Following the docs on creating VLANs on an Intel i218 NIC:
(with different IP addresses) produces a very slow network on both the non-VLAN and VLAN interfaces. Trying to then destroy the VLAN interface then results in ifconfig and the non-VLAN network interface hanging.
Details on the NIC in question:
em0@pci0:0:25:0: class=0x020000 card=0x85c41043 chip=0x15a18086 rev=0x05 hdr=0x00
vendor = 'Intel Corporation'
device = 'Ethernet Connection (2) I218-V'
class = network
subclass = ethernet
bar  = type Memory, range 32, base rxfbf00000, size 131072, enabled
bar  = type Memory, range 32, base rxfbf22000, size 4096, enabled
bar  = type I/O Port, range 32, base rxf000, size 32, enabled
cap 01[c8] = powerspec 2 supports D0 D3 current D0
cap 05[d0] = MSI supports 1 message, 64 bit enabled with 1 message
cap 13[e0] = PCI Advanced Features: FLR TP
Was this on FreeBSD Head? Or a stable release?
(In reply to Sean Bruno from comment #1)
It was HEAD, but I'm unable to reproduce now, could have been fixed or been a local issue. Thanks for checking, I'll let you know if it occurs again.