Redistribution Routing Protocol (RIP, IGRP, EIGRP, OSPF and Static)

Redistribution:

Redistribution need for more than one routing protocols communication. If my network runs RIP and your network run OSPF. And we want to communication between our networks. Then we need redistribution. Redistribution must do that router, where both protocols are running. 

During Redistribution metric is important, because each protocol use different metric. Like RIP use hop count (maximum 15 hop count. after 15 hops the network will be infinity) and IGRP and EIGRP use composite metric based on bandwidth, delay, reliability, load and MTU.

Now we see the Redistribution between RIP and other Protocols.

RIP configured in R1, R2, R3, R4 and R5. OSPF configured in R5, R6, R7, R8. So after redistribution we see the RIP and OSPF route combination. Now we Configure Router R5 for redistribution. Because RIP and OSPF both run in this router.

Redistribute OSPF into RIP:

R5#conf t

R5(config)#router rip

R5(config-router)#redistribute ospf 5 metric 3

Similarly we can configure other routing protocol (EIGRP, ISIS, IGRP and Static) in RIP.

R5(config-router)#redistribute eigrp 5 metric 3

R5(config-router)#redistribute isis metric 3

R5(config-router)#redistribute igrp 5 metric 3

R5(config-router)#redistribute static  metric 3

Note: Above we define metric value 3. But Cisco recommended using lowest metric value (1). So this route will be available after maximum (14) hop. We can use default metric during redistribution.

Specially see in Image, we use metric value 3 in redistribution. So this network will be valid after next 12 hop (RIP maximum hop count 15). We configured metric value 3 in router R5. So in Router R4 metric value will be 4. Again In router R3 metric value will be 5. Check for network 172.16.78.0. In image.

Again see the below image, we configure metric value with 14, then this network will be traverse next 1 hop. And we can see network 172.16.78.0 is not available in router R2.

R5#conf t
R5(config)#router rip
R5(config-router)#redistribute ospf 5 metric 14

Define Metric Value:Two ways we can define metric value one is above way another is default-metric.

First Way is defining metric value:

R5(config-router)#redistribute eigrp 5 metric 3

2^nd way is default-metric value:

R5(config-router)#redistribute eigrp 5

R5(config-router)#default-metric 1

Redistribute RIP into EIGRP:
EIGRP need five metrics when redistributing other protocols: Bandwidth, delay, reliability, load, MTU.

R5#conf t
R5(config)#router eigrp 5
R5(config-router)#redistribute rip metric 10000 100 255 1 1500     //metric bandwidth delay 
                                                                                                        reliability load MTU

Similarly we can configure other routing protocol (OSPF, ISIS, IGRP and Static) in EIGRP.

R5(config-router)#redistribute ospf 5 metric 10000 100 255 1 1500

R5(config-router)#redistribute isis metric 10000 100 255 1 1500

R5(config-router)#redistribute igrp 5 metric 10000 100 255 1 1500

R5(config-router)#redistribute static  metric 10000 100 255 1 1500

Again We can Define Metric in another way.
First Way is defining metric with parameter:
R5(config-router)#redistribute rip metric 10000 100 255 1 1500
2^nd way is default-metric value:
R5(config-router)#redistribute rip
R5(config-router)#default-metric 10000 100 255 1 1500

After Redistribution, when you enter Router#show ip route . Redistributed route will be show as D EX.



Redistribute RIP into OSPF:
During redistribute other routing protocol in OSPF need to define subnet. Otherwise it redistribute only major network not subnets.

R5#conf t
R5(config)#router ospf 5
R5(config-router)#redistribute rip metric 200 subnets

Similarly we can configure other routing protocol (EIGRP, ISIS, IGRP and Static) in OSPF.

R5(config-router)#redistribute eigrp 5 metric 200 subnets

R5(config-router)#redistribute isis metric 200 subnets

R5(config-router)#redistribute igrp 5 metric200 subnets

R5(config-router)#redistribute static  metric 200 subnets



Redistribute RIP into IGRP:
IGRP also need five metrics when redistributing other protocols: Bandwidth, delay, reliability, load, MTU.

R5#conf t
R5(config)#router igrp 5
R5(config-router)#redistribute rip metric 10000 100 255 1 1500     //metric bandwidth delay 
                                                                                                        reliability load MTU

Similarly we can configure other routing protocol (OSPF, ISIS, EIGRP and Static) in IGRP.

R5(config-router)#redistribute ospf 5 metric 10000 100 255 1 1500

R5(config-router)#redistribute isis metric 10000 100 255 1 1500

R5(config-router)#redistribute eigrp 5 metric 10000 100 255 1 1500

R5(config-router)#redistribute static  metric 10000 100 255 1 1500

During Redistribution one domain all route come to another domain. But sometimes all route are not necessary for other domain or sometimes need to control a specific route path. So we need Policy Based Routing (PBR).