"A" sends the ping for 184.108.40.206 out its Serial0 interface, because the destination of the ping is on the same network as one of "A"'s direct connections. "B" receives the ping on its Serial1 interface, looks at the source IP address, 220.127.116.11, and sends the reply back out Serial1 because that interface is on the same network also. "A" receives the ping reply on its Serial0; you have a successful ping.
Direct-connects work this way, whether IP routing is disabled or enabled: there's no need to route, if the source and destination are on the same IP network.
While this works for the routers themselves, however, it will NOT work for any computers on the Ethernet LANs here because IP routing on the routers is disabled. The routers will not take traffic received on one interface, and send it out on another interface. So it's not a very useful configuration.
"A" pings IP address of Ethernet0 on "B":
If IP routing is not enabled, then both "A" and "B" have no routing protocols to help them learn how to reach remote IP networks and subnets. ("Remote" here means the same thing as "not-directly-connected".) I am not 100% sure that static routes are also unavailable to help the routers find their way; I will have to check this in the lab over the next day or two to confirm. But assuming that static routes are NOT available, then the routers have to rely on the "ip default-gateway" command to process traffic for remote IP networks and subnets.
Perhaps your "A" has a default-gateway that points to the IP address on Serial1 of "B". Then, when "A" pings 18.104.22.168, "A" knows it is not directly connected to that network, so it sends the packet to its default-gateway for forwarding. "B" receives the ping on its Serial1, knows that the destination IP address of the ping is the same as an IP address assigned to one of its own interfaces. "B" decides to reply, looks at the ping's source IP address, 22.214.171.124, and sends the reply back out Serial1 because that interface is on the same network as the device which initiated the ping. "A" receives the ping reply on its Serial0; you have another successful ping.
Following this logic, a successful ping from Serial1 of "B" to 126.96.36.199 to Ethernet0 on "A" would require that the default-gateway on "B" points to the IP address on Serial0 of "A".
This is an interesting exercise in getting two routers to talk to each other without routing enabled. But it doesn't have a practical application, unless the intention is to become familiar with how routers can behave when they are not set up to route. Troubleshooting scenario: Users attached to one of the Ethernet LANs cannot reach servers or users on the other Ethernet LAN, but the routers can ping each other. First question I would ask is: "Is IP routing enabled?"
We have 3 identical switches configured by someone else and would like to claim some of the Gigabit ports(G1/G2/G3/G4) for use on servers. When we try to change the wiring and configuration, we run in to connectivity issues. Attached is a des...
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...