Question about the mechanism of RoCEv2 VLAN validation

[liweihang <liweihang@huawei.com>]

Hi All,

I'm confusing at the VLAN validation mechanism of RoCEv2.

Assuming that we have two nodes with an HCA that supports RoCE v2. And we add
a VLAN (id = 1) on each nodes, but they are of different network segments. The
IP and VLAN configuration are as follows:

              NODE_A                                     NODE_B
+--------+---------------+------+          +--------+---------------+------+
| device |     IP        | VLAN |          | device |     IP        | VLAN |
+--------+---------------+------+          +--------+---------------+------+
| eth0   | 192.168.97.1  |   0  |     /----| eth0   | 192.168.100.2 |   0  |
+--------+---------------+------+    /     +--------+---------------+------+
| eth0.1 | 192.168.100.3 |   1  |---/      | eth0.1 | 192.168.98.2  |   1  |
+--------+---------------+------+          +--------+---------------+------+

Now I try to ping eth0 on NODE_B from eth0.1 on NODE_A, of cource it fails
becauce these devices are using different VLAN ID.

Then I do some tests on RoCE, the first one is a simple RC send test:

NODE_A: ib_send_bw -d mlx5_0 -x 5 (the sgid 5 belongs to eth0.1)
NODE_B: ib_send_bw -d mlx5_0 -x 3 <server ip> (the sgid 3 belongs to eth0)

The result is as expected, the RoCEv2 packet with unmatched VLAN ID was
dropped. I think the reason is that for RC service, the VLAN information
of a QP is recorded in QPC, and the HCA can check it when receiving a packet.

But when I run a simple UD send test:

NODE_A: ib_send_bw -d mlx5_0 -x 5 -c UD (the sgid 5 belongs to eth0.1)
NODE_B: ib_send_bw -d mlx5_0 -x 3 -c UD  <server ip> (the sgid 3 belongs to eth0)

The test ends without error successfully. So the question is, RoCEv2 is based
on Ethernet, shouldn't a RoCEv2 node check the VLAN ID of every incoming
packets?

UD is connectionless-oriented, an UD QP won't record VLAN info in it's QPC,
so how to achieve the checking mechanism? Or a UD QP should just ignore the
unmatched VLAN ID?

I didn't find any info from the IB specification, I'd appreciate it if someone
could help explain it.

Thanks
Weihang