CN103023781A

CN103023781A - Shortest path tree and spanning tree combined energy-saving routing method

Info

Publication number: CN103023781A
Application number: CN2012105399339A
Authority: CN
Inventors: 李丹; 余逸荣
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2012-12-13
Filing date: 2012-12-13
Publication date: 2013-04-03
Anticipated expiration: 2032-12-13
Also published as: CN103023781B

Abstract

The invention discloses a shortest path tree and spanning tree combined routing method and belongs to the technical field of network topology. The method is characterized in that on the basis of a standard link state routing protocol, a dormant state is added to each link which is connected with a router node in a network, a shared spanning tree is selected on a given network topology, links on the spanning tree are in a working state all the time so as to guarantee network connectivity, other links which are not on the spanning tree enter into dormant states if no flow passes, each router stores a shortest path routing list of the whole network path and a routing list of a corresponding spanning tree, as for a data packet, an ingress router determines that the data packet uses a path therein according to current link loads, a label identification is added, and a non ingress router selects a corresponding routing list according to a label to perform forwarding.

Description

The energy-saving routing method that shortest path tree is combined with spanning tree

Technical field

GreenNet

Background technology

GreenNet is an important directions of current network research, and the huge energy consumption problem of the Internet and poor efficiency energy use problem day by day to highlight.In order more effectively to utilize the energy, reduce energy dissipation, utilize the link dormancy mechanism to realize that the research of network energy-saving is obtaining academia and industrial quarters is more and more paid close attention to.In general Internet Service Provider (ISP) network; in order to tackle flow summit and potential link failure; in the networking and upgrading period; Virtual network operator usually can be disposed redundant link and increase the redundant link bandwidth; and offered load is not high most in the actual daily network time; cause the link average utilization on the low side, and router power consumption is compared the full load running status and be there is no and reduce.These factors all can cause the energy dissipation problem in the network.

Link-state routing protocol is Routing Protocol in the territory of commonly using now, the path that the router of this agreement calculates is shortest path, owing to do not consider the factors such as energy consumption at the beginning of this Protocol Design, caused the utilance of ISP network uplink low, the problem of a large amount of energy dissipations.The object of the invention is to improve traditional standard Link State route, adopt the power-saving mechanism of spanning tree (ST:spanning tree) and shortest path tree (SPT:shortest path tree) combination, flow is gathered on the least possible link, and all the other links enter the idle sleep state and reach energy-conservation.

Summary of the invention

The object of the invention is to two kinds of different shortest path paths and novel energy-conservation line state method for routing of spanning tree path configuration, flow is gathered on the spanning tree, so that more multilink enters resting state, when realizing energy-conservation purpose, improve the average link utilance, reduce energy dissipation.

The invention is characterized in:

1. realize according to the following steps successively on the network topology:

Step (1), network topology initialization: on the basis of standard link-state routing protocol, to increasing resting state on every link that wherein each router node connects;

Step (2), each router node periodically detects the loading condition of all direct connected links, use the LSA mechanism LSA of open type shortest path priority protocol OSPF itself that link load information is flooded on the network topology together with link-state information, so that each router node on the described network topology all has identical network topological information and link load information;

Step (3), each router node according to the result who obtains from step (2) calculate own on the network topology shortest path and the spanning tree path of other arbitrary router nodes, generate routing table, and the result of calculation of all-router node is consistent;

Step (4), each router node on the described network topology is according to the situation of the path uplink load of data flow process, press destination address and select a suitable path for each bar data flow, select corresponding routing table, and selection result is added to the head of data message as label, transmit by " destination address+label " again, in routing table, determine route next jump according to label;

Step (5), receive the message with label of being transmitted by upstream router when the downstream router node after, select down hop according to label, transmit by the form of " destination address+label ";

Step (6), after the core router node receives a message, check the link of transmitting end, if it is normal to transmit Duan Duanlu, then normally transmit by label, if when finding that the link of forwarding end is in resting state, need to be this dormancy link wakeup, the label that with the tag modification of this datagram is again spanning tree is transmitted, until arrive the purpose router.

2. the shortest path tree according to claim 1 energy-saving routing method of being combined with spanning tree, it is characterized in that, on described spanning tree, construct again one for the actual online subgraph that adopts, each router node on it is on some links of described spanning tree, lost efficacy to prevent single-link in the limit that also will comprise minimum number.

