If There's One CCNP BSCI Topic That Looks So Easy But Can Lead To A Real Headache, It's Route Redistribution. I'm Not Even Talking About The Routing Loops And Suboptimal Routing That Can Result When Route Redistribution Is Done Without Proper Planning - I'm Talking About The Basic Commands Themselves. Leaving Out One Single Command Option, Or Forgetting What Else Needs To Be Redistributed When Redistributing Dynamically Discovered Routes, Can Leave You With A Routing Table That Looks Complete But Does Not Result In Full IP Connectivity.In This Free CCNP BSCI Tutorial Series, We'll Take A Look At Three Common Errors In Route Redistribution Configurations, And How To Fix Them. We'll Use Three Routers, R1, R3, And R5. R1 And R5 Are In A RIPv2 Domain And R1 And R3 Are In An OSPF Domain. R1 Will Be Performing Two-way Route Redistribution.R5 Is Advertising Its Loopback, 5.5.5.524, Into The RIPv2 Domain. R1 Sees This Route In Its RIP Routing Table:R1show Ip Route Rip 5.0.0.024 Is Subnetted, 1 SubnetsR 5.5.5.0 1201 Via 100.1.1.5, 00:00:01, Ethernet0For R3 To See This Route, Route Redistribution Must Be Configured On R1. We'll Use The Redistribute Rip Command To Do So.R1(config)router Ospf 1R1(config-router)redistribute Rip Only Classful Networks Will Be RedistributedThe Router Immediately Gives Us A Message That "only Classful Networks Will Be Redistributed". What Does This Mean? Let's Go To R3 And See If That Router Is Receiving This Route.R3show Ip Route Ospf No Output When We Get No Result From A Show Command, That Means There's Nothing To Show. The Only Routes That Will Be Successfully Redistributed With The Current Configuration On R1 Are Classful Networks, And 5.5.5.024 Is A Subnet.To Further Illustrate The Point, A Classful Network Has Been Added To R5. This Network Is 16.0.0.0 8, And Is Now Being Advertised By RIP. R1 Sees This Network As Classful...R1show Ip Route RipR 16.0.0.08 1201 Via 100.1.1.5, 00:00:00, Ethernet0 5.0.0.024 Is Subnetted, 1 SubnetsR 5.5.5.0 1201 Via 100.1.1.5, 00:00:00, Ethernet0... And R3 Is Receiving The Route Through Redistribution.R3show Ip Route OspfO E2 16.0.0.08 11020 Via 172.12.123.1, 00:00:08, Serial0.31To Redistribute Both Classful And Classless Networks, The Option "subnets" Must Be Added To The Redistribute Command On R1.R1(config)router Ospf 1R1(config-router)no Redistribute RipR1(config-router)redistribute Rip SubnetsR3 Will Now See Both The Classful And Classless Networks Being Redistributed Into OSPF. (100.1.1.0 Is The Network Connecting R1 And R5.)R3show Ip Route OspfO E2 16.0.0.08 11020 Via 172.12.123.1, 00:00:20, Serial0.31 100.0.0.024 Is Subnetted, 1 SubnetsO E2 100.1.1.0 11020 Via 172.12.123.1, 00:00:20, Serial0.31 5.0.0.024 Is Subnetted, 1 SubnetsO E2 5.5.5.0 11020 Via 172.12.123.1, 00:00:20, Serial0.31This Is One Of The Most Common Errors Made During Route Redistribution, But Now You Know What To Look Out For! In The Next Part Of This Free CCNP BSCI Tutorial, We'll Take A Look At Another Such Error.
