第五章ip路由.ppt

1、第五章 IP 路由,本章內容,PLANNING & DESIGNING Design a simple LAN using Cisco Technology Design an IP addressing scheme to meet design requirements Select an appropriate routing protocol based on user requirements Design a simple internetwork using Cisco technology IMPLEMENTATION & OPERATION Configure routing

2、 protocols given user requirements Configure IP addresses, subnet masks, and gateway addresses on routers and hosts Configure a router for additional administrative functionality Perform an initial configuration on a router Perform an initial configuration on a switch,TROUBLESHOOTING Perform LAN and

3、 VLAN troubleshooting Troubleshoot routing protocols Troubleshoot IP addressing and host configuration Troubleshoot a device as part of a working network TECHNOLOGY Evaluate the characteristics of routing protocols Evaluate TCP/IP communication process and its associated protocols,什么是IP路由,difference

4、 between a routing protocol and a routed protocol,A routing protocol Dynamically find all the networks in the internetwork Ensure that all routers have the same routing table Determines the path of a packet through an internetwork Select a best path to delivery Examples of routing protocols are RIP,

5、 IGRP, EIGRP, and OSPF,A routed protocol Be used to send user data(packets) through the established enterprise Assigned to an interface Determine the method of packet delivery Examples of routed protocols are IP and IPX,學習本章目標：配置和校驗思科路由器,靜態(tài)路由 IP ROUTE NETWORK MASK NEXT-HOP 缺省路由 IP ROUTE 0.0.0.0 0.0.

6、0.0 DEFAULT-GATEWAY 動態(tài)路由 ROUTER RIP ROUTER IGRP,路由基礎,Routers route traffic to all the networks in your internetwork Configure logical network addresses, such as IP addresses Routers dont really care about hosts address Care about networks and the best path to each network The logical network address

7、 of the destination host is used to get packets to a network through a routed network The hardware address of the host is used to deliver the packet from a router to the correct destination host,路由器路由數據包的基本條件,目的地地址 任何一個能夠學習遠端網絡的鄰居路由器 到所有遠端網絡的可能路由器 到每一個遠端網絡的最優(yōu)路由 如何維護和校驗路由信息,路由器 A要想知道路由器C的存在，有兩種辦法： 一是

8、，通過鄰居路由器B來得知路由器C的存在。 二是，通過管理員手工添加路由來得知路由器C的存在。,路由器如何獲得遠端路由的信息,路由表,router# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF ext

9、ernal type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is 218.12.46.137 to network 0.0.0.0 218.12.46.0/29 is subnet

10、ted, 1 subnets C 218.12.46.136 is directly connected, FastEthernet0/0 C 192.168.3.0/24 is directly connected, FastEthernet0/1 S* 0.0.0.0/0 1/0 via 218.12.46.137,The router then builds a routing table that describes how to find the remote networks.,直連的網絡，路由器知道如何到達目的網絡,非直連網絡，路由器到達遠端網絡有兩種方式： 網管員手工添加靜態(tài)路

11、由 動態(tài)路由,單路由與多路由網絡,單個路由器的IP路由過程,多路由器的IP路由一,多路由器的IP路由二,多路由器的IP路由三,多路由器的IP路由四查看路由表,多路由器的IP路由五Lab_B配置,多路由器的IP路由六- Lab_B路由表,Lab_B#sh ip route output cut Gateway of last resort is not set C 192.168.20.0/24 is directly connected, Serial0/0 C 192.168.40.0/24 is directly connected, Serial0/1 C 192.168.30.0 is

12、 directly connected FastEthernet 0/0 Lab_B#,多路由器的IP路由七 Lab_C配置,Lab_C(config)#interface fa0/0 Lab_C(config-if)#ip address 192.168.50.1 255.255.255.0 Lab_C(config-if)#description Lab_C LAN Connection Lab_C(config-if)#no shut Lab_C(config-if)#interface serial 0/0 Lab_C(config-if)#ip address 192.168.40.

