Comment 9 for bug 1213173

> If it IS an issue with the kernel building a new version of libpcap and tcpdump will not help.

If it's an issue with the kernel changing the way it handles VLAN tags - i.e., whether it leaves them in the packet data, so that the filter code in the kernel sees them as part of the packet data, or whether it removes them and puts them into metadata that has to be tested specially by a BPF program - then a new version of libpcap *could* help, as libpcap was recently changed to deal with that problem.