Redistribution EIGRP and OSPF - GNS3

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redistribute all route from OSPF area 0 into EIGRP 1

R1(config-router)#redistribute ospf 1

But R2 didn’t any route from OSPF routing table

R2>sh ip rou ei
     1.0.0.0/32 is subnetted, 1 subnets
D       1.1.1.1 [90/156160] via 192.168.1.1, 00:20:32, FastEthernet0/0

This is because we need initiate the seed metric for the learned route, if not redistribution not gonna work

R1(config-router)#redistribute ospf 1 metric 100 1 255 1 1500

R2>sh ip rou ei
     1.0.0.0/32 is subnetted, 1 subnets
D       1.1.1.1 [90/156160] via 192.168.1.1, 00:34:24, FastEthernet0/0
     3.0.0.0/32 is subnetted, 1 subnets
D EX    3.3.3.3 [170/25602816] via 192.168.1.1, 00:01:02, FastEthernet0/0
     172.16.0.0/24 is subnetted, 1 subnets
D EX    172.16.1.0 [170/25602816] via 192.168.1.1, 00:01:02, FastEthernet0/0
     10.0.0.0/32 is subnetted, 1 subnets
D EX    10.1.1.1 [170/25602816] via 192.168.1.1, 00:01:02, FastEthernet0/0

From routing table, there’s route to R3 loopback0, 3.3.3.3
Ping the R3 loopback

R2>p 3.3.3.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

Can’t ping? What happen, let’s try traceroute to see where’s the problem
It’s look like the problem is on R1, the trace stop at R1

R2>traceroute 3.3.3.3

Type escape sequence to abort.
Tracing the route to 3.3.3.3

  1 192.168.1.1 40 msec 36 msec 16 msec
  2  *  *  *

The problem is because we only redistribute route from OSPF into EIGRP, but no in the other way
So R3 loopback don’t know how to return the packet it receive from R2
Redistribute from EIGRP to OSPF

R1(config-router)#redistribute eigrp 1
% Only classful networks will be redistributed

Notice the alert in yellow, let see is the router really meant it.. so in this case R3 should only learn classful; 192.168.1.0/24 only, there’ll no 1.1.1.1/32 and 2.2.2.2/32

R3>sh ip rou os
O E2 192.168.1.0/24 [110/20] via 172.16.1.1, 00:02:20, FastEthernet0/1

Yes, they really meant it
Here is the command to make sure that redistribution happen for both classful and classless

R1(config-router)#redistribute ei 1 subnets

R3>sh ip rou os
     1.0.0.0/32 is subnetted, 1 subnets
O E2    1.1.1.1 [110/20] via 172.16.1.1, 00:00:25, FastEthernet0/1
     2.0.0.0/32 is subnetted, 1 subnets
O E2    2.2.2.2 [110/20] via 172.16.1.1, 00:00:25, FastEthernet0/1
O E2 192.168.1.0/24 [110/20] via 172.16.1.1, 00:00:25, FastEthernet0/1

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