 108667728 B CN108667728 B CN 108667728B
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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
- H04L45/24—Multipath
- H04L45/245—Link aggregation, e.g. trunking
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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
- H04L45/22—Alternate routing
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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
- H04L45/38—Flow based routing
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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
- H04L45/50—Routing or path finding of packets in data switching networks using label swapping, e.g. multi-protocol label switch [MPLS]
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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
- H04L45/74—Address processing for routing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/12—Avoiding congestion; Recovering from congestion
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/41—Flow control; Congestion control by acting on aggregated flows or links
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/46—Interconnection of networks
- H04L12/4641—Virtual LANs, VLANs, e.g. virtual private networks [VPN]
Abstract
The invention discloses a software defined network routing method based on a flow table item multiplexing mechanism, which comprises the following steps: s1, starting a processing thread; s2, selecting a working path; s3, selecting a next target working path; s4, calculating a current optimization target and a next optimization target; s5, generating an exponential distribution timer and starting countdown; s6, judging whether reset information is received; s7, updating the latest feasible solution and the latest current optimization target; s8: judging whether the countdown is finished or not; s9, recording the current optimization target and the duration of the current optimization target; s10, obtaining the latest feasible solution and the latest current optimization target, broadcasting reset information and resetting a timer; and S11, judging whether all the current optimization targets are stably converged to the latest current optimization target. The invention solves the problems of insufficient flow aggregation capability, easy link congestion and low service quality caused by long-distance flow in the prior art.
Description
Technical Field
The invention belongs to the technical field of software defined networks, and particularly relates to a software defined network routing method based on a flow table item multiplexing mechanism
Background
With the high-speed development of the internet, the scale of a traditional network is continuously enlarged, the problems of the internet in the aspects of service quality assurance, safety, high-efficiency management and control capability and the like are increasingly prominent, and a Software-defined network (SDN) is used as a novel network architecture for configuring flow table entries in a switch to forward flow, has the characteristics of flexible structure, centralized configuration and rapid network service deployment, and can well solve the problems. The control layer of the SDN is separated from the forwarding layer, the implementation of the forwarding layer depends on flow table entries uniformly configured for the control layer, and the flow table entries are stored in a Ternary Content Addressable Memory (TCAM) in the SDN switch, and the TCAM supports high-speed parallel search in a wildcard mode. However, although TCAM performs well in packet processing, it is expensive and power intensive in hardware. For this reason, how to minimize the number of flow entries while processing flows in the network becomes a very valuable issue.
The current methods for reducing Flow table entry are office and Flow Aggregation (FA):
the office presets a default path for all streams from the same source. The flow is then deflected from the default path to its destination according to the deflection policy.
In the FA, all flows arriving at the same destination are routed over the existing path to aggregate the flow entry.
The prior art has the following problems:
(1) the drawback of office is that the traffic is concentrated on the default path, the link is easily congested, and the deflection on the default path easily causes traffic to be far away, resulting in degradation of quality of service QoS, and thus causing serious network delay and congestion. In addition, only flows that traverse the default path can actually be aggregated, also limiting the aggregation capability of the flows.
(1) In the FA, because the FA is a tree-based route, nodes and links that do not belong to the tree are not available, which also causes links to be easily congested and traffic may be far away so that quality of service QoS is degraded, thereby causing network delay and congestion to be severe.
In summary, the prior art has the problems of insufficient flow aggregation capability, easy link congestion and low service quality caused by traffic wandering.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a software defined network routing method based on a flow table item multiplexing mechanism, which has the advantages of flow table item quantity reduction, high survivability, smooth link and high service quality, and solves the problems of insufficient flow aggregation capability, easy link congestion and low service quality caused by far flow in the prior art.