13、2 255.255.255.0 Lab_C(config-if)#description WAN Connection to Lab_B Lab_C(config-if)#no shut Lab_C(config-if)#exit,多路由器的IP路由七 Lab_C路由表,Lab_C#sh ip route output cut Gateway of last resort is not set C 192.168.50.0/24 is directly connected, FastEthernet0/0 C 192.168.40.0/24 is directly connected, Ser

14、ial0/0 Lab_C#,思考,經過這樣的配置后，數據包是否可以經過多個路由器進行傳送到目標主機呢？ 答案是：否！ 為什么呢？,配置IP路由,Static routing Default routing Dynamic routing,配置IP路由-靜態(tài)路由,Static routing has the following benefits: There is no overhead on the router CPU, which means you could possibly buy a cheaper router than if you were using dynamic rou

15、ting. There is no bandwidth usage between routers, which means you could possibly save money on WAN links. It adds security, because the administrator can choose to allow routing access to certain networks only.,配置IP路由-靜態(tài)路由,Static routing has the following disadvantages: The administrator must reall

16、y understand the internetwork and how each router is connected in order to configure routes correctly. If a network is added to the internetwork, the administrator has to add a route to it on all routersby hand. Its not feasible in large networks because maintaining it would be a full-time job in it

17、self.,ip route destination_network mask next-hop_address or exitinterface administrative_distance permanent This list describes each command in the string: ip route The command used to create the static route. destination_network The network youre placing in the routing table. mask The subnet mask b

18、eing used on the network. next-hop_address The address of the next-hop router that will receive the packet and forward,靜態(tài)路由的配置格式,exitinterface You can use it in place of the next-hop address if you want, but its got to be on a point-to-point link, such as a WAN. This command wont work on a LAN such

19、as Ethernet. administrative_distance By default, static routes have an administrative distance of 1(or even 0 is you use an exit interface instead of a next hop address). You can change the default value by adding an administrative weight at the end of the command. Ill talk a lot more about this sub

20、ject later in the chapter when we get to the section on dynamic routing. permanent If the interface is shut down, or the router cant communicate to the next-hop router, the route will automatically be discarded from the routing table. Choosing the permanent option keeps the entry in the routing tabl

21、e no matter what happens.,靜態(tài)路由的配置格式續(xù),注：如果改變了靜態(tài)路由的管理距離，則此條路由被稱為浮動靜態(tài)路由。,靜態(tài)路由實戰(zhàn)配置,靜態(tài)路由實戰(zhàn)配置續(xù)一LAB_a配置,注意：直接鏈接到路由器端口網絡將自動添加到路由器的路由表中。 任何一個路由器的路由表中必須包含到達遠端網絡的路徑。,路由器A的路由表中除了包含直聯網段，還需要描述如何到達以下網段： 192.168.30.0 192.168.40.0 192.168.50.0,靜態(tài)路由實戰(zhàn)配置續(xù)一LAB_a配置,返回特權模式，輸入show running-config檢測路由器的配置。,靜態(tài)路由實戰(zhàn)配置續(xù)一LAB_a配置

22、,靜態(tài)路由實戰(zhàn)配置續(xù)一LAB_b配置,路由器B的路由表中除了包含直聯網段： 192.168.20.0 192.168.30.0 192.168.40.0 還需要描述如何到達以下網段： 192.168.10.0 192.168.50.0,靜態(tài)路由實戰(zhàn)配置續(xù)一LAB_b配置,返回特權模式，輸入show running-config檢測路由器的配置。,靜態(tài)路由實戰(zhàn)配置續(xù)一LAB_b配置,路由器C的路由表中除了包含直聯網段： 192.168.40.0 192.168.50.0 還需要描述如何到達以下網段： 192.168.10.0 192.168.20.0 192.168.30.0,靜態(tài)路由實戰(zhàn)配置續(xù)

23、一LAB_c配置,靜態(tài)路由實戰(zhàn)配置續(xù)一LAB_c配置,在路由器的全局配置模式下輸入以下命令：,返回特權模式，輸入show running-config檢測路由器的配置。,靜態(tài)路由實戰(zhàn)配置續(xù)一LAB_c配置,校驗路由器的配置,Lab_A#ping 192.168.50.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 172.16.50.1, timeout is 2 seconds: ! Success rate is 80 percent (4/5), round-trip min/avg/max = 64/

24、66/68 ms Lab_C#ping 192.168.10.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 172.16.10.1, timeout is 2 seconds: ! Success rate is 100 percent (5/5), round-trip min/avg/max = 64/67/72 ms,默認路由,Router(config)ip route 0.0.0.0 0.0.0.0 next-hop add | exit-interface Exit-interface 只能用在

