Jason Tubnor
2020-Sep-17 00:49 UTC
Fragmentation of em(4) traffic (potentially others) when using vlanhwtag 12.2-BETA1
Hi,
Doing some edge case testing with 12.2-BETA1, I have come across
fragmentation issues when vlanhwtag is enabled on the em(4) network device
(device listed below), causing IPSec traffic moving through a bhyve
'router-on-a-stick' to tank on send. When you disable (-vlanhwtag),
this
issue goes away and full speed send is possible.
Here is a snip of the traffic leaving for the internet after traversing
several VLANs through a bhyve router with vlanhwtag enabled:
10:09:54.173412 Dest.443 > Source.60901: . ack 12384 win 492 <nop,nop,sack
2 {10944:12235} {15373:18253} > (DF)
10:09:54.173936 Source.60901 > Dest.443: . 38413:39873(1460) ack 3837 win
1027 (frag 20228:1480 at 0+)
10:09:54.173937 Source > Dest: (frag 20228:1420 at 1480)
pciconf -vlbc
em0 at pci0:0:25:0: class=0x020000 card=0x308617aa chip=0x15028086
rev=0x04 hdr=0x00
vendor = 'Intel Corporation'
device = '82579LM Gigabit Network Connection (Lewisville)'
class = network
subclass = ethernet
bar [10] = type Memory, range 32, base 0xf7d00000, size 131072,
enabled
bar [14] = type Memory, range 32, base 0xf7d39000, size 4096, enabled
bar [18] = type I/O Port, range 32, base 0xf080, 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
Happy to provide further information if required and perform testing to
make sure the 12.2 release is polished. Thanks,
Jason.