鏈路狀態(tài)路由協(xié)議ppt課件

1、 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-1Introducing Link-State and Balanced Hybrid RoutingMedium-Sized Routed Network Construction 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-2Outline Overview How Routing Information is Maintained with Link State Link-State Routing Pr

2、otocol Algorithms Benefits and Limitations of Link-State Routing When to Use Link-State Routing Protocols Balanced Hybrid Routing Summary 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-3Link-State Routing ProtocolsAfter an initial flood of LSAs, link-state routers pass small, event-trigger

3、ed link-state updates to all other routers. 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-4LS與與DV對比的優(yōu)勢對比的優(yōu)勢:n拓?fù)浒l(fā)生變化時(shí)拓?fù)浒l(fā)生變化時(shí),收斂快收斂快.n發(fā)送定期更新的頻率低發(fā)送定期更新的頻率低.n網(wǎng)絡(luò)可以以層次方式劃分區(qū)域網(wǎng)絡(luò)可以以層次方式劃分區(qū)域,減少路由變卦范圍減少路由變卦范圍.n (OSPF,ISIS)n支持無類編址支持無類編址.n支持路由匯總支持路由匯總. 2007 Cisco Systems, Inc. All rights reserved.ICND

4、2 v1.02-5OSPF Hierarchical Routing autonomous systems由骨干區(qū)域area0和普通區(qū)域組成 區(qū)域化的網(wǎng)絡(luò)減少路由更新的流量泛洪.Stub末梢區(qū)域末梢區(qū)域Totally Stub絕對末梢區(qū)域絕對末梢區(qū)域NSSA次末梢區(qū)域次末梢區(qū)域Totally NSSA絕對次末梢區(qū)域絕對次末梢區(qū)域 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-6Link-State Routing Protocol Algorithms 2007 Cisco Systems, Inc. All rights r

5、eserved.ICND2 v1.02-7Distance Vector and Link-State Protocols Comparison對整個(gè)網(wǎng)絡(luò)拓?fù)涞牧私鈱φ麄€(gè)網(wǎng)絡(luò)拓?fù)涞牧私庥?jì)算路由的算法計(jì)算路由的算法1間隔矢量：能使路由器知道一個(gè)間隔矢量：能使路由器知道一個(gè)IP網(wǎng)絡(luò)在網(wǎng)絡(luò)里的哪個(gè)方向網(wǎng)絡(luò)在網(wǎng)絡(luò)里的哪個(gè)方向,并并要經(jīng)要經(jīng) 過多少跳；過多少跳； 2鏈路形狀：路由是從拓?fù)浔砝镉?jì)算出來鏈路形狀：路由是從拓?fù)浔砝镉?jì)算出來路由更新路由更新Rip v1 廣播更新廣播更新,周期性更新周期性更新,發(fā)整張路由表發(fā)整張路由表OSPF eigrp 增量更新增量更新,組播更新組播更新,觸發(fā)更新觸發(fā)更新 20

6、07 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-8Benefits of Link-State Routing 鏈形狀協(xié)議根據(jù)本錢cost)來選擇最優(yōu)途徑 經(jīng)過運(yùn)用觸發(fā)更新，鏈路形狀協(xié)議可以將網(wǎng)絡(luò)拓?fù)渥兓⒖贪l(fā)送給網(wǎng)絡(luò)中受影響的一切路由器，從而縮短了收斂時(shí)間 由于每臺(tái)路由器都有完好的網(wǎng)絡(luò)描畫信息，因此不容易構(gòu)成路由選擇環(huán)路 經(jīng)過細(xì)心地設(shè)計(jì)網(wǎng)絡(luò)，可最大限制地減少鏈路形狀數(shù)據(jù)庫的規(guī)模，從而減少SPF計(jì)算量，提高會(huì)聚速度 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-9Drawbacks of Link-State Routing 鏈路形狀協(xié)議有路由選擇表、拓?fù)浔砗袜従颖?，假設(shè)在大型的網(wǎng)絡(luò)中，能夠需求占用大量的內(nèi)存 SPF在計(jì)算最正確途徑時(shí)需求占用CPU周期，假設(shè)網(wǎng)絡(luò)較大或復(fù)雜，需求占用大量的CPU資源 為了防止占用過多的內(nèi)存和CPU資源，必需采用嚴(yán)厲的層次型設(shè)計(jì)方案 啟動(dòng)時(shí)需求一定的時(shí)間才干轉(zhuǎn)發(fā)數(shù)據(jù)包。鄰接 2007 Cisco Systems, Inc. All rights reserved.ICND2 v1.02-10Balanced Hybrid Routing-EIGRP Shares attribut