【正文】 ions ? Router(config) ? ip routing to enable ip routing on the router (enabled by default) ? no ip routing to disable ip routing on the router ? Router(configif) ? ip splithorizon to enable the splithorizon mechanism. ? no ip splithorizon to disable the splithorizon mechanism. 來自 中國最大的資料庫下載 Interior Gateway Routing Protocol (IGRP) Overview of IGRP IGRP Metrics IGRP Timers IGRP Load Balancing IGRP Configuration 來自 中國最大的資料庫下載 Overview of IGRP (1) ? Cisco proprietary distance vector routing protocol ? All routers must be Cisco routers and using IGRP ? Routing updates at 90 second by default ? Maximum allowable hop count is 255 with a default of 100 ? Classful routing, no sub mask information is sent with the routing updates and all devices in the work must use the same sub mask 來自 中國最大的資料庫下載 Overview of IGRP (2) ? Design emphasizes: ? versatility to automatically handle indefinite, plex topologies ? flexibility for segments having different bandwidth and delay characteristics ? scalability to function in very large works 來自 中國最大的資料庫下載 IGRP Metrics ? IGRP uses the following variables as a metric for determining the best route to an interwork: ? Bandwidth (by default) ? Delay (by default) ? Load ? Reliability ? Maximum Transmission Unit (MTU) ? This is called a posite metric. 來自 中國最大的資料庫下載 IGRP Timer ? Route update timer ? The interval between periodic routing updates (90 sec by default) ? Route invalid timer ? The period that the router hasn’t heard any updates about a particular route (3Xroute update timer, . 270 sec by default) ? Route holddown timer ? The period that the router will not respond to any updates about a particular route (3Xroute update timer + 10 sec, . 280 sec by default) ? Route flush timer ? The period between a route being invalid and its removal from the routing table (7Xroute update timer, . 630 sec by default) 來自 中國最大的資料庫下載 IGRP Load Balancing ? Up to six unequalcost links (where RIP load balancing only for link with same hop count) ? Use bandwidth to determine how to load balance ? Router(configrouter) ? variance to controls the load balancing between the best metric and the worst acceptable metric ? Trafficshare balanced to tell the IGRP routing protocol to share inversely proportional to the metrics ? Trafficshare min to tell the IGRP routing process to use routers that have only minimum costs 來自 中國最大的資料庫下載 IGRP Configuration ? Router(config) ? router igrp autonumous system number to start the IGRP routing configuration mode ? The AS number can be any number from 1 to 65535 ? A router can be a member of as many ASs as you need it to be ? Router(configrouter) ? work worknumber to select participating attached works (not specific sub but the whole work with the work number) 來自 中國最大的資料庫下載 Verifying the IP Routing Configuration show ip route show protocols show ip protocol debug ip rip debug ip igrp 來自 中國最大的資料庫下載 show ip route (1) ? Display the IP routing table ? Example (1): 2621Ash 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, E2 OSPF external type 2, E – EGP i ISIS, L1 ISIS level 1, L2 ISIS level2, *candidate default U peruser static route, o ODR, P periodic downloaded static route T traffic engineered route Gateway of last resort is not set ,1 subs C is directly connected, FastEther0/0 2621A 來自 中國最大的資料庫下載 show ip route (2) ? Example (2): 2501Ash ip route Codes:C connected,S static,I IGRP,R RIP, M – [output cut ] Gateway of last resort is not set ,5 subs S [1/0 ] via S [1/0 ] via S [1/0 ] via C is directly connected,Serial0 C is directly connected,Ether0 2501A The [1/0 ] is the administrative distance and hops to the remote work, which is 0. 來自 中國最大的資料庫下載 show ip route (3) ? Example (3): 2501Csh ip route Codes:C connected,S static,I IGRP,R RIP,M –… [output cut ] … L2 ISIS level2,*candidate default U peruser static route,… Gateway of last resort is to work ,5 subs C is directly connected,Ether0 C is directly connected,Serial0 S*[1/0 ] via 2501C S*, which indicates that this entry is a candidate for a default route. 來自 中國最大的資料庫下載 show ip route (4) ? Example (4): 2621Ash ip route Codes:C connected,S static,I IG