Refer to the following figure. You are configuring a GRE tunnel. However, you cannot ping from Router A to 192.168.3.1. What is the problem?

The routes are wrong. They should be set to the destination of the opposite tunnel IP address and not the serial WAN address. The tunnel numbers do not need to match since they are locally significant to the configuration. The destination on Router A of the tunnel is correct because it points to the serial WAN address on Router B. The serial interfaces do not need to match because they are locally significant to the configuration on each router.