1. When two routers do not do any routing configuration, R1 ping R2, R1 don't send ARP request, impassability,
2. When R1 configuration of the R2 routing (static) jump for the interface f0/0, R2 does not do the routing configuration, ARP request issued to R1 R2, but R2 does not respond,
3. When R2 also configure R1 under the routing of a jump for the interface f0/0, R2 ARP reply,,
As long as you don't configure the default gateway for the next-hop IP address, and configure it to the interface, the same switches on the two different network segments can be ping, principle with proxy arp close, as long as the router to send arp packets, switch can turn, problem is how to get the arp packets sent out, as long as the next-hop set as the interface to trigger the proxy arp, can achieve the above purpose, do not need something like a single-arm routing,
If I say wrong, please enjoy teasing,