Unable to ping from spoke to spoke as already disable split horizon on Hub

[Sanjib Pradhan]

Hii..Team,

I have a very small diagarm. R1 acts as Hub and R2,R3 are spoke. Two PVC already enabled between R1-R2(102,201) and R1-R3(103,301). I have configured RIP among all devices. Currently I am unable to ping from R2's loopback address to R'3 loopback address as already disable split horizon on

R1's serial interface.

Please find below output.

R1#sh frame-relay map

Serial0/0 (up): ip 10.1.1.2 dlci 102(0x66,0x1860), dynamic,

              broadcast,, status defined, active

Serial0/0 (up): ip 10.1.1.3 dlci 103(0x67,0x1870), dynamic,

              broadcast,, status defined, active

R1#sh ip route

Gateway of last resort is not set

     2.0.0.0/24 is subnetted, 1 subnets

R       2.2.2.0 [120/1] via 10.1.1.2, 00:00:17, Serial0/0

     3.0.0.0/24 is subnetted, 1 subnets

R       3.3.3.0 [120/1] via 10.1.1.3, 00:00:16, Serial0/0

     10.0.0.0/24 is subnetted, 1 subnets

C       10.1.1.0 is directly connected, Serial0/0

R2#sh ip route

Gateway of last resort is not set

     2.0.0.0/24 is subnetted, 1 subnets

C       2.2.2.0 is directly connected, Loopback1

     3.0.0.0/24 is subnetted, 1 subnets

R       3.3.3.0 [120/2] via 10.1.1.3, 00:00:16, Serial0/0

     10.0.0.0/24 is subnetted, 1 subnets

C       10.1.1.0 is directly connected, Serial0/0

R3#sh ip route

Gateway of last resort is not set

     2.0.0.0/24 is subnetted, 1 subnets

R       2.2.2.0 [120/2] via 10.1.1.2, 00:00:16, Serial0/0

     3.0.0.0/24 is subnetted, 1 subnets

C       3.3.3.0 is directly connected, Loopback1

     10.0.0.0/24 is subnetted, 1 subnets

C       10.1.1.0 is directly connected, Serial0/0

R1#sh ip int s0/0

Serial0/0 is up, line protocol is up

  Internet address is 10.1.1.1/24

  Broadcast address is 255.255.255.255

  Address determined by setup command

  MTU is 1500 bytes

  Helper address is not set

  Directed broadcast forwarding is disabled

  Multicast reserved groups joined: 224.0.0.9

  Outgoing access list is not set

  Inbound  access list is not set

  Proxy ARP is enabled

  Local Proxy ARP is disabled

  Security level is default

  Split horizon is disabled

  ICMP redirects are always sent

  ICMP unreachables are always sent

R2#ping 3.3.3.3 source l1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 2.2.2.2

.....

Success rate is 0 percent (0/5)

Please help me!!!!!!

[Sanjib Pradhan]

Diagram....

[Rolf Fischer]

Hi,

the next-hops of the RIP-routes point to the other spoke's IP-addresses (not to the hub!) and most probably the spokes do not have mappings for the other spoke's IPs.

http://www.cisco.com/en/US/tech/tk713/tk237/technologies_tech_note09186a008014f8a7.shtml#connectspoketospoke

HTH

Rolf

[Sanjib Pradhan]

Dear Rolf,

But in case of Eigrp it's pinging without PVC between spoke to spoke. Why it is required to configured the PVC between spoke to spoke, Already routes learned by RIP(Split horizon disable on R1).

Regards,

Sanjib

[Rolf Fischer]

Sanjib,

this is actually a layer-2 problem.

The hub router and the two spokes share a common network: 10.1.1.0/24

So RIP assumes that every attached host can communicate with each other directly - which would be true with Ethernet, for example.

However, in a Frame-Relay hub and spoke topology, the spokes normally only have layer-2 information to reach the hub.

Some routing-protocols have built-in solutions to overcome this (layer-2) limitation, e.g. OSPF injects host-routes when the network-type is point-to-multipoint. At the moment I can't recall how EIGRP deals with that, but I would assume that it sets the next-hop IP as the hub, not the other spoke.

HTH

Rolf