I have SG300-20 working in Layer3 mode
VLAN1 is not used
Internet gateway is in VLAN211
Clients are in other VLANs
Switch is default gateway for clients and itself has internet gateway as default route.
MAC address of switch is XX:XX:XX:XX:XX:63
When client sends trafic to Internet destination MAC address in outgoing packets is XX:XX:XX:XX:XX:63
But in incoming packets source MAC address is XX:XX:XX:XX:XX:69
Why does it change? And how can I setup switch to use only XX:XX:XX:XX:XX:63 MAC address?
I have completed the test and found that it does change as expected. When using the switch for layer3 routing, with or without it as your default gateway, this will happen.
I tested from two different vlans in two different ways and each time I pinged through the switch to another subnet the source MAC on the return packet was different on the last two. This caused because the return traffic is going through a different interface on the switch.
At this time there is not an option to change this.