In order to achieve the purpose of the invention, the invention adopts the technical scheme that:
a software defined network routing method based on a flow table entry multiplexing mechanism comprises the following steps:
s1: starting a corresponding processing thread aiming at each service flow in the software defined network, and selecting an alternative path for the service flow in the software defined network;
s2: according to a flow table item multiplexing mechanism, each thread randomly selects an available path from the alternative paths to serve as a current working path of the corresponding service flow; then, calculating a current optimization target according to a feasible solution consisting of the current working path;
s3: randomly selecting an available and unoccupied path from the alternative paths as a next target working path;
s4: calculating a next optimization target according to a next target solution consisting of a next target working path;
s5: generating an exponentially distributed timer and starting to count down;
s6: judging whether reset information is received, if so, turning to the step S7, otherwise, turning to the step S8;
s7: updating the latest feasible solution and the latest current optimization target according to the broadcasted reset information, keeping the next target working path unchanged, and entering the step S4;
s8: judging whether the countdown is finished, if so, turning to the step S9, otherwise, turning to the step S6;
s9: recording the current optimization target and the duration thereof, and entering step S11;
s10: assigning the next target working path to the current working path to obtain the latest current working path, combining to obtain the latest feasible solution, assigning the next optimization target to the current optimization target to obtain the latest current optimization target, broadcasting reset information and resetting a timer, and entering step S3;
s11: and combining all the current optimization targets obtained in the step S9, judging whether all the current optimization targets are stably converged to the latest current optimization target by a mapping analysis method according to the duration, if so, taking the latest feasible solution corresponding to the latest current optimization target as an optimal routing scheme, and ending routing, otherwise, entering a step S10.
Further, in step S2, the flow table entry multiplexing mechanism uses multiple traffic flows passing through the same path as an aggregated traffic flow, and uses the coding of the virtual local area network as a forwarding label.
Further, in step S2, each thread randomly selects another available path from the alternative paths as the current backup path of the corresponding traffic flow.
Further, in step S3, another available and unoccupied path is randomly selected as the next backup path.
Further, in step S4, the current optimization target is the total number of flow entries in the current network corresponding to the currently feasible solution, and the next optimization target is the total number of flow entries in the next network corresponding to the next target solution.
Further, in step S5, the calculation formula of the average value of the timer is:
Tf＝(1/|AP|)exp(τ-(1/2)β(ucf-ucf'))
in the formula, TfIs the average value of the timer; AP is the path length; u. ofcfIs the current optimization objective; u. ofcf' is the next optimization objective,. tau.is the overflow prevention constant, and β is a trade-off factor.
Further, in step S10, the reset information includes the latest feasible solution and the latest current optimization goal.
The beneficial effect of this scheme does:
the method can further reduce the total number of flow table entries and has better network performance, a plurality of service flows passing through the same path are aggregated into one by using the VLAN ID as a tag, the number of the flow table entries is reduced, the service flows can be aggregated at any time and can be decoupled at any time, the flow aggregation capability is improved, the practicability and the survivability of the software defined network are further improved, the multiplexing mechanism of the flow table entries in the method is applied to the protection path of the software defined network, and the number of spare flow table entries can be reduced; the method effectively expands the range of service flow aggregation, greatly compresses the number of required working and standby flow table items, thereby reducing the number of required memories in the software defined network switch, keeping the smooth of links in the software defined network, avoiding traffic from being far away and improving the service quality of the software defined network.
