On the same subnet, no packet will send to router for communication of two host.
To understand VPN, I explain two kind of links:
Point To Point: The link is between two devices,not more. It's same as Water Pipe. If you strew some water from one side,it will come out from other side.
Multi-Access: A device's interface will see more than a device can communicate.
Ethernet is Multi-Access link, more than two device can be connected to an Ethernet switch (typical switch which these days used). So source device need to specify destination device address in data link layer (destination MAC address in Ethernet header). Therefore, Ethernet uses ARP to get MAC address of destination node
VPN is Point-To-Point link, packet send from one side, will come out from other side. Any address (IP, MAC, ...) which destination has,it will receive the packet. So VPN does not require ARP and destination IP address is not important (does not require to be in the same subnet mask)
If you see a VPN unencrypted packet with Wireshark, you will see two network layer headers,but one datalink header! Because VPN is point to point,so second data link layer header has no effect.
VPN uses a tunnel. Real packets are routed, but outside the tunnel, it's as-if it was local, and thus uses ARP. – mveroone – 2013-09-02T14:34:47.780
Traffic on the same subnet will not go via the router. It's only when you want to leave the subnet the gateway(router) will be used. – Qben – 2013-09-02T14:35:57.100
Possibly relevant reading: http://serverfault.com/questions/49765/how-does-ipv4-subnetting-work
– Hennes – 2013-09-02T14:43:25.533IP address is not sufficient. Please specify subnet mask. These IP addresses can be in the same subnet or not, according to the subnet mask used. – SuB – 2013-09-02T20:17:06.117