25、stub-interface的網絡鏈接中。 有效減小路由表的長度。 減少系統(tǒng)開銷。 如果路由表沒有到遠端網絡的表項，則數據包將通過默認路由發(fā)送到遠端網絡。 非常適合企業(yè)到ISP的接入路由。,默認路由實列,以上是Labc的靜態(tài)路由配置，我們可以用一條默認路由來代替：,172.16.2.1,SO,靜態(tài)路由,172.16.1.0,B,172.16.2.2,Network,A,在小型網絡中適宜設置靜態(tài)路由。 靜態(tài)路由是雙向的，必須在兩個方向上配置才可使用。,B,Stub Network,指定一條可以到達目標網絡的路徑,Router(config)#ip route network mask addre

26、ss | interfacedistance permanent,靜態(tài)路由的配置,Stub Network,ip route 172.16.1.0 255.255.255.0 172.16.2.1,172.16.2.1,SO,靜態(tài)路由的例子,172.16.1.0,B,172.16.2.2,Network,A,B,這是一條單方向的路徑，必須配置一條相反的路徑。,Stub Network,ip route 0.0.0.0 0.0.0.0 172.16.2.2,缺省路由,172.16.2.1,SO,172.16.1.0,B,172.16.2.2,Network,A,B,使用缺省路由后，Stub Ne

27、twork可以到達路由器A以外的網絡。,靜態(tài)路由總結,配置靜態(tài)路由的格式： Router(config)#ip route network mask next-hop address 配置默認路由的格式： Router(config)#ip route 0.0.0.0 0.0.0.0 next-hop address 靜態(tài)路由必須在兩個方向上進行配置。 靜態(tài)路由的好處： 管理員可以完全控制路由器路由表的內容。 不會有路由協(xié)議的網絡管理開銷。 比較容易實現。 非常適合小型網絡。,靜態(tài)路由總結續(xù)一,有兩臺路由器的網絡將需要輸入兩條靜態(tài)路由。 有三臺路由器的網絡將需輸入六條靜態(tài)路由。 有100臺路由

28、器的網絡將需要輸入9900條靜態(tài)路由。 N臺路由器網絡的靜態(tài)路由書為N*(N-1)條。,缺點是：網絡可擴展性很差。,靜態(tài)路由 由網絡管理員在路由器上手工添加路由信息以實現路由目的,動態(tài)路由 根據網絡結構或流量的變化，路由協(xié)議會自動調整路由信息以實現路由,靜態(tài)路由和動態(tài)路由,路由協(xié)議,路由協(xié)議 用于路由器選擇路徑和管理路由表。 一旦選擇了一條路徑后，路由器將路由可路由協(xié)議 。,NetworkProtocol,DestinationNetwork,ConnectedRIPIGRP,10.120.2.0172.16.2.0172.17.3.0,Exit Interface,E0S0S1,可路由協(xié)議:

29、 IP、IPX，etc 路由協(xié)議: RIP, IGRP，EIGRP，OSPF,172.17.3.0,172.16.1.0,10.120.2.0,E0,S0,基本功能為 路徑選擇和更新路由表。,自治系統(tǒng) 100,自治系統(tǒng) 200,IGPs: RIP, IGRP,EGPs: BGP,自治系統(tǒng)：內部和外部的路由協(xié)議,自治系統(tǒng)：在同一管理機構的控制下，使用相同的路由 策略的一組路由器的集合（如電信、移動、聯通網絡） IGP在一個自治系統(tǒng)內運行。 EGP連接不同的自治系統(tǒng)。,路由協(xié)議基礎,路由協(xié)議基礎管理距離,管理距離是產生（找到）路由的路由協(xié)議的可信賴程度。 管理距離可以是0到255之間的值。 值越低

30、，路由的可信賴程度越高。 如果到給定目的地有多條路由，管理距離最小的那條路由將被放入路由表中。,路由協(xié)議基礎管理距離續(xù),路由的可信度,IGRPAdministrative Distance=100,Router D,Router B,Router A,Router C,RIPAdministrative Distance=120,E,I need to send a packet to Network E. Both router B and C will get it there. Which route is best?,路由協(xié)議的分類,距離矢量,混合路由,鏈路狀態(tài),C,B,A,D,C,D

31、,B,A,距離矢量的路由協(xié)議概念,根據距離判斷最優(yōu)路徑。 以跳為單位，每經過一臺路由器為一跳。 到指定目的網絡，跳數或度量值最少的為最優(yōu)路由。 矢量是指指向目的網絡的方向。 定期發(fā)送整個路由表到直連的鄰居。 被成為傳說的（謠言）路由。 典型的例子是：RIP、IGRP。,距離矢量的路由協(xié)議,定期將路由表復制給相鄰的路由器,C,D,B,A,C,B,A,D,Routing Table,Routing Table,Routing Table,Routing Table,DistanceHow farVectorIn which direction,初始路由表僅包含直連接口的信息,A,B,C,10.1.

