1. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-1 Implement an IPv4-Based Redistribution Solution Configuring and Verifying Route Redistribution

2. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-2 Redistribution Supports All Protocols

3. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-3 Steps to Configure Redistribution into RIP Enter router RIP configuration mode  Configure redistribution from another routing protocol; OSPF is used above. redistribute ospf 1 R1(config-router)# R1(config-router)# redistribute ospf 1 ? match Redistribution of OSPF routes metric Metric for redistributed routes route-map Route map reference …  These optional parameters influence redistribution into the RIP routing protocol.

4. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-4 Redistributing into RIP  Redistribute into RIP and assign the metric 3 (3 hops) to all OSPF routes.

5. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-5 Steps to Configure Redistribution into OSPF Enter router OSPF configuration mode  Configure redistribution from another routing protocol; EIGRP with AS 10 is used above.  These optional parameters influence redistribution into OSPF routing protocol. redistribute eigrp 100 metric 100 subnets R1(config-router)# R1(config-router)# redistribute eigrp 100 ? metric Metric for redistributed routes metric-type OSPF/IS-IS exterior metric type for redistributed routes route-map Route map reference subnets Consider subnets for redistribution into OSPF tag Set tag for routes redistributed into OSPF …

6. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-6 Redistributing into OSPF  Redistribute from EIGRP AS 100 into OSPF and change the metric type from type 2 to type 1.

7. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-7 Steps to Configure Redistribution into EIGRP  Enter router EIGRP configuration mode  Configure redistribution from another routing protocol; OSPF with process number 1 is used above.  These optional parameters influence redistribution into EIGRP routing protocol. redistribute ospf 1 R1(config-router)# R1(config-router)#redistribute ospf 1 ? match Redistribution of OSPF routes metric Metric for redistributed routes route-map Route map reference …

8. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-8 Default Metric  The default metric is set to: Bandwidth in kilobits = 10000, Delay in tens of microseconds = 100, Reliability = 255 (maximum), Load = 1 (minimum), MTU = 1500 bytes  You need to use this command when redistributing from another protocol with incompatible metric into EIGRP.  You do not need this command when redistributing: –static routes to interface or connected networks –between EIGRP processes R1(config-router)# default-metric 10000 100 255 1 1500

9. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-9 Redistributing into EIGRP  Redistribute OSPF 1 routing process updates into EIGRP AS 100 and overwrite the default metric.

10. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-10 Example: Redistributing into OSPF - Before Redistribution

11. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-11 Example: Configuring Redistribution at Router R2

12. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-12 Example: Routing Tables After Summarizing Routes and Redistributions

13. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-13 Route SourceDefault Distance Connected interface0 Static route1 EIGRP summary route5 External BGP20 Internal EIGRP90 IGRP100 OSPF110 IS-IS115 RIPv1, RIPv2120 ODR160 External EIGRP170 Internal BGP200 Unknown255 Administrative Distance  Administrative distance (AD) is a way of ranking the trustworthiness of routing information.  A lower administrative distance means a route is more trustworthy.

14. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-14 Administrative Distance Example  From R1 to R6: –RIP (AD 120) will choose R1-R4-R6 –OSPF (AD 110) will choose R1-R2-R3-R5-R6 –EIGRP (AD 90) will choose R1-R2-R3-R5-R6

15. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-15 Steps to Configure Redistribution Using Administrative Distance  Enter router configuration mode  Configure the redistribution from another routing protocol  Modify the administrative distance –Remember that the configuration is different for different routing protocols

16. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-16 distance ospf external 100 inter-area 100 intra-area 100 R1(config-router)# Modifying Administrative Distance  Used for OSPF to define the external, interarea, and intra-area distance  Used for EIGRP to define the internal and external distance  Used for BGP to define external, internal, and local distance distance eigrp 90 170 R1(config-router)# distance bgp 20 200 200 R1(config-router)#

17. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-17 Modifying Administrative Distance (Cont.)  The distance eigrp comand is used for EIGRP protocol.  The distance (IP) command is protocol-independent –Used to define an administrative distance for routes that are inserted into the routing table –Used for all protocols, except for EIGRP, OSPF, and BGP when the dedicated, protocol-specific distance commands are used.

18. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-18 Modifying Administrative Distance (Cont.)  The distance ospf comand is used for OSPF protocol.  The distance (IP) command is protocol independent. –Used to define an administrative distance for routes that are inserted into the routing table. –Used for all protocols, except for EIGRP, OSPF,and BGP when the dedicated, protocol-specific distance commands are used.

19. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-19 Example: Redistribution Using Administrative Distance

20. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-20 Example: Redistribution Using Administrative Distance (Cont.)

21. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-21 Example: Redistribution Using Administrative Distance (Cont.)

22. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-22 Example: Redistribution Using Administrative Distance (Cont.)

23. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-23 Example: Redistribution Using Administrative Distance (Cont.)

24. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-24  Simple redistribution results in a loop after a route is lost.  To prevent routing loops use route maps with: –Redistribution of internal routes only –Route tagging Redistribution to Prevent Routing Loops

25. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-25 Solution With Route Tagging

26. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-26 Redistribution With Tagging Verification  Routing table before tagging

27. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-27 Redistribution With Tagging Verification (Cont.)  Routing table after tagging is applied to router R1

28. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-28 Summary  Redistribution supports all routing protocols. Additionally, static and connected routes can be redistributed to allow the routing protocol to advertise the routes without using a network statement for them.  Administrative distance (AD) is a way of ranking the trustworthiness of routing information. A lower administrative distance indicates that a route is more trustworthy.  The distance (IP) command configures the administrative distance per specific network inserted into routing table, regardless of the IP routing protocol used. The specific protocol dependent distance commands are used to define administrative distance for a specific routing protocol.

29. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-29 Summary (Cont.)  Redistribution using administrative distance can correct path selection problems in a redistribution environment.  It is very likely that routing loops are introduced when you use multipoint two-way redistribution. Two solutions are to redistribute only internal routes and to use route tagging.  The show ip route command output for a specific network shows the tagging values added to a network during the redistribution process.

30. © 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—4-30