CN101651617B

CN101651617B - Method for selecting stable route from Internet route

Info

Publication number: CN101651617B
Application number: CN2009100932096A
Authority: CN
Inventors: 徐明伟; 李琦; 杜德慧; 江学智
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2009-09-15
Filing date: 2009-09-15
Publication date: 2012-01-04
Anticipated expiration: 2029-09-15
Also published as: CN101651617A

Abstract

The invention provides a method for selecting a stable route from Internet routes, comprising the following steps: receiving a neighbor notifying route, and judging whether the notifying route is caused by a fault or not and whether the current route is required to be cancelled or changed; if the notifying route is judged to be caused by the fault and the current route is required to be cancelled or changed, starting a stable inter-domain route protocol sBGP to reselect a route; and selecting the most stable selectable route as the current route according to the sBGP. In the invention, after a router receives a route notice triggered by the fault, a heuristic route selection algorithm is adopted to select the current most stable selectable route as the best route; through stable route selection, the router can select an effective stable route so as to avoid the invalid route search and router processing spending caused by continuous updating of the route.

Description

Interconnection path by in stable route selection method

Technical field

The present invention relates to Internet technical field, especially relate to interconnection path by in stable route selection method, solve Border Gateway Protocol (Border Gateway Protocol, convergence BGP) and stability problem.

Background technology

In the Internet, network failure is frequent, and existing inter-domain routing protocol (Border GatewayProtocol BGP) can not adapt to the solution of network failure well.In the prior art, inter-domain routing protocol will experience long invalid route search process, and this has caused in the Internet, taking place lot of data bag packet loss phenomenon.

In order to alleviate or to solve BGP route slow convergence problem, prior art has also proposed a lot of improved BGP schemes.But these schemes are because the shortcoming of design itself can not improve the performance of BGP effectively.For example, the root information that RCN and EPIC change through increase route in the BGP notice message is accelerated the convergence of route, but their improvement performance depends on topology of networks to a great extent, and these schemes are not supported incremental deploying; The CA scheme is accelerated routing convergence through the invalid route that detects in the advertising of route, but this scheme has increased very big computational load to router; Ghost Flushing scheme is accelerated routing convergence through before the new route of announcement, cancelling old route; But can't avoid the invalid search procedure of route; In addition, Ghost Flushing has also increased a lot of BGP notice messages, and the constringency performance of this scheme can worsen failover the time.

In addition, along with the development of Internet technology, the growth of new internet, applications and Internet user's quantity is all had higher requirement to the convergence rate and the communication load ability of Internet, and this has further increased the load problem of existing BGP.

Summary of the invention

The objective of the invention is one of to address the aforementioned drawbacks, the route that the propagation time is long and routing policy causes of long, route of the route searching time that particularly solves BGP is convergence problem not, thereby effectively improves the performance of BGP.

For addressing the above problem; One aspect of the present invention propose a kind of interconnection path by in stable route selection method; May further comprise the steps: accept the route of neighbor advertisement, and the route of judging said announcement whether since fault cause and whether need cancel or change current route; If the route of judging said announcement is owing to fault causes, and need cancel or change current route, then stable inter-domain routing selection algorithm sBGP reselects route; Select the most stable selectable route as current route according to said sBGP.

As one embodiment of the present of invention, select the most stable selectable route to comprise as current route according to said sBGP: whether the AS path of judging current selected best route includes the fault message AS in the routing update; If include the fault message AS in the routing update, then in input routing information base Adj-RIB-IN, select the longest route of life period; Whether the life period of judging the route that said life period is the longest is greater than threshold value; If the life period of the route that said life period is the longest whether greater than threshold value, then further judges whether the longest route of said life period comprises faulty link; If do not comprise faulty link, then that said life period is the longest route is as current route.

As one embodiment of the present of invention, also comprise: if the life period of the longest route of said life period less than threshold value, the route of then from said Adj-RIB-IN, selecting announcement recently is as current route.

As one embodiment of the present of invention, also comprise:, then in said Adj-RIB-IN, delete the longest route of said life period, and reselect the most stable route if the longest route of said life period comprises faulty link.

As one embodiment of the present of invention, include the attribute that the sign route changes event source in the said advertising of route.

As one embodiment of the present of invention, every time that route learning arrives of sign in said Adj-RIB-IN.

As one embodiment of the present of invention, also comprise: judge to stablize whether route changes in the Route Selection timer expired time; Route does not change in the Route Selection timer expired time if stablize, and then selects traditional route selection algorithm to select route.

As one embodiment of the present of invention, also comprise: variation has taken place in route in the Route Selection timer expired time if stablize, and then restarts said stable Route Selection timer.

The present invention proposes a stable inter-domain routing selection algorithm sBGP (Stable BGP); In sBGP of the present invention; After router is received the advertising of route by fault triggering, then adopt didactic route selection algorithm to select present most stable selectable route as best route.Through stablizing Route Selection, router can select effectively to stablize route, brings in constant renewal in the router processing expenditure of introducing to avoid invalid route search and route.Show that through analysis and simulated experiment sBGP not only can effectively improve the performance of the convergence of BGP, and can reduce the communication-cost in the convergence process.