32、0.0,10.2.0.0,10.3.0.0,10.4.0.0,E0,S0,S0,S1,S0,E0,Routing Table,10.2.0.0,10.3.0.0,0,0,Routing Table,10.3.0.0,S0,0,10.4.0.0,E0,0,Routing Table,10.1.0.0,10.2.0.0,0,0,距離矢量收斂,通過向鄰居發(fā)送整個路由表來更新,A,B,C,10.1.0.0,10.2.0.0,10.3.0.0,10.4.0.0,E0,S0,S0,S1,S0,E0,Routing Table,10.1.0.0,10.2.0.0,10.3.0.0,Routing Table

33、,10.2.0.0,10.3.0.0,10.4.0.0,10.1.0.0,0,0,1,1,Routing Table,10.3.0.0,S0,0,10.4.0.0,E0,0,10.2.0.0,1,1,0,0,距離矢量收斂,距離矢量收斂,所有路由器有相同的路由表時，收斂完成。,A,B,C,10.1.0.0,10.2.0.0,10.3.0.0,10.4.0.0,E0,S0,S0,S1,S0,E0,Routing Table,10.1.0.0,10.2.0.0,10.3.0.0,10.4.0.0,Routing Table,10.2.0.0,10.3.0.0,10.4.0.0,10.1.0.0,0,

34、0,1,1,Routing Table,10.3.0.0,S0,0,10.4.0.0,E0,0,10.2.0.0,S0,10.1.0.0,1,2,1,2,0,0,路由循環(huán),距離矢量路由協(xié)議發(fā)送整個路由表。 低速收斂的網絡容易產生路由循環(huán)。 當網絡5失效時，容易使路由器A和B產生環(huán)路。,解決方法：定義最大跳數,指定最大跳數來防止路由自環(huán)。 到達最大跳數時，宣布為目標網絡不可達。 RIP定義一個最大為16的跳數。 不能從根本上解決路由循環(huán)問題。,A,B,C,10.1.0.0,10.2.0.0,10.3.0.0,10.4.0.0,E0,S0,S0,S1,S0,E0,X,解決方法：水平分割,一個接口不

35、會接收由本接口發(fā)送出去的路由信息 RouterA向RouterB發(fā)送10.3.0.0和10.4.0.0的路由信息時， RouterB不會接受。 RouterB向RouterA發(fā)送10.1.0.0和10.2.0.0的路由信息時， RouterA不會接受。 RouterB向RouterC發(fā)送10.4.0.0的路由信息時， RouterC不會接受,A,B,C,10.1.0.0,10.2.0.0,10.3.0.0,10.4.0.0,E0,S0,S0,S1,S0,E0,X,X,X,解決方法：反轉毒性,反轉毒性可以忽略水平分割 當10.4.0.0網絡失效時，RouterC會發(fā)送一個路由中毒消息，并將10.

36、4.0.0網絡設置16跳或不可達。 RouterB收到中毒消息時，發(fā)送一個毒性逆轉的更新到RouterC。 確信所有的路由器都將收到這個中毒的路由消息。,A,B,C,10.1.0.0,10.2.0.0,10.3.0.0,10.4.0.0,E0,S0,S0,S1,S0,E0,X,PoisonReverse,解決方法：Hold-Down 計時,路由器在Hold-Down時間內將該條記錄標記為possibly down以使其它路由器能夠重新計算網絡結構的變化 當收到新的信息或路由被刪除時，路由器將此路由置為擬制狀態(tài)。 當處以擬制定時器的范圍內，路由器不會發(fā)送通告，也不接收路由信息的變化的通告。 可以

37、切斷路由信息的錯誤通告。,Network 10.4.0.0 is down then back up then back down,Update after hold-down Time,Network 10.4.0.0 is unreachable,A,B,C,10.1.0.0,10.2.0.0,10.3.0.0,10.4.0.0,E0,S0,S0,S1,S0,E0,X,Update after hold-down Time,解決方法：觸發(fā)更新,當路由表發(fā)生變化時路由器立即發(fā)送更新信息。 holddown timer 過期。 Another update is received with a

