EIGRP - ISIS redistribution demistify

hello all,

I have the following topology: R1 fa0/0 - (eigrp) - fa0/0 R2 fa0/1 (isis) -fa0/0 R3
R1#sh ip int br
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 172.16.12.1 YES NVRAM up up
FastEthernet0/1 unassigned YES NVRAM administratively down down
Loopback0 172.16.1.1 YES NVRAM up up
Loopback48 192.168.48.1 YES NVRAM up up
Loopback49 192.168.49.1 YES NVRAM up up
Loopback50 192.168.50.1 YES NVRAM up up
Loopback51 192.168.51.1 YES NVRAM up up
Loopback70 192.168.70.1 YES NVRAM up up
R2# sh ip int br
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 172.16.12.2 YES NVRAM up up
FastEthernet0/1 172.16.23.2 YES NVRAM up up
Loopback0 172.16.2.1 YES NVRAM up up
Loopback3 3.3.3.3 YES manual up up
R3#sh ip int br
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 172.16.23.3 YES NVRAM administratively down down
FastEthernet0/1 unassigned YES NVRAM administratively down down
Loopback0 172.16.3.1 YES NVRAM up up
Loopback20 192.168.20.1 YES NVRAM up up
Loopback25 192.168.25.1 YES NVRAM up up
Loopback30 192.168.30.1 YES NVRAM up up
Loopback35 192.168.35.1 YES NVRAM up up
Loopback40 192.168.40.1 YES NVRAM up up

All prefixes are /24

on R2 i mutual redistribute between eigrp and isis
R2
router eigrp 1
redistribute isis level-1-2 metric 10 10 10 10 10 route-map FILTER_EIGRP
passive-interface Loopback0
network 172.16.2.0 0.0.0.255
network 172.16.12.0 0.0.0.255
no auto-summary
!
router isis
net 49.0001.2222.2222.2222.00
redistribute eigrp 1 metric 20 route-map FILTER_ISIS metric-type external

R1#sh ip route eigrp
D EX 192.168.30.0/24
[170/256005120] via 172.16.12.2, 00:00:27, FastEthernet0/0
D EX 192.168.25.0/24
[170/256005120] via 172.16.12.2, 00:00:27, FastEthernet0/0
D EX 192.168.40.0/24
[170/256005120] via 172.16.12.2, 00:00:27, FastEthernet0/0
172.16.0.0/24 is subnetted, 4 subnets
D 172.16.2.0 [90/156160] via 172.16.12.2, 02:18:19, FastEthernet0/0
D EX 172.16.3.0 [170/256005120] via 172.16.12.2, 00:00:27, FastEthernet0/0
D EX 192.168.20.0/24
[170/256005120] via 172.16.12.2, 00:00:27, FastEthernet0/0
D EX 192.168.35.0/24
[170/256005120] via 172.16.12.2, 00:00:27, FastEthernet0/0

R3#sh ip route isis
3.0.0.0/24 is subnetted, 1 subnets
i L2 3.3.3.0 [115/20] via 172.16.23.2, FastEthernet0/0
172.16.0.0/24 is subnetted, 5 subnets
i L2 172.16.12.0 [115/94] via 172.16.23.2, FastEthernet0/0
i L2 172.16.1.0 [115/94] via 172.16.23.2, FastEthernet0/0
i L2 172.16.2.0 [115/94] via 172.16.23.2, FastEthernet0/0
i L2 192.168.51.0/24 [115/94] via 172.16.23.2, FastEthernet0/0
i L2 192.168.50.0/24 [115/94] via 172.16.23.2, FastEthernet0/0
i L2 192.168.49.0/24 [115/94] via 172.16.23.2, FastEthernet0/0
i L2 192.168.70.0/24 [115/94] via 172.16.23.2, FastEthernet0/0
i L2 192.168.48.0/24 [115/94] via 172.16.23.2, FastEthernet0/0

R2
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback3
i L2 192.168.30.0/24 [115/10] via 172.16.23.3, FastEthernet0/1
i L2 192.168.25.0/24 [115/10] via 172.16.23.3, FastEthernet0/1
i L2 192.168.40.0/24 [115/10] via 172.16.23.3, FastEthernet0/1
172.16.0.0/24 is subnetted, 5 subnets
C 172.16.23.0 is directly connected, FastEthernet0/1
C 172.16.12.0 is directly connected, FastEthernet0/0
D 172.16.1.0 [90/156160] via 172.16.12.1, 01:44:01, FastEthernet0/0
C 172.16.2.0 is directly connected, Loopback0
i L2 172.16.3.0 [115/10] via 172.16.23.3, FastEthernet0/1
i L2 192.168.20.0/24 [115/10] via 172.16.23.3, FastEthernet0/1
D 192.168.51.0/24 [90/156160] via 172.16.12.1, 01:44:01, FastEthernet0/0
D 192.168.50.0/24 [90/156160] via 172.16.12.1, 01:44:02, FastEthernet0/0
i L2 192.168.35.0/24 [115/10] via 172.16.23.3, FastEthernet0/1
D 192.168.49.0/24 [90/156160] via 172.16.12.1, 01:44:02, FastEthernet0/0
D 192.168.70.0/24 [90/156160] via 172.16.12.1, 01:44:02, FastEthernet0/0
D 192.168.48.0/24 [90/156160] via 172.16.12.1, 01:44:02, FastEthernet0/0

R1#ping 192.168.35.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.35.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 44/111/172 ms
R3#ping 192.168.48.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.48.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

I get all the prefixes on R3 from eigrp BUT i can't ping any of them.
Not a clue why is hapenning this..
any help will be highly appeciated. thanks

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

networker050184

Assuming you had the f0/0 interface up/up when you tried to ping, what source IP address will R3 use when it pings those networks? Answer that and you should have your answer.

billscott92787

networker050184 wrote: »

Assuming you had the f0/0 interface up/up when you tried to ping, what source IP address will R3 use when it pings those networks? Answer that and you should have your answer.

I agree with networker

I definitely seen that your F0/0 on R3 on the config output posted you shown was down and down:

R3#sh ip int br
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 172.16.23.3 YES NVRAM administratively down down

Was this up before you tried to ping?

If it was I can see where R3's ping would reach R1, but what happens when R1 tries to echo back to R3?

catalinu

R3#ping ip 192.168.48.1 source loopback 20

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.48.1, timeout is 2 seconds:
Packet sent with a source address of 192.168.20.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/60/116 ms

So everything is ok..

fa0/0 - was up when i issued the ping

thank you.

billscott92787

Yeah,

Makes sense because R1 did not have a route to the default source address that was being used before when you initially issued the ping. After using the Source loopback 20, R1 has an EIGRP route to that network, so it knows where to route it.