Aspect that the present invention adds and advantage part in the following description provide, and part will become obviously from the following description, or recognize through practice of the present invention.

Description of drawings

Above-mentioned and/or additional aspect of the present invention and advantage are from obviously with easily understanding becoming the description of embodiment below in conjunction with accompanying drawing, wherein:

Fig. 1 be the embodiment of the invention interconnection path by in the decision process sketch map of stable Route Selection;

Fig. 2 is the sBGP route selection algorithm of the embodiment of the invention;

Fig. 3 be the embodiment of the invention interconnection path by in stable route selection method flow chart.

Embodiment

Describe embodiments of the invention below in detail, the example of said embodiment is shown in the drawings, and wherein identical from start to finish or similar label is represented identical or similar elements or the element with identical or similar functions.Be exemplary through the embodiment that is described with reference to the drawings below, only be used to explain the present invention, and can not be interpreted as limitation of the present invention.

Stable BGP route selection algorithm (Stable BGP (the sBGP)) target that the present invention proposes is the localization process Route Selection; Route is changed among a small circle to be taken place; Through selecting to stablize route, greatly reduced the route change frequency, the stability of route is provided.And sBGP selects stable route to guarantee to eliminate route search process invalid in the routing convergence process, has solved route long problem computing time.In addition; Because route re-computation is only carried out in selected route receives the router of fault effects; So routing failure information will be propagated in limited node; Solved the problem of route propagation time course, simultaneously owing in Adj-RIB-IN, there not being two routes, so sBGP has also solved the later not convergence problem of routing failure with same stable property.The present invention is in order to realize stablizing Route Selection, and sBGP has increased an event source that attribute changes with the sign route in the standard bgp route advertisement, and in the Adj-RIB-IN of BGP (input routing information base), identifies every time that route learning arrives.In router is received advertising of route message, have fault message, then router will be launched the stable route selection algorithm of sBGP.The present invention has also increased by two extra Route Selection in the sBGP decision process, promptly select present available route and select the longest route running time.At first to select stablize first step of route be preferentially to select present available route to have avoided unnecessary route re-computation process to router.If current selected route is influenced by faulty link, then sBGP will in Adj-RIB-IN, select running time the longest route the most oneself best route and announcement give neighbours, stablize routing procedure thereby accomplish.

As shown in Figure 1, for the interconnection path of the embodiment of the invention by in the decision process sketch map of stable Route Selection.At first; The present invention is preferential select at present available route as current route (step 1), in embodiments of the present invention, the source of trouble that sBGP can change through the identification route; Avoided router to receive cancelling the route of seek invalid after the message, so avoided the very long route search time.And the sBGP router only just can carry out the decision-making again of route when current route is invalid, so the most stable in the each statement of the sBGP router always current route of route of coming out, and has effectively avoided stating repeatedly of route and the route that causes suppresses.Similarly,, and only select own most stable selectable route in the decision process because the sBGP router only carries out route and make a strategic decision again when current route is unavailable, so the sBGP route that can not occur causing owing to routing policy problem convergence problem not.In addition, in sBGP routing decision step 2, if the route of minimum operation less than τ, then adopts the route of new statement.The present invention stablizes the judgement of Route Selection through τ.Specific algorithm is as shown in Figure 3, and the present invention at first selects the longest route of router uptime, and has surpassed τ the effective time of this route.If all surpass τ at present the effective time of all routes, the route of the new statement of then selecting to receive, at this time selected route also is stable route.Because sBGP has following theorem: in sBGP, because the available route of the maximum duration that the route of new statement is a neighbor router to be adopted, also be a kind of selection strategy of stable route so when local no available stable route, select newly to declare route; This principle also is the selection strategy of the stable route of BGP.Wherein, step 1 among Fig. 1 and step 2 are respectively to realize that sBGP stablizes the core of Route Selection, have solved the problem of present BGP route, and other steps in this Fig. 1 are described no longer one by one.Specifically, carry out the decision-making of Route Selection through these two steps in the routing decision process through the source of trouble and all unsettled routes that the identification route changes.

As shown in Figure 3, for the interconnection path of the embodiment of the invention by in stable route selection method flow chart, may further comprise the steps:

Step S301 accepts the route of neighbor advertisement, and the route of judging said announcement whether since fault cause and whether need cancel or change current route.If the route of judging announcement is owing to fault causes, and need cancel or change current route r ^*, then start sBGP and reselect route.For example, if receive a routing update that has failure identification, then BGP launches and stablizes route selection algorithm and reselect route.

Step S302 judges current route r ^*Whether comprise faulty link, judge in one embodiment of the invention promptly whether the AS path of current selected best route includes the fault message AS in the routing update.If current route r ^*Do not comprise faulty link, then need not to reselect route.

If step S303 is current route r ^*Comprise faulty link,, then in Adj-RIB-IN (input routing information base), select the longest route r of life period if promptly the AS path of current selected best route includes the fault message AS in the routing update.

Step S304, whether the life period of judging the route r that life period is the longest is greater than threshold tau.

Step S305 is if whether the life period of the longest route r of life period then further judges whether life period the longest route r comprise faulty link greater than threshold tau.