38、 better metric。 可以加速收斂，切斷滿速收斂引起的網絡環(huán)路。,A,B,C,10.2.0.0,10.3.0.0,10.4.0.0,E0,S0,S0,S1,S0,E0,X,Network 10.4.0.0 is unreachable,Network 10.4.0.0 is unreachable,Network 10.4.0.0 is unreachable,10.1.0.0,一個完整的方案,D,B,E,A,X,C,10.4.0.0,一個完整的方案,D,B,E,A,C,X,10.4.0.0,Holddown,Holddown,Holddown,一個完整的方案,D,B,E,A,C,X

39、,10.4.0.0,Holddown,Holddown,Holddown,Poison Reverse,Poison Reverse,Poison Reverse,Poison Reverse,一個完整的方案,D,B,E,A,C,X,10.4.0.0,Holddown,Holddown,Holddown,Packet for Network 10.4.0.0,Packet for Network 10.4.0.0,一個完整的方案,D,B,E,A,C,Link up!,10.4.0.0,一個完整的方案,D,B,E,A,C,Link up!,10.4.0.0,鏈路狀態(tài)協(xié)議,傳遞最佳的路徑信息給其它

40、的路由器,LSP數據包,SPF 運算,拓樸結構數據,最佳路由信息,路由表,C,A,D,B,距離矢量和環(huán)狀路由的綜合應用,混 合 路 由,選擇基于距離矢量的路徑 Converge rapidly using 通過傳遞變化的更新信息 達到快速收斂,平衡的路由,路由器配置 選擇路由協(xié)議 指定網絡或端口,Network 160.89.0.0,Network 172.30.0.0,IGRP, RIP,Network 172.16.0.0,RIP,RIP,IGRP,IP路由的配置任務,指定IP路由協(xié)議,Router(config)#router protocol keyword,指定與路由器直接相連的網絡

41、,Router(config-router)#network network-number,動態(tài)路由配置,Hop 計算，最大支持15跳，16跳即不可達 路由器每隔30秒更新 最多支持相同hop數的6條路徑的負載均衡 RIPV1是有類路由，RIPV2是無類路由 適合以小型網絡 在帶寬不相等負載均衡中，形成瓶頸擁塞,RIP 概 述,RIP時間,Route update timer 每隔30秒向鄰居發(fā)送一個完整路由表的拷貝。 Route invalid timer 宣告路由為無效的時間間隔，通常為180秒。 Holddown timer 某個網絡不可達的更新消息到達時，觸發(fā)。通常為180秒。 Rou

42、te flush timer 當一個路由宣告為無效到從路由表中移出的時間，為240秒。,激活RIP協(xié)議,Router(config)#router rip,Router(config-router)#network network-number,選擇所能到達的網絡 必須是有效的網絡,RIP 配 置,2.3.0.0,RIP 配置舉例,2.3.0.0,172.16.1.1,S2,E0,S3,192.168.1.1,10.1.1.1,10.2.2.2,10.1.1.2,S2,S3,10.2.2.3,172.16.1.0,A,B,C,192.168.1.0,E0,查看RIP信息,RouterA#sh

43、ip protocols Routing Protocol is rip Sending updates every 30 seconds, next due in 0 seconds Invalid after 180 seconds, hold down 180, flushed after 240 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Redistributing: rip Default version control: se

44、nd version 1, receive any version Interface Send Recv Key-chain Ethernet0 1 1 2 Serial2 1 1 2 Routing for Networks: 10.0.0.0 172.16.0.0 Routing Information Sources: Gateway Distance Last Update 10.1.1.2 120 00:00:10 Distance: (default is 120),172.16.1.1,S2,E0,S3,192.168.1.1,10.1.1.1,10.2.2.2,10.1.1.

45、2,S2,S3,10.2.2.3,172.16.1.0,A,B,C,192.168.1.0,E0,查看路由表,RouterA#sh ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1,

46、 E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR T - traffic engineered route Gateway of last resort is not set 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, Ethernet0 10.0.0.0/

47、24 is subnetted, 2 subnets R 10.2.2.0 120/1 via 10.1.1.2, 00:00:07, Serial2 C 10.1.1.0 is directly connected, Serial2 R 192.168.1.0/24 120/2 via 10.1.1.2, 00:00:07, Serial2,172.16.1.1,S2,E0,S3,192.168.1.1,10.1.1.1,10.2.2.2,10.1.1.2,S2,S3,10.2.2.3,172.16.1.0,A,B,C,192.168.1.0,E0,debug ip rip 命令,Route

