ping issues

jaykeub

Ok,I know this probably sounds like a real noob question but I have to ask.


Consider the followig scenario:
R1(10.1.1.1)---->(10.1.1.2)R2(10.2.1.1)---->(10.2.1.2)R3
Loopback on R1,R2 and R3 and 1.1.1.1,2.2.2.2 and 3.3.3.3 respectively.
I have placed static routes for the loopbacks on each router to the other 2 routers.
Eg. This is the route from R1 to Lo on R3
ip route 3.3.3.0 255.255.255.0 10.1.1.2
So there are 2 static routes placed on each router.


My problem is that When i try pinging 3.3.3.3 from router1 using 1.1.1.1 as source ( R1# ping 3.3.3.3 source 1.1.1.1) , the ping is successful but when i try pinging from router 1 without a source (R1# ping 3.3.3.3), the ping fails.
My understanding is that when a source is not set in the ping command, the ip of the exit interface ( in this case 10.1.1.2) is used. Since routes are placed to all networks, why does the ping fail ?

Thanks in advance
jake

pham0329

R3 has a route to the 10.1.1.0 network?

Greenmet29

jaykeub wrote: »

Ok,I know this probably sounds like a real noob question but I have to ask.


Consider the followig scenario:
R1(10.1.1.1)---->(10.1.1.2)R2(10.2.1.1)---->(10.2.1.2)R3
Loopback on R1,R2 and R3 and 1.1.1.1,2.2.2.2 and 3.3.3.3 respectively.
I have placed static routes for the loopbacks on each router to the other 2 routers.
Eg. This is the route from R1 to Lo on R3
ip route 3.3.3.0 255.255.255.0 10.1.1.2
So there are 2 static routes placed on each router.


My problem is that When i try pinging 3.3.3.3 from router1 using 1.1.1.1 as source ( R1# ping 3.3.3.3 source 1.1.1.1) , the ping is successful but when i try pinging from router 1 without a source (R1# ping 3.3.3.3), the ping fails.
My understanding is that when a source is not set in the ping command, the ip of the exit interface ( in this case 10.1.1.2) is used. Since routes are placed to all networks, why does the ping fail ?

Thanks in advance
jake

seems like your probably missing a route to 10.1.1.0 in router3, but have a route to 1.1.1.0.

jaykeub

pham0329
Nope.. but R3 has a route to 1.1.1.1

jaykeub

@greenmet29,

M sorry mate but i dint quite get that .. can you please clarify ?

jaykeub

@ greemet29, dont bother replying .. just read ur post again

Do we need to explicitely define a route to the 10.1.1.0 from R3 ?
I was under the impression that since 1.1.1.1 is reachable, the other interfaces also should be , but i see what ya mean .. at work now.. will update later today.. thanks

advanex1

In order to ping the route specified, with static routing, you need to specifically assign a route to that network in R3's routing table and vice versa for R1 needing a route to the 10.2.0.0 or 10.2.1.0 network, however you have it assigned.