Step S306, if the longest route r of life period does not comprise faulty link, then that life period is the longest route r is as current route.

Step S307, if the life period of the longest route r of life period less than threshold tau, the route of then from Adj-RIB-IN, selecting announcement recently is as current route.

Step S308 if the longest route r of life period comprises faulty link, then deletes the longest route r of life period, and reselects the most stable route in Adj-RIB-IN.

Because sBGP proposed by the invention is selected to be to stablize route, so sBGP has reduced the stability that the route change frequency provides route greatly.And sBGP selects stable route to guarantee to eliminate route search process invalid in the routing convergence process, has solved route long problem computing time; Because route re-computation is only carried out in selected route receives the router of fault effects, so routing failure information will be propagated in limited node, has solved the problem of route propagation time course; Owing in Adj-RIB-IN, do not have two routes, so sBGP has solved the later not convergence problem of routing failure with same stable property.

In addition, sBGP may select to be provided with among some ISP (Internet Service Provider, ISP) route of low priority.The angle of the situation that collateral security overall situation route is stable, a part of interests of loss ISP are good trading off, and after fault takes place, route occurs especially and do not restrain.In sBGP, the present invention has also realized recovering normal Route Selection.In sBGP, the present invention has realized stable Route Selection timer, has promptly in a single day launched stable Route Selection when each route, will launch a timer among the sBGP.Have only when route timer expired in the time route do not change, then behind timer expired, router will reactivate traditional route selection algorithm.But variation has taken place in route in the timer expired process, and then timer is with reclocking.Because the Route Selection behind the timer expired does not have very long routing convergence process, and the route reselection of sBGP select occur over just among a small circle in, so the convergence time of route is very short.

Route proposed by the invention is stablized selection scheme (sBGP) and is improved the BGP routing convergence.The validity of detection algorithm route at first. have only when present selected route to receive fault effects, sBGP just can reselect route.Be different from existing BGP, sBGP selects the optimal selection the most of most stable selectable route, can shorten the BGP routing convergence time so greatly and effectively reduce the BGP routing update message quantity in the convergence process.This shows that the present invention can reach its intended purposes.

Any mentioning " embodiment ", " embodiment ", " illustrative examples " etc. mean the concrete member, structure or the characteristics that combine this embodiment to describe and are contained among at least one embodiment of the present invention.Not necessarily refer to identical embodiment in this schematic statement everywhere of this specification.And when combining any embodiment to describe concrete member, structure or characteristics, what advocated is, realizes that in conjunction with other embodiment such member, structure or characteristics all drop within those skilled in the art's the scope.

Although carried out detailed description with reference to a plurality of illustrative examples specific embodiments of the invention of the present invention; But it must be understood that; Those skilled in the art can design multiple other improvement and embodiment, and these improve and embodiment will drop within the spirit and scope.Particularly, within the scope of aforementioned open, accompanying drawing and claim, can make rational modification and improvement aspect the layout of parts and/or subordinate composite configuration, and can not break away from spirit of the present invention.Except the modification and the improvement of parts and/or layout aspect, its scope is limited accompanying claims and equivalent thereof.

Claims

An interconnection path by in stable route selection method, it is characterized in that, may further comprise the steps:

Accept the routing update of neighbor advertisement, and the routing update of judging said announcement whether since fault cause and whether need cancel or change current route; Wherein include the attribute that the sign route changes event source in the announcement;

If the routing update of judging said announcement is owing to fault causes, and need cancel or change current route, then start stable inter-domain routing protocol sBGP and reselect route;

Select the most stable selectable route as current route according to said sBGP;

Select the most stable selectable route to comprise according to said sBGP as current route:

Whether the AS path of judging current selected best route includes the fault message AS in the routing update;

If include the fault message AS in the routing update, then in input routing information base Adj-RIB-IN, select the longest route of life period, wherein every time that route learning arrives of sign in said Adj-RIB-IN;

Whether the life period of judging the route that said life period is the longest is greater than threshold value;

If the life period of the route that said life period is the longest greater than threshold value, then further judges whether the longest route of said life period comprises faulty link;

If do not comprise faulty link, then that said life period is the longest route is as current route;

If the life period of the route that said life period is the longest is less than threshold value, the route of then from said Adj-RIB-IN, selecting announcement recently is as current route.
2. interconnection path as claimed in claim 1 by in stable route selection method, it is characterized in that, also comprise:

If the longest route of said life period comprises faulty link, then in said Adj-RIB-IN, delete the longest route of said life period, and reselect the most stable route.
3. interconnection path as claimed in claim 1 by in stable route selection method, it is characterized in that, when in a single day each route has launched stable Route Selection, will launch a timer among the sBGP;

Judge to stablize whether route changes in the Route Selection timer expired time;

Route does not change in the Route Selection timer expired time if stablize, and then behind timer expired, router will reactivate traditional route selection algorithm and select route.
4. interconnection path as claimed in claim 3 by in stable route selection method, it is characterized in that, also comprise:

Variation has taken place in route in the Route Selection timer expired time if stablize, and then restarts said stable Route Selection timer.