Have two routers, one subinterface on each serial connected via Cloud using FR; cannot ping each other

[nicolas873]

First of all, this is the first time for me posting on these forums so I hope that my post abides by the rules.

I'm new to configuring Frame Relay and started off with a simple topology:

Since I intend to extend this topology as soon as I've managed to get it working, I decided to use subinterfaces. s0/3/0.103 on R1 and s0/3/0.301 on R2.

R1#sh run
Building configuration...
Current configuration : 848 bytes
!
version 15.1
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname R1
!
!
!
!
!
!
!
!
!
!
!
!
license udi pid CISCO2911/K9 sn FTX15244W9S
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
interface GigabitEthernet0/0
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface GigabitEthernet0/1
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface GigabitEthernet0/2
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface Serial0/3/0
 no ip address
 encapsulation frame-relay
!
interface Serial0/3/0.103 point-to-point
 ip address 10.1.10.1 255.255.255.0
 frame-relay interface-dlci 103
!
interface Serial0/3/1
 no ip address
 shutdown
!
interface Vlan1
 no ip address
 shutdown
!
ip classless
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
 login
!
!
!
end

R2#sh run
Building configuration...
Current configuration : 848 bytes
!
version 15.1
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname R2
!
!
!
!
!
!
!
!
!
!
!
!
license udi pid CISCO2911/K9 sn FTX1524PJ1P
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
interface GigabitEthernet0/0
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface GigabitEthernet0/1
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface GigabitEthernet0/2
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface Serial0/3/0
 no ip address
 encapsulation frame-relay
!
interface Serial0/3/0.301 point-to-point
 ip address 10.1.11.1 255.255.255.0
 frame-relay interface-dlci 301
!
interface Serial0/3/1
 no ip address
 shutdown
!
interface Vlan1
 no ip address
 shutdown
!
ip classless
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
 login
!
!
!
end

Cloud has been configured as follows:

Serial0: DLCI 301 Name zuR2

Serial1: DLCI 103 Name zuR1

Frame Relay:

Serial0 - zuR2 <-> Serial1 - zuR1

Any advice I can get is greatly appreciated.

[Rolf Fischer]

Hi Nicolas,

welcome at CSC!

You're using Frame-Relay, a layer-2 technology, to interconnect the router's subinterfaces.

Why are the subinterfaces in different IP-subnets when there's no routing instance in between?

Actually, due to the logic of FR P2P-interfaces, you could add static routes to make it work; but since you can't specify a next-hop IP-address, you would have to configure the exit-interface instead, which is not recommended:

R1#show ip interface brief s0/0.103
Interface                  IP-Address      OK? Method Status                Protocol
Serial0/0.103              10.1.10.1       YES manual up                    up 
R1#show ip route static
 S       10.1.11.0 is directly connected, Serial0/0.103
R1#ping 10.1.11.1
Sending 5, 100-byte ICMP Echos to 10.1.11.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/37/64 ms

Best regards

Rolf