topic RE: PSTAG issue in ExtremeSwitching (EXOS/Switch Engine)

PSTAG issue

Alexandr_P — Tue, 04 Dec 2018 22:45:00 GMT

Hello, all!

There is L2 network on X670, all clients receiving VLAN untagged.
At each member port, bind the MAC address of its router and disable the learning.
There are customers who are connected "through" some operator, and the operator, wants to give them service not in his VLAN, but in some other.
Therefore, the PSTAG is very suitable.
The port configuration of the participant looks like this:
# configure vlan "XXX" add ports 1 untagged
# configure vlan "XXX" add ports 1 tagged 1000
Traffic in 1000 VLAN from client must be remapped to VLAN XXX online and vice versa.

As a result, this happens, but at the same time the participant, which is connected in the neighboring port (for example, port 2) and for which the configuration is standard, stops receiving the service.
At the same time, sessions with him do not fail, but traffic falls on their port.
The client in VLAN 1000 works fine and sees the entire network.

For example:
# sh conf | inc "port 1"
configure port 1 rate-limit flood broadcast 1000
configure port 1 vlan XXX limit-learning 0 action stop-learning
create fdb cc??cc:c5:f0:02 vlan "XXX" port 1

# sh conf | inc "ports 1 "
configure ports 1 display-string Client-1
configure ports 1 auto off speed 10000 duplex full
configure sflow ports 1 sample-rate 16384 enable sflow ports 1 ingress
enable lldp ports 1 receive-only

# sh conf | inc "port 2"
disable learning port 2
disable flooding unicast multicast port 2
create fdb aa:aa:aa:d6:77:1d vlan "XXX" port 2
configure vlan XXX add port 2 tagged 1000

So when input command #configure vlan UA-IX add port 2 tagged 1000
Connection with port 1 is strangely disappear - MAC-address is visible, but traffic isn't forward.
When cancel a command, everything is restored.

Scheme below:

Thank you!

RE: PSTAG issue

BrandonC — Tue, 04 Dec 2018 22:56:00 GMT

Maybe I'm misunderstanding this, but it sounds like you are configuring VLAN XXX on port 2 untagged, then coming back and configuring the same VLAN (XXX) with a PS-tag of 1000. Is that correct?

If so, the PS-tag vlan configuration will override the untagged assignment, and only traffic tagged with VLAN ID 1000 will be accepted into VLAN XXX on port 2.

RE: PSTAG issue

Alexandr_P — Tue, 04 Dec 2018 23:18:00 GMT

Hi, Brandon!

Correct me if I'm wrong.
In case of PSTAG

when tagged frames (with tag 1000) came from client to port 2, tag have to cleared and this frames have to be forward in VLAN XXX as untagged to other ports - vlan participants (and vice versa)
untagged frames which came to port 2 have to be accepted only from VLAN XXX

Thank you!

RE: PSTAG issue

Alexandr_P — Tue, 04 Dec 2018 23:38:00 GMT

Let's try more simple:
VLAN XXX = tag 1500
VLAN YYY = tag 1000

#configure vlan XXX add port 2 utagged
#configure vlan XXX add port 2 tagged 1000

In this case on port 2 I can see only untagged frames from VLAN XXX and tagged frames with tag 1000 (which have to be forwarded to VLAN XXX).
Or no?

Thank you!

RE: PSTAG issue

BrandonC — Wed, 05 Dec 2018 03:12:00 GMT

Sorry, looks like I was mistaken on how EXOS would handle that configuration. It looks like it will do what you were expecting it to do, rather than what I was thinking.

I'd say this looks like it is likely a bug of some sort, so it's probably best to open up a case so we can investigate it further.

RE: PSTAG issue

Necheporenko__N — Wed, 12 Dec 2018 14:13:00 GMT

Hello Alexandr,

Have you tried to test the same PSTAG config with default learning and flooding settings?

Best Regards,
Nikolay

RE: PSTAG issue

Alexandr_P — Sun, 16 Dec 2018 23:35:00 GMT

Hello, Nikolay!

Yes, tried - no changes.
Issue is still present.

Thank you!

RE: PSTAG issue

Nishal_Goburdha — Sat, 19 Jan 2019 05:04:00 GMT

hi alexandr,

this does not work for us on x670-G2 (16.1.4.2-patch1-3). so, our policy is not to accept untagged frames on a port that has PSTAG enabled.

i can't tell you why it doesn't work; just that we saw it in the lab, and moved on. sorry.

RE: PSTAG issue

Alexandr_P — Mon, 21 Jan 2019 16:32:00 GMT

Hi, Nishal!

What do you mean? "our policy is not to accept untagged frames on a port that has PSTAG enabled. "

Thank you!

RE: PSTAG issue

Nishal_Goburdha — Tue, 22 Jan 2019 00:42:00 GMT

hi,

for any port that has PSTAGs, enabled, we won't have a corresponding match for an untagged frame. and actually, we do that for single tags too.

for example, we would support:
#configure vlan data add port 2 tagged x
#configure vlan data add port 2 tagged y
#configure vlan voice add port 2 tagged z
[..]

but not:
#configure vlan data add port 2 untagged
#configure vlan voice add port 2 tagged x

in short, if you're going to send us a tagged frame, then other services you want on that port, need to be tagged too.

(yes, of course, it's possible to mix tagged and untagged frames; but this keeps our support queues shorter)