The thinking of method proposed by the invention is: on the basis of standard link-state routing protocol, every link that router node is connected increases resting state.Formulate a connected subgraph in given network topology, the link on the connected subgraph is in running order all the time, if other outer nodes of connected subgraph continue for some time do not have flow through enter resting state.Router compiles flow on the spanning tree by making up a spanning tree at connected subgraph, so that the link that enters dormancy is more mainly with reaching energy-conservation effect.

The advantage of method proposed by the invention is:

1. employing distributed algorithm, each ingress router is independently made a strategic decision according to the link load information of collecting;

2. can change offered load fast and make real-time response, flow switches between shortest path tree and spanning tree fast;

3. between network energy-saving efficient and offered load elasticity, obtain good balance.

Description of drawings

Fig. 1. Global Topological and spanning tree/connected subgraph,

Fig. 1 .1 Global Topological,

Fig. 1 .2 spanning tree/connected subgraph (thick line part).

Fig. 2. " destination address+label " transmits schematic diagram.

Fig. 3. label replacement schematic diagram.

Fig. 4. the Routing Protocol flow chart,

Fig. 4 .1 Path selection flow chart,

Fig. 4 .2 package forward flow chart.

Embodiment

Shown in Fig. 1 .1, an extreme case of energy-saving efficiency and network resilience contradiction is exactly all in running order when all links, and at this time the network energy consumption is maximum, but simultaneously also the most reliable and high resilience can be tackled burst flow spike and link failure.Another extreme case sees that Fig. 1 .2 is that all links on a connected subgraph that comprises all nodes are in running order, and other links all are in resting state.If online subgraph is taken as a spanning tree, then this time network energy-saving most effective, but also be most fragile simultaneously.The thorough energy-saving routing protocol of consideration should not only be considered energy-saving efficiency, should consider network resilience and global network performance simultaneously comprehensively.In addition, because Link State switches the real-time traffic demand that is based on, our energy-saving routing protocol needs and can make a policy fast, and keeps consistency in complete topological scope.Our the energy-saving routing protocol main thought of research is according to the actual traffic load situation of network, realizes level and smooth as far as possible switching between two kinds of extreme cases.When traffic demand is low, utilize the link on the spanning tree to transmit flow as far as possible, make the fractional energy savings maximization; When traffic demand increases, little by little flow is moved on the Global Topological from spanning tree, waken up necessary link to keep network resilience and performance, until all flows are all chosen shortest path, at this time agreement converges to the situation of OSPF automatically.The focus of the energy-saving routing protocol that we study is to make packet loss and out of order minimizing so that such switching is level and smooth as much as possible, to such an extent as to minimize owing to the energy-conservation impact that brings concerning upper-layer protocol is used.

Workflow:

I) at first each router periodically detects the loading condition of direct connected link, and this link load information is flooded to whole network together with link-state information, can use the LSA inundation mechanism of OSPF itself to realize.

Ii) so far, each router all has identical network topological information and link load information on the topology, pass through topology information, router can calculate oneself to shortest path and the spanning tree path of other arbitrary nodes of network, and because the identical topology of using, unified algorithm so all-router calculating path result keeps consistency, satisfies optimum minor structure characteristic.

Iii) then, each ingress router for each the bar stream take it as entrance is selected suitable path, and adds selection result to the data message head as label according to the path uplink load state of data flow process, then transmit according to " destination address+label ", see Fig. 2.

Iv) receive the tape label message of upstream forwarding when the downstream node, directly transmit according to " destination address+label ".

V) when running into when transmitting the port link and being in resting state, for the continuity that guarantees to flow, during link was waken up, forward node can reset to the label of packet along the label of spanning tree and transmit in the path, no longer carry out label after the link wakeup and reset, see Fig. 3.

For improving the reliability of network topology, the actual online subgraph that adopts should be to increase to a certain extent redundancy on the basis of spanning tree, a kind of feasible scheme be seek such subgraph so that each node on some rings, the limit that comprises simultaneously minimal number, so online subgraph can successfully manage the situation that single-link lost efficacy.

We test 3 real topologys, find that the power-saving mechanism of spanning tree and shortest path tree combination can be saved 20% ~ 50% ply-yarn drill consumed energy when link utilization is low, illustrate that the present invention has reached the purpose of expection.

Claims

1. the shortest path tree energy-saving routing method of being combined with spanning tree is characterized in that, realizes according to the following steps successively on the network topology: