CN100527745C

CN100527745C - A LSA passive collection method under the OSPF full adjacent connection condition

Info

Publication number: CN100527745C
Application number: CNB2006101716527A
Authority: CN
Inventors: 何坤明; 毕经平; 李忠诚
Original assignee: Institute of Computing Technology of CAS
Current assignee: Institute of Computing Technology of CAS
Priority date: 2006-12-31
Filing date: 2006-12-31
Publication date: 2009-08-12
Anticipated expiration: 2026-12-31
Also published as: CN101009702A

Abstract

The disclosed LSA passive collection method on full-adjoin condition of OSPF comprises: initiating the system execution environment of LSA collection device; initiating the virtual thread schedule center in LSA collection device, determining the schedule strategy; acquiring the network interface information of LSA collection device; reading configuration file, executing corresponding operation, and registering relative virtual thread in the center; selecting the maximal IP address value from all interfaces running OSTF protocol as the LSA collection device mark; scheduling by the center, executing obtained virtual thread, building adjoin relation with some neighbor according to OSPF protocol and collecting LSA information synchronously. This invention overcomes the compatibility conflict of full-adjoin and passive-type.

Description

LSA passive collection method under a kind of OSPF full adjacent condition

Technical field

The present invention relates to technical field of the computer network, LSA passive collection method under particularly a kind of OSPF full adjacent condition.

Background technology

OSPF (Open Shortest Path First, Open Shortest Path First) agreement is an Interior Gateway Protocol (Interior Gateway Protocol, be called for short IGP), be used for decision-making route in single autonomous system (Autonomous System is called for short AS).OSPF sets up the LSA database by the state of the interface of announcement operation ospf protocol between the router, generates shortest path tree, and each ospf router uses these shortest path tree structure routing tables.Ospf protocol is mapped to its defined four kinds of abstract network type to existing real network type, is respectively point-to-point (Point-to-Point) network type, puts multiple spot (Point-to-MultiPoint) network type, NBMA (Non-Broadcast MultiAccess) network type, broadcast multipath access (BroadcastMultiAccess) network type.

The configurable item of ospf router interface includes the priority of interface, the transmission cycle of Hello bag etc.Wherein, the priority of ospf router interface is mainly used in choosing of DR, BDR, and the transmission cycle of Hello bag mainly is the transmitting time span of configuration Hello bag.Use LSA (Link StateAdvertisement is called for short LSA) to exchange link-state information separately between the ospf router, and an information stores that obtains is in the LSA database.Each ospf router independently uses the route of SPF algorithm computation to each purpose network prefix.

Network topology, route are calculated in the network for convenience, need to gather the LSA information between router.Prior art based on the mutual LSA acquisition method of ospf protocol mainly contains two kinds: one, full adjacent, active access module; Two, part adjacency, passive drainage pattern.Respectively the pluses and minuses of these two kinds of prior aries are described below.

One, full adjacent, active access module

The thinking of this pattern be with collector as a couple in router, thereby collect LSA information.The shortcoming of this pattern is that the syntople between collector and the neighbor router will be declared in the network, thereby has influence on network topology, route calculating, finally influences forwarding of data on the network.

Two, part adjacency, passive drainage pattern

The thinking of this pattern is to set up the part syntople between collector and neighbor router, thereby makes the link between collector and the neighbor router can not have influence on network topology, route calculating and network data forwarding, has realized the purpose of passive collection.To be collector describe the packet switch stage at ospf database to specific practice sends an ospf database that contains false LSA head descriptor and describe bag, neighbor router is after receiving this ospf database that contains false LSA head descriptor description bag, through handling, with the request of sending to this false LSA information, collector can not done any response to this request this moment, thereby the neighbor state that makes neighbor router remains on this labile state of NSM_Loading, forms part in abutting connection with pattern.

The shortcoming of this pattern is;

1, part is after foundation, and the neighbor state of neighbor router is in the NSM_Loading state always, and this is undefined in the ospf protocol standard, and its result is unpredictalbe on different routers is realized;

2, to be in the neighbor router of NSM_Loading be the LSA information that can't discharge MaxAge to neighbor state, operation along with network, this MaxAge LSA will be poly-more many more, finally cause neighbor router because the memory consumption machine of totally delaying, therefore this pattern needs periodic this part adjacency that discharges, so that neighbor router is cancelled the LSA that the back discharges MaxAge in this part adjacency, but this also makes the integrality of LSA information gathering be affected simultaneously;

3, be in the NSM_Loading state neighbor router will with 5 seconds frequencies once to the collector request should vacation LSA information, this will cause collector and unnecessary cpu resource consumption and the unnecessary link bandwidth consumption of neighbor router.

Further specifying of above-mentioned pattern asked for an interview list of references 1: " An OSPF Topology Server:Designand Evaluation.”

Summary of the invention

The objective of the invention is to overcome in the existing LSA acquisition method contradiction that can not take into account full adjacent and passive type, thereby a kind of acquisition method of LSA information is provided.

To achieve these goals, the invention provides LSA passive collection method under a kind of OSPF full adjacent condition, may further comprise the steps:

Step 1), system's execution environment of LSA collector is done initialization operation;

Step 2), initialization operation is done by the virtual thread control centre in the LSA collector, determine the scheduling strategy of virtual thread;

Step 3), obtain the network interface information on the LSA collector;

Step 4), read configuration file, carry out operation accordingly, and register corresponding virtual thread to the virtual thread control centre; Comprise:

Step 4-1), the ospf protocol operating structure body of LSA collector is carried out initialization, mainly comprise the registration of clock virtual thread of registration, the LSA refresh process of the initialization of initialization, the LSA database of initialization, the regional number of initialization, the network prefix of the network interface chained list that moves ospf protocol, clock virtual thread that MaxAge LSA handles;

Step 4-2), set up Netz ocket for the LSA collector and connect, and to the virtual thread control centre read wait for that chained list registration OSPF reads to wrap virtual thread;

Step 4-3), the interface or the region allocation order of reading configuration file, and whether the network interface of the LSA collector obtained in the step 3) met distribution principle according to its IP address be assigned in the OSPF respective regions;

Step 4-4), the network interface that is assigned with joins AllSPFRouters multicast group, and to the InterfaceUp incident of control centre's registration ospf interface state machine;

Step 5), all the operation ospf protocols network interface in choose the sign (ID) of the maximum of interface IP address as the LSA collector;

Step 6), virtual thread control centre are according to the scheduling strategy of the virtual thread of determining, scheduling is also carried out resulting virtual thread, set up syntople according to ospf protocol standard and the particular neighbor router revised through compatibility, the router of setting up syntople is called neighbor router, gathers LSA information in setting up the process of syntople; Comprise:

Step 6-1), the InterfaceUp incident of the ospf interface state machine of registration virtual thread control centre scheduled for executing step 4-4), the ospf interface state of the network interface of LSA collector is transformed into ISM_DROther or ISM_POINTOPOINT by ISM_Down, and begin periodically to send the Hello bag, include the ID of LSA collector in the Hello that the is sent bag;

Step 6-2), neighbor router Hello bag that the LSA collector is sent handles, and after finishing dealing with, sends the Hello bag of self, the ID of LSA collector will be contained as neighbours in the tabulation in the neighbor list territory in this Hello bag;

Step 6-3), the LSA collector receives and handles the Hello bag that neighbor router sends, wrap the IP source address of pairing IP bag according to this Hello, the LSA collector determines that this Hello bag is from new neighbor, a newly-built structure of describing neighbor state, information, and this neighbor state of initialization is NSM_Down;

Step 6-4), the LSA collector carries out the HelloReceived incident of ospf neighbor state machine, the neighbor state with the LSA collector is converted to NSM_Init then;

Step 6-5), the LSA collector continue to handle the Hello bag that neighbor router sends, and detects the ID of self in the neighbor list territory of this Hello bag, carries out the 2-WayReceived incident of ospf neighbor state machine;

Step 6-6), the neighbor state of LSA collector is converted to NSM_ExStart, and send the first ospf database that is used to consult Master/Slave and describe bag;

Step 6-7), neighbor router receives after first ospf database describes bag, contrast LSA collector and the ID of self determine that the big person of ID be role Master, beam back an ospf database description and wrap, and state the role of oneself;

Step 6-8), the LSA collector receives after this ospf database that neighbor router sends describes bag, clear and definite self-role, so far, the Master/Slave that syntople is set up in the process consults to finish, the big person of ID is Master, the little person of ID is Slave;

Step 6-9), the neighbor state of LSA collector is converted to NSM_Exchange, and bring into use ospf database to describe bag and carry out the exchange of LSA Link State descriptor, exchange process is controlled by Master, and the LSA collector can not transmit the descriptor of self Link State;

Step 6-10), after LSA Link State descriptor exchange finishes, the neighbor state of LSA collector will be converted to NSM_Loading, the neighbor state of neighbor router will be converted to the NSM_Full state;

Step 6-11), the LSA collector sends the OSPF request package to neighbor router;

Step 6-12), neighbor router sends corresponding OSPF update package to the LSA collector;

Step 6-13), the LSA collector is beamed back the respond packet of corresponding update package again, send all and receive that up to the OSPF of LSA collector request package OSPF update package that all are corresponding and respond packet send finishes, whole adjacency is set up process and is finished, and the neighbor state of LSA collector also is transformed into the NSM_Full state.

In the technique scheme, in described step 2) in, in described initialization operation process, the incident chained list that the virtual thread that needs override to obtain carrying out is added described virtual thread control centre, the virtual thread relevant with clock joins the clock chained list of described virtual thread control centre, the virtual thread that is ready to OSPF bag read-write is added the ready chained list of described virtual thread control centre, with the virtual thread that also is not ready for the read-write of OSPF bag add respectively described virtual thread control centre read wait for chained list and write the wait chained list.

In the technique scheme, in described step 2) in, the scheduling strategy of described virtual thread is:

Priority scheduling incident virtual thread, suboptimum scheduling clock virtual thread, the ready virtual thread of excellent once more scheduling becomes ready virtual thread after the virtual thread that read-write is blocked is ready.

The invention has the advantages that:

1, method of the present invention has solved the contradiction that LSA acquisition scheme in the past can not taken into account full adjacent and passive type;

2, method of the present invention has effectively reduced the cpu resource consumption and the link bandwidth consumption of unnecessary collector and neighbor router simultaneously.

Description of drawings

The flow chart that Fig. 1 realizes in one embodiment for LSA passive collection method under the OSPF full adjacent condition of the present invention;

Fig. 2 reads the flow chart of configuration file, registration respective virtual thread for the inventive method in one embodiment;

Fig. 3 is that the inventive method is set up syntople, gathered the flow chart of LSA information according to ospf protocol standard of revising through compatibility and particular neighbor router in one embodiment;

Fig. 4 is for LSA collector and neighbor router are set up the schematic diagram of syntople in one embodiment;

Fig. 5 is the interactive relation figure between LSA collector and neighbor router.

Embodiment

The present invention is further illustrated below in conjunction with the drawings and specific embodiments.

In the present embodiment, the realization of the inventive method is based on Redhat Linux 9.0 operating systems, and the network interface unit that is adopted is an ethernet network interface card, and configuration file format is as follows:

router?lsac

network?prefixarea?areaid

Wherein, prefix and areaid are command parameter, and prefix represents a network prefix, and areaid represents the ID in a zone.

Before method of the present invention is specifically described, also need LSA collector related in this method is described.Involved LSA collector has been realized a compatible subclass of ospf protocol among the present invention, and it comprises ospf interface state machine, ospf neighbor state machine and corresponding OSPF packet handing module.Wherein, the main ospf interface state of being responsible for LSA collector interface of ospf interface state machine part is transformed into other each Interface status from initial condition ISM_Down.The main process of being responsible for setting up between LSA collector and the general physical neighborhood router ospf neighbor relation of two-way communication of ospf neighbor state machine part, and needs are set up the process (following neighborhood, the syntople of abbreviating as respectively) of setting up the ospf adjacency relation between the physical neighborhood router of ospf adjacency relation, realize the collection to LSA in setting up the process of syntople.General, the ospf neighbor relation just is meant the physical neighborhood router, wraps by periodic Hello and safeguards and confirm two-way communication between physical neighborhood; The syntople of OSPF is that the neighborhood by OSPF further develops and comes, the foundation of the syntople of OSPF at first will be set up the neighborhood of OSPF, at point-to-point, point is in the network of multiple spot type, ospf router need continue to set up syntople with neighbor router, at NBMA, in the network of broadcast multipath access type, the router that Interface status is in ISM_DROther need be in ISM_DR with Interface status, the neighbor router of ISM_BDR is set up syntople, and the neighbor router that Interface status is in the router of ISM_BDR also to be needed to be in ISM_DR with Interface status is set up syntople.The OSPF packet handing module mainly is responsible for the processing of each ospf protocol bag, and carry out the management and running of ospf interface state machine or ospf neighbor state machine according to result, particularly in the process of handling the OSPF update package, the OSPF packet handing module of LSA collector will no longer comprise the process of flooding.The LSA collector is not realized functions such as the routing table of ospf protocol normalized definition is calculated, the virtual link support of LSA collector end, the support of Area Border Router characteristic.

Above-mentioned LSA collector can be realized the collection to network uplink state advertisement with after Ethernet is connected.As shown in Figure 4, the LSA collector links to each other with Ethernet, also is connected with a plurality of routers simultaneously on Ethernet, elects DR (Designated Router according to certain rule between these routers, Designated Router) and BDR (Backup Designated Router, BDR).Wherein, described rule be meant all greater than zero router interface priority in, select maximumly as DR, remove the DR that this has been selected then, select maximum again as BDR; When maximum priority has when a plurality of, more corresponding router id, maximum ID person obtains the triumph of current election.The ospf interface state that is elected as DR and BDR router is converted to ISM_DR and ISM_BDR respectively, and other ospf interface state exchanges that are not elected as the router of DR or BDR are ISM_DROther.Ospf protocol regulation: the ospf interface state exchange be ISM_DROther router must and DR and BDR between set up syntople.The foundation of syntople all belongs to prior art between the election of Designated Router and BDR and router, no longer elaborates in the present embodiment.

On the basis of the above description, LSA passive collection method under the OSPF full adjacent condition of the present invention is elaborated.As shown in Figure 1, the specific implementation step of the inventive method is as follows:

Step 10, system's execution environment of LSA collector is done initialization; In this step, described initialization operation mainly comprises and the file directory permission mask is initialized as 0027, the initialization of common signal and correlation function thereof.For example, hang-up signal SIGHUP, interrupt signal SIGINT, termination signal SIGTERM etc.

Step 20, the virtual thread control centre in the LSA collector is made initialization operation, in initialization procedure, needs are preferentially obtained the incident chained list that the virtual thread carried out adds the virtual thread control centre, the virtual thread relevant with clock joins the clock chained list of virtual thread control centre, the virtual thread that is ready to the read-write of OSPF bag is entered ready chained list, the virtual thread that also is not ready for the read-write of OSPF bag is entered respectively read to wait for chained list and write the wait chained list.

