Broken ifconfig vlan interface behavior?

[Michael Sierchio]

I seem unable to create a vlan interface with the vlan tag I'd like.  I
can't assign it a vlan tag of 2193.

em2: <Intel(R) PRO/1000 Network Connection 7.3.8> port 0x4000-0x401f mem
0xa3000000-0xa301ffff,0xa3020000-0xa3023fff irq 16 at device 0.0 on pci10

renamed to eth2

Transcript of sorrow:

root at pvpn-tor:~ # ifconfig vlan2193 create vlan 2193 vlandev eth2
root at pvpn-tor:~ # ifconfig vlan2193 inet 10.75.219.1 netmask 255.255.255.0
root at pvpn-tor:~ # ifconfig vlan2193
vlan2193: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu
1500
        options=103<RXCSUM,TXCSUM,TSO4>
        ether 00:00:24:ce:bc:86
        inet 10.75.219.1 netmask 0xffffff00 broadcast 10.75.219.255
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
        vlan: 2193 parent interface: eth2
root at pvpn-tor:~ # ping 10.75.219.1
PING 10.75.219.1 (10.75.219.1): 56 data bytes
^C
--- 10.75.219.1 ping statistics ---
8 packets transmitted, 0 packets received, 100.0% packet loss

Okay, let's try a different VLAN served on that switch port

root at pvpn-tor:~ # ifconfig vlan2193 destroy
root at pvpn-tor:~ # ifconfig vlan2193 create vlan 163 vlandev eth2
root at pvpn-tor:~ # ifconfig vlan2193 inet 10.74.19.151 netmask 255.255.252.0
root at pvpn-tor:~ # ping 10.74.19.151
PING 10.74.19.151 (10.74.19.151): 56 data bytes
64 bytes from 10.74.19.151: icmp_seq=0 ttl=64 time=0.087 ms
64 bytes from 10.74.19.151: icmp_seq=1 ttl=64 time=0.050 ms
^C
--- 10.74.19.151 ping statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.050/0.069/0.087/0.018 ms
root at pvpn-tor:~ # ping 10.74.16.1
PING 10.74.16.1 (10.74.16.1): 56 data bytes
64 bytes from 10.74.16.1: icmp_seq=0 ttl=255 time=1.065 ms
^C
--- 10.74.16.1 ping statistics ---
1 packets transmitted, 1 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 1.065/1.065/1.065/0.000 ms

and it works.

Is this a limitation of the Intel HW VLAN tagging?  ifconfig?  If it is not
to work, why does it permit me to create the interface?

- M