Outgoing VLAN traffic
This uses the MAC address of the switch as the source MAC address in packet headers. The MAC address configured on VLAN interfaces is not used on outbound VLAN traffic.
ARP Sender MAC address field
Source MAC address field in the Ethernet frame header
ARP Sender MAC address field
Source MAC address field in the Ethernet frame header
To hosts in the network, VLAN traffic continues to be routed (using the reconfigured MAC address as destination address), but outbound VLAN traffic appears to be sent from another router attached to the same subnet (using the Switch MAC address as source address) attached to the same subnet. Although it appears as an asymmetric path to network hosts, the MAC address configuration feature enables Layer 3 VLAN migration. (A successful VLAN migration is achieved because the hosts do not verify that the source MAC address and the destination MAC address are the same when communicating with the routing switch.)