Above-mentioned virtual thread control centre at the scheduling strategy in when work is: searched events chained list at first, the incident chained list is retrieved the clock of clock chained list when finding when empty again, when not finding, retrieve ready chained list again, if ready chained list is empty, then call select () system function, with the time difference of current time and clock time on the horizon as blocking time (if current do not have a clock-type virtual thread, permanent blockage then, arrival up to the OSPF bag) is blocked on the Netz ocket, waits for the arrival of OSPF bag.After OSPF bag arrives, the LSA collector will no longer block, and OSPF be read to wrap virtual thread shift out and read to wait for chained list and join ready chained list, dispatch the virtual thread that obtains in this ready chained list once more, and scheduled for executing.If when not having the arrival of OSPF bag through blocking time, will there be overtime clock in system this moment, and system no longer is blocked on this Netz ocket this moment, and system is with the pairing virtual thread of this timeout clock of scheduled for executing.As long as more than retrieve an executable virtual thread in the chained list, then carry out the pairing function of this virtual thread and enter scheduling next time.

Step 30, utilize Linux netlink socket to obtain Ethernet interface information on the LSA collector;

Step 40, read configuration file, and register corresponding virtual thread to the virtual thread control centre.Existing relevant explanation in the configuration file that the is read description in front is further described this step below in conjunction with Fig. 2:

Step 41, the router lsac that at first reads in the configuration file order, the effect of this order is that the ospf protocol operating structure body to the LSA collector carries out initialization, and described ospf protocol operating structure body mainly comprises the registration of clock virtual thread of registration, the LSA refresh process of the initialization of initialization, the LSA database of initialization, the regional number of initialization, the network prefix of the Ethernet interface chained list that moves ospf protocol, clock virtual thread that MaxAge LSA handles.

Step 42, set up Netz ocket for the LSA collector and connect, and to the virtual thread control centre read wait for that chained list registration OSPF reads to wrap function, thereby be the preparation of carrying out the first step of reading of OSPF packet;

Step 43, the network prefix area areaid order of reading configuration file, and the principle whether Ethernet interface of the LSA collector that will obtain before mates prefix according to its IP address is assigned in the represented OSPF respective regions of areaid;

Step 44, the Ethernet interface that is assigned with join AllSPFRouters multicast group, carry out the preparation that the OSPF bag reads fully, and register the InterfaceUp incident of ospf interface state machine to the control centre.

Step 50, all the operation ospf protocols Ethernet interface in choose the ID of the maximum of interface IP address as the LSA collector.

Resulting virtual thread is dispatched and carried out in step 60, virtual thread control centre according to pre-determined scheduling strategy, set up syntople according to the ospf protocol standard and the DR that revise through compatibility, collect LSA information in the process setting up of syntople.As shown in Figure 3, the specific implementation process of this step is as follows:

The InterfaceUp incident of the ospf interface state machine of registration in step 61, the virtual thread control centre scheduled for executing step 44, the ospf interface state of the ether interface of LSA collector is transformed into ISM_DROther by ISM_Down, and begin periodically to send the Hello bag, include the ID of LSA collector in the Hello that the is sent bag.

Step 62, DR handle the Hello bag that the LSA collector sends, and after handling, send the Hello bag of self, and the ID of LSA collector will be contained as neighbours in the tabulation in the neighbor list territory in this Hello bag.

Step 63, LSA collector receive and handle the Hello bag that DR sends, because the Hello of OSPF bag is encapsulated in the IP bag, therefore wrap the IP source address of pairing IP bag according to this Hello, the LSA collector can determine that this Hello bag is from new neighbor, therefore a newly-built structure of describing neighbor state, information, and this neighbor state of initialization is NSM_Down;

Step 64, LSA collector are carried out the HelloReceived incident of ospf neighbor state machine, and the neighbor state with the LSA collector is converted to NSM_Init then;

Step 65, LSA collector continue to handle the Hello bag that DR sends, and detect the ID of self in the neighbor list territory of this Hello bag, therefore carry out the 2-WayReceived incident of ospf neighbor state machine.