Drawings
FIG. 1 is a flow chart of a software defined network routing method based on a flow table entry multiplexing mechanism;
FIG. 2 is a schematic diagram of an embodiment of a flow entry multiplexing mechanism;
fig. 3 is a schematic diagram of an embodiment of software-defined network routing based on a flow table entry multiplexing mechanism.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
In the embodiment of the present invention, a software-defined network routing method based on a flow table entry multiplexing mechanism, as shown in fig. 1, includes the following steps:
s1: starting a corresponding processing thread aiming at each service flow in the software defined network, and selecting a plurality of alternative paths for the flow in the software defined network;
s2: according to a flow table item multiplexing mechanism, a plurality of service flows passing through the same path are used as an aggregated service flow, and the code of a virtual local area network is used as a forwarding label; randomly selecting an available path from the alternative paths by each thread to serve as a current working path of the corresponding service flow, and calculating a current optimization target according to a feasible solution consisting of the current working path; each thread randomly selects another available path from the alternative paths as a current backup path of the corresponding service flow;
s3: randomly selecting an available and unoccupied path from the alternative paths as a next target working path; randomly selecting another available and unoccupied path as a next backup path;
s4: calculating a current optimization target according to a feasible solution formed by the current working path selected by each service flow, and calculating a next optimization target according to a next target solution formed by a next target working path; the current optimization target is the total number of flow table items in the current network corresponding to the current feasible solution, and the next optimization target is the total number of flow table items corresponding to the next target solution formed by the next target working paths of all the service flows after only the working path of the service flow corresponding to the thread is changed into the next target path;
s5: generating an exponentially distributed timer and starting to count down;
the average value of the timer is calculated by the formula:
Tf＝(1/|AP|)exp(τ-(1/2)β(ucf-ucf'))
in the formula, TfIs the average value of the timer; AP is the path length; u. ofcfIs the current optimization objective; u. ofcf' is next optimization objective, [ tau ] is overflow prevention constant, [ β ] is a trade-off factor;
s6: judging whether reset information is received, if so, turning to the step S7, otherwise, turning to the step S8;
s7: updating the latest feasible solution and the latest current optimization target according to the broadcasted reset information, keeping the next target working path unchanged, and entering the step S4;
s8: judging whether the countdown is finished, if so, turning to the step S9, otherwise, turning to the step S6;
s9: recording the current optimization target and the duration thereof, and entering step S11;
s10: assigning the next target working path to the current working path to obtain the latest current working path, combining to obtain the latest feasible solution, assigning the next optimization target to the current optimization target to obtain the latest current optimization target, broadcasting reset information and resetting a timer, wherein the reset information comprises the latest feasible solution and the latest current optimization target, and entering step S3;
s11: and combining all the current optimization targets obtained in the step S9, judging whether all the current optimization targets are stably converged to the current optimization targets through a mapping analysis method according to the duration, if so, taking the latest feasible solution corresponding to the latest current optimization target as an optimal routing scheme, and ending routing, otherwise, entering a step S10.
In the embodiment of the present invention, as shown in fig. 2, there are 3 service flows in the network: h1-h4, h2-h6 and h3-h 5. Path A-B-C-D is defined as the Multiplex Segment (MS). Since the three traffic streams all pass through the multiplex section, they can be aggregated into one traffic stream on the multiplex section. In a standard matching field of the SDN, an encoded VLAN ID of one of the virtual local area networks is selected as a tag of the aggregated traffic flow (the VLAN ID value is set to 2), and the priority of this traffic flow entry is set to Low. Commercial-type software defined network SDN switches, such as Pica 8 switches, always support the operation of setting VLAN IDs for traffic flows. In fact, any VLAN ID value may be used as a tag for the aggregate traffic flow as long as this VLAN ID value is not used in the network. Since the central controller can keep track of the information of all traffic flows in the network, it is easy to find a suitable VLAN ID value. The priority of the aggregated service flow table entry is lower than that of a normal service flow table entry (the matching domain is source destination address matching), so that the service flows can be aggregated or deaggregated flexibly on the multiplexing section. As can be seen from fig. 2, the service flow entry multiplexing method significantly reduces the number of service flow entries.
The protection mechanism of the software defined network SDN can guarantee the survivability of traffic flow to link failure. Backup service flow table entries are always configured in advance in the network in the protection mechanism of the SDN. Therefore, after the link failure occurs, the switch will automatically divert the affected traffic to the backup path without recalculating the restoration path through the controller and issuing the corresponding traffic entry to the switch. However, with this method, a large amount of space for backup traffic flow entries needs to be reserved in the network, which may exceed the resource limit of the TCAM memory.
As shown in fig. 3, the method for multiplexing the service flow table entry is extended to SDN protection. Assume that there is a multiplexed segment a-B-C-D (VLAN ID value 2) in the network. The backup paths for traffic flows h3-h7 are aggregated at switch B and de-aggregated at switch D. By using the method of multiplexing the service flow table entry, backup service flow table entries are not needed to be installed on the switch B and the switch C.
The method can further reduce the total number of flow table entries and has better network performance, a plurality of service flows passing through the same path are aggregated into one by using the coded VLAN ID of the virtual local area network as a tag, the number of the flow table entries is reduced, the service flows can be aggregated at any time and can be decoupled at any time, the practicability and the survivability of the software defined network are improved, and the number of standby flow table entries can be reduced in a protection path of the software defined network; the method effectively expands the range of service flow aggregation, greatly compresses the number of required working and standby flow table items, thereby reducing the number of required memories in the software defined network switch, and can keep the smooth of links in the software defined network, thereby improving the service quality of the software defined network; the problems of insufficient flow aggregation capability, easy link congestion and low service quality caused by far flow existing in the prior art are solved.
Claims (6)
1. A software defined network routing method based on a flow table entry multiplexing mechanism is characterized by comprising the following steps:
s1: starting a corresponding processing thread aiming at each service flow in the software defined network, and selecting an alternative path for the service flow in the software defined network;
s2: according to a flow table item multiplexing mechanism, each thread randomly selects an available path from the alternative paths to serve as a current working path of the corresponding service flow; then, calculating a current optimization target according to a feasible solution consisting of the current working path;
s3: randomly selecting an available and unoccupied path from the alternative paths as a next target working path;
s4: calculating a next optimization target according to a next target solution consisting of a next target working path;
s5: generating an exponentially distributed timer and starting to count down;
s6: judging whether reset information is received, if so, turning to the step S7, otherwise, turning to the step S8;
s7: updating the latest feasible solution and the latest current optimization target according to the broadcasted reset information, keeping the next target working path unchanged, and entering the step S4;
s8: judging whether the countdown is finished, if so, turning to the step S9, otherwise, turning to the step S6;
s9: recording the current optimization target and the duration thereof, and entering step S11;
s10: assigning the next target working path to the current working path to obtain the latest current working path, combining to obtain the latest feasible solution, assigning the next optimization target to the current optimization target to obtain the latest current optimization target, broadcasting reset information and resetting a timer, and entering step S3;
s11: combining all the current optimization targets obtained in the step S9, judging whether all the current optimization targets are stably converged to the latest current optimization target or not through a mapping analysis method according to the duration, if so, taking the latest feasible solution corresponding to the latest current optimization target as an optimal routing scheme, and finishing routing, otherwise, entering a step S10;
in step S2, the flow table entry multiplexing mechanism uses multiple service flows passing through the same path as an aggregated service flow, and uses the code of the virtual local area network as a forwarding label.
2. The method as claimed in claim 1, wherein in step S2, each thread randomly selects another available path from the alternative paths as the current backup path of the corresponding traffic flow.
3. The method as claimed in claim 1, wherein in step S3, another available and unoccupied path is randomly selected as the next backup path.
4. The method as claimed in claim 1, wherein in step S4, the current optimization goal is a total number of flow entries in the current network corresponding to the current feasible solution, and the next optimization goal is a total number of next flow entries corresponding to the next target solution.
5. The method for software-defined network routing based on flow entry multiplexing mechanism as claimed in claim 1, wherein in step S5, the calculation formula of the average value of the timer is:
Tf＝(1/|AP|)exp(τ-(1/2)β(ucf-ucf'))
in the formula, TfIs the average value of the timer; AP is the path length; u. ofcfIs the current optimization objective; u. ofcf'For the next optimization objective,. tau.is the overflow prevention constant, and β is a trade-off factor.
6. The method as claimed in claim 1, wherein in step S10, the reset information includes the latest feasible solution and the latest current optimization goal.
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| CN106656809A (en) * | 2015-11-03 | 2017-05-10 | 中国电信股份有限公司 | Flow table aggregation method, controller, network element and system |
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