CCNP Student lab manual -> question about EIGRP

in CCNP
Hello,
Attached, you have topology that was designed and tested under GNS3.
I want to clarify one thing regarding network convergence (last topic):
When we ping from R3 to R1's loopback interface, best route is through 10.1.1001 (R1's Fa0/0). If I shutdown this interface, it's possible to see that network converges and that packets go to R2 and then through serial link to R1's loopback.
Anyway, "show ip eigrp topology all-links" on R3's does not show this route (R3 - R2 - R1) to R1's loopback interface. It wasn't supposed to appear here?
R3#show ip eigrp topology all-links
IP-EIGRP Topology Table for AS(1)/ID(192.168.100.5)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 10.1.3.0/24, 1 successors, FD is 128256, serno 2
via Connected, Loopback3
P 10.1.2.0/24, 1 successors, FD is 156160, serno 5
via 10.1.100.2 (156160/128256), FastEthernet0/0
P 10.1.1.0/24, 1 successors, FD is 156160, serno 14
via 10.1.100.1 (156160/128256), FastEthernet0/0
Thanks,
AF
Attached, you have topology that was designed and tested under GNS3.
I want to clarify one thing regarding network convergence (last topic):
When we ping from R3 to R1's loopback interface, best route is through 10.1.1001 (R1's Fa0/0). If I shutdown this interface, it's possible to see that network converges and that packets go to R2 and then through serial link to R1's loopback.
Anyway, "show ip eigrp topology all-links" on R3's does not show this route (R3 - R2 - R1) to R1's loopback interface. It wasn't supposed to appear here?
R3#show ip eigrp topology all-links
IP-EIGRP Topology Table for AS(1)/ID(192.168.100.5)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 10.1.3.0/24, 1 successors, FD is 128256, serno 2
via Connected, Loopback3
P 10.1.2.0/24, 1 successors, FD is 156160, serno 5
via 10.1.100.2 (156160/128256), FastEthernet0/0
P 10.1.1.0/24, 1 successors, FD is 156160, serno 14
via 10.1.100.1 (156160/128256), FastEthernet0/0
Thanks,
AF
Comments
P 10.1.1.0/24, 1 successors, FD is 156160, serno 14
via 10.1.100.1 (156160/128256), FastEthernet0/0
The switch has no ip address.
Perhaps the eigrp doesnt run on a switch?
I am not sure as I am studying for ccnp too.
Correct me as I could be wrong.
That route has next hop IP address 10.1.100.1 (the R1's fa0/0) interface.. that means that packets would go R3 -> R1.
Anyway, I thought that, when running "show ip eigrp topology all-links", we should something like:
P 10.1.1.0/24, 1 successors, FD is 156160, serno 14
via 10.1.100.1 (156160/128256), FastEthernet0/0
via 10.1.100.2 (FD/AD), FastEthernet0/0
Because when R1's fa0/0 fails, I could see that packets go through R2 and then from R2 serial interface to R1. Maybe some misunderstanding here?
Br,
AF
Yes, but "show ip eigrp neighbors" command on R3 shows that it has established neighbor relationships both with R1 and R2, so it should be receiving routes from both routers..
Regarding split horizon, I believe that this is only a problem if we are facing frame relay topologies with multipoint subinterfaces. I guess here there's no problem with that...
AF
My ultimate career goal: To climb to the top of the computer network industry food chain.
"Winning means you're willing to go longer, work harder, and give more than anyone else." - Vince Lombardi
Split Horizon is not just for loop prevention in eigrp; it is also used as an efficiency mechanism.
R3#sh ip eigrp topology all-links
IP-EIGRP Topology Table for AS(1)/ID(192.168.100.5)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 10.1.3.0/24, 1 successors, FD is 128256, serno 2
via Connected, Loopback3
via 10.1.100.1 (158720/156160), FastEthernet1/0
via 10.1.100.2 (158720/156160), FastEthernet1/0
P 10.1.2.0/24, 1 successors, FD is 156160, serno 6
via 10.1.100.2 (156160/128256), FastEthernet1/0
via 10.1.100.1 (158720/156160), FastEthernet1/0
P 10.1.1.0/24, 1 successors, FD is 156160, serno 17
via 10.1.100.1 (156160/128256), FastEthernet1/0
via 10.1.100.2 (158720/156160), FastEthernet1/0
P 192.168.100.0/30, 1 successors, FD is 128256, serno 3
via Connected, Loopback11
via 10.1.100.1 (158720/156160), FastEthernet1/0
via 10.1.100.2 (158720/156160), FastEthernet1/0
P 10.1.100.0/24, 1 successors, FD is 28160, serno 1
via Connected, FastEthernet1/0
via 10.1.100.1 (30720/28160), FastEthernet1/0
via 10.1.100.2 (30720/28160), FastEthernet1/0
P 10.1.200.0/24, 2 successors, FD is 40514560, serno 12
via 10.1.100.1 (40514560/40512000), FastEthernet1/0
via 10.1.100.2 (40514560/40512000), FastEthernet1/0
Edit - Just checked to make sure, but if you configure no ip split-horizon eigrp 1 on R2 alone you see 2 paths to R1's loopback.
Now it's explained
AF