Step 66, owing to need to form syntople between LSA collector and DR, so the neighbor state of LSA collector will be converted to NSM_ExStart, and send the first ospf database that is used to consult Master/Slave and describe bag;

After step 67, DR received first ospf database description bag, contrast LSA collector and the ID of self determined the big person of ID for behind the role Master, beamed back an ospf database description and wrapped, and stated the role of oneself;

Step 68, LSA collector receive after ospf database that this DR sends describes bag, and self-role also will be clear and definite, and since then, the Master/Slave that syntople is set up in the process consults to finish, and the big person of ID is Master, and the little person of ID is Slave;

The neighbor state of step 69, LSA collector is converted to NSM_Exchange, and bring into use ospf database to describe bag and carry out the exchange of LSA Link State descriptor, exchange process is controlled by Master, and the LSA collector will can not transmit the descriptor of self Link State;

In this step, because the LSA collector can not transmit the descriptor of self Link State, therefore DR will can not ask this link-state information, in its LSA database, can there be this link-state information yet, thereby will only has a one way link between LSA collector and the DR from DR to the LSA collector.

After step 610, the exchange of LSA Link State descriptor are finished, the neighbor state of LSA collector will be converted to NSM_Loading, and the neighbor state of DR will be converted to the NSM_Full state.

In follow-up step, set up the OSPF update package transfer phase of syntople, the LSA collector can not received the request to self link-state information, just can not send the OSPF update package that contains self link-state information yet; The LSA collector had not both sent the Link State descriptor of self like this, did not send this link-state information yet, thereby made the neighbor state of DR can enter into this stable state of NSM_Full;

Step 611, LSA collector send the OSPF request package to DR;

Step 612, DR send corresponding OSPF update package to the LSA collector;

Step 613, LSA collector are beamed back the respond packet of corresponding update package again, send all and receive that up to the OSPF of LSA collector request package OSPF update package that all are corresponding and respond packet send finishes, whole adjacency is set up process and is finished, and the neighbor state of LSA collector also is transformed into the NSM_Full state.

By the description of above-mentioned step 610 and step 613 as can be known, forming both sides' neighbor state between LSA collector and DR all is the full adjacency of NSM_Full, and because the link-state information of LSA collector is not present in the LSA database of DR, therefore only there is a one way link of describing by DR between LSA collector and the DR from DR to the LSA collector, and one way link is not to be used in topology in the ospf protocol standard, route is calculated, therefore prevented that effectively the LSA collector is to network topology, the influence of route and data forwarding has realized the OSPF full adjacent, the acquisition mode of passive type.

Claims

1, LSA passive collection method under a kind of OSPF full adjacent condition may further comprise the steps:

Step 3), obtain the network interface information on the LSA collector;

The InterfaceUp incident of the ospf interface state machine of being registered virtual thread control centre scheduled for executing step 4-4 step 6-1)), the ospf interface state of the network interface of LSA collector is transformed into ISM_DROther or ISM_POINTOPOINT by ISM_Down, and begin periodically to send the Hello bag, include the ID of LSA collector in the Hello that the is sent bag;

2, LSA passive collection method under the OSPF full adjacent condition according to claim 1, it is characterized in that, in described step 2) in, in described initialization operation process, the incident chained list that the virtual thread that needs override to obtain carrying out is added described virtual thread control centre, the virtual thread relevant with clock joins the clock chained list of described virtual thread control centre, the virtual thread that is ready to OSPF bag read-write is added the ready chained list of described virtual thread control centre, with the virtual thread that also is not ready for the read-write of OSPF bag add respectively described virtual thread control centre read wait for chained list and write the wait chained list.

3, LSA passive collection method under the OSPF full adjacent condition according to claim 1 is characterized in that, in described step 2) in, the scheduling strategy of described virtual thread is: