When creating a macvlan with a bridge as parent, interfaces brought up, have NO-CARRIER. Only when connecting another type of interface to the bridge (like a dummy) and bring it up, the bridge and macvlan start forwarding ip netns add tns ip link add tbr type bridge ip link add tmv link tbr type macvlan mode bridge ip link set tmv netns tns ip link set tbr up ip -n tns link set lo up ip -n tns link set tmv up behaviour : kernel 5.4 -> that always works kernel 5.10 -> mostly works, __sometimes__ not kernel 5.14 -> never works verifyable with `ip link show dev tbr` having NO-CARRIER When it doesn't work: ip link add tdum type dummy ip link set tdum master tbr ip link set tdum up and then the bridge and macvlans start forwarding
Apparently the same behavior exists for ipvlan. We upgraded our kernel from 5.4 to 5.10, as more and more need arose for supporting newer hardware, but this different behavior breaks our whole network stack, and is of major concern :-( Can someone please have a look ? Thanks Jan