Source IP Source Mac destination IP destination mac, changes throughout the network.
Local network:
The 1.vlan+mac is addressed in a way that does not cross the gateway. The source IP source mac and destination IP Mac are not changed at this time
2. Over the gateway, the IP routing table is determined. This is just the MAC address where the destination Mac changes to the next hop
Over the outside network:
1. The source address is a public address and the destination MAC address is changed.
2. The source IP address is changed by NAT mode. The destination MAC address is also changed.
Summarize
1. The access control list can be limited to the source IP and destination IP before Snnat. Public network words are easier.
2. No matter how many routers the intranet segment passes through, you can do snat according to his source IP network segment. To surf the net
Source IP Source Mac destination IP destination mac, changes throughout the network