48、rA#debug ip rip RIP protocol debugging is on RouterA# 00:06:24: RIP: received v1 update from 10.1.1.2 on Serial2 00:06:24: 10.2.2.0 in 1 hops 00:06:24: 192.168.1.0 in 2 hops 00:06:33: RIP: sending v1 update to 255.255.255.255 via Ethernet0 (172.16.1.1) 00:06:34: network 10.0.0.0, metric 1 00:06:34:

49、network 192.168.1.0, metric 3 00:06:34: RIP: sending v1 update to 255.255.255.255 via Serial2 (10.1.1.1) 00:06:34: network 172.16.0.0, metric 1,172.16.1.1,S2,E0,S3,192.168.1.1,10.1.1.1,10.2.2.2,10.1.1.2,S2,S3,10.2.2.3,172.16.1.0,A,B,C,192.168.1.0,E0,阻止RIP傳播,You probably dont want your RIP network ad

50、vertised everywhere on your LAN and WAN. The easiest one is through the passive-interface command. Heres an example of how to configure a passive-interface on a router: Lab_A#config t Lab_A(config)#router rip Lab_A(config-router)#network 192.168.10.0 Lab_A(config-router)#passive-interface serial 0/0

51、,距離矢量路由協(xié)議 使用IGRP的網絡較大，來解決RIP的限制 缺省100hops，最大255hops 支持多路徑 CISCO專有協(xié)議,IGRP 介 紹,IGRP,帶寬 延遲 可靠性 負載 最大傳輸單元,19.2 kbps,19.2 kbps,IGRP 路徑選擇,Source,Destination,IGRP不同于RIP的特征,IGRP用于大型網絡。 IGRP使用自治系統(tǒng)。 IGRP每90秒發(fā)送一個完全路由表。 IGRP在默認情況下，使用帶寬和延遲作為度量。,IGRP Timers,IGRP Timers To control performance, IGRP includes the fo

52、llowing timers with default settings: Update timers These specify how frequently routing-update messages should be sent. The default is 90 seconds. Invalid timers These specify how long a router should wait before declaring a route invalid ifit doesnt receive a specific update about it. The default

53、is three times the update period. Holddown timers These specify the holddown period. The default is three times the update timer period plus 10 seconds. Flush timers These indicate how much time should pass before a route should be flushed from the routing table. The default is seven times the routi

54、ng update period. If the update timer is 90 seconds by default, then 7 90 = 630 seconds elapse before a route will be flushed from the route table.,最多六條路徑 下一次所要到達的路由器必須最接近目的網絡 在允許的參數內選擇路徑,New Route,Initial Route,Source,Destination,IGRP 的不平衡路徑,配 置 IGRP,Router(config-router)#network network-number,指定可

55、以到達的網絡,Router(config)#router igrp autonomous-system,指定IGRP為IP路由協(xié)議,配置 IGRP (續(xù)),Router(config-router)#traffic-share balanced | min ,控制負載平衡數據的分布,Router(config-router)#variance multiplier,控制IGRP的負載平衡,router igrp 100 network 172.16.0.0 network 10.0.0.0,IGRP 配置舉例,router igrp 100 network 10.0.0.0,router ig

56、rp 100 network 192.168.1.0 network 10.0.0.0,Autonomous System = 100,172.16.1.1,S2,E0,S3,192.168.1.1,10.1.1.1,10.2.2.2,10.1.1.2,S2,S3,10.2.2.3,172.16.1.0,A,B,C,192.168.1.0,E0,查看 IGRP 信息,RouterA#sh ip protocols Routing Protocol is igrp 100 Sending updates every 90 seconds, next due in 21 seconds Inval

57、id after 270 seconds, hold down 280, flushed after 630 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Default networks flagged in outgoing updates Default networks accepted from incoming updates IGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0 IGRP

58、 maximum hopcount 100 IGRP maximum metric variance 1 Redistributing: igrp 100 Routing for Networks: 10.0.0.0 172.16.0.0 Routing Information Sources: Gateway Distance Last Update 10.1.1.2 100 00:01:01 Distance: (default is 100),172.16.1.1,S2,E0,S3,192.168.1.1,10.1.1.1,10.2.2.2,10.1.1.2,S2,S3,10.2.2.3,172.16.1.0,A,B,C,192.168.1.0,E0,查看IP路由表,RouterA#sh ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D