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Mo33ga
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No L2 connection between 2 wi-fi clients

Thu Jun 02, 2022 11:28 am

Hello. It's time to ask noob's questions.
Why does there is no L2 interconnection between 2 wi-fi clients (laptops) which are connected on the same wi-fi interface? Particular on 5GHz iface.
All the data is in config file.
Theese 2 clients are in the same VLAN - 20. They are there via access list. All "forwardings" are set to "yes".
L2 interconnection between theese clients and other wired hosts on VLAN 20 is OK.
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mkx
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Re: No L2 connection between 2 wi-fi clients

Thu Jun 02, 2022 11:56 am

Most of your setup seems fine. There's one thing that might be the problem: you have quite a few devices set to be part of VLAN which is not "native" for wireless interface. This is quite fine for unicast traffic but it doesn't work very well for broadcast frames, I don't know if MT wireless interface is "smart" enough to handle broadcasts in such scenario fully correctly. When one wireless client wants to communicate to another wireless cleint, it needs to discover peers MAC address ... and for that, it sends out ethernet broadcast frame, the intended receiver then replies with unicast frame. If broadcasts are not handled correctly, then the initial frame (request) might not be delivered to intended recipient.

One way to test if my theory above indeed is the problem for you is to create vlirtual AP with separate SSID for clients in VLAN 20. If communication between those clients then works, this would proove that my theory is right.

The other way would be to let clients use default VLAN (i.e. de-activate corresponding entries in /interface wireless access-list) and see if inter-client communication starts to work fine.
 
Mo33ga
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Re: No L2 connection between 2 wi-fi clients

Thu Jun 02, 2022 12:51 pm

Will check it this evening.
 
Zacharias
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Re: No L2 connection between 2 wi-fi clients

Thu Jun 02, 2022 2:41 pm

Maybe you mean VLAN 30?
Your config shows that the wireless cliesnts will be tagged and added to VLAN 30... Unless i miss something obvious.

A comment about your VLANs,
According to the manual On QCA8337 and Atheros8327 switch chips, a default vlan-header=leave-as-is property should be used.
https://help.mikrotik.com/docs/display/ ... switchchip
 
Mo33ga
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Re: No L2 connection between 2 wi-fi clients

Thu Jun 02, 2022 3:12 pm

Maybe you mean VLAN 30?
Your config shows that the wireless cliesnts will be tagged and added to VLAN 30... Unless i miss something obvious.

No. I'm about VLAN 20. Check wireless access-list. The question is about 2 laptops which are in the access list. And they get VLAN 20.
VLAN 30 is "Guest". It is for default auth.

A comment about your VLANs,
According to the manual On QCA8337 and Atheros8327 switch chips, a default vlan-header=leave-as-is property should be used.
https://help.mikrotik.com/docs/display/ ... switchchip

If you're about
set switch1-cpu vlan-header=leave-as-is vlan-mode=secure
then it's not for me. I don't have any untagged frames in my routing core. I use only tagged traffic here in my network. Everything is ok here. But I'll check your variant today evening.
 
Zacharias
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Re: No L2 connection between 2 wi-fi clients

Thu Jun 02, 2022 3:20 pm

No. I'm about VLAN 20. Check wireless access-list.
ok, i saw that now.
 
Mo33ga
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Re: No L2 connection between 2 wi-fi clients

Thu Jun 02, 2022 9:43 pm

The other way would be to let clients use default VLAN (i.e. de-activate corresponding entries in /interface wireless access-list) and see if inter-client communication starts to work fine.

Your theory is right:

Pings:

Host1 - 2.4GHz <-> Host2 - 2.4GHz on VID 30 "Native" - Ok
Host1 - 5GHz <-> Host2 - 5GHz on VID 30 "Native" - Ok, but not right away. ~9 pings "unreachable"

Host1 - 2.4GHz <-> Host2 - 2.4GHz on VID 20 "ACL" - Fault
Host1 - 5GHz <-> Host2 - 5GHz on VID 20 "ACL" - Fault

Host1 - 5GHz <-> Host2 - 2.4GHz on VID 20 "ACL" - Fault - Even more strange 'cause I thought it should work via software bridge "LAN Bridge"

So, is it a bug or a feature? =) Is this bug already known? Maybe it was corrected in modern ROS vers?

According to the manual On QCA8337 and Atheros8327 switch chips, a default vlan-header=leave-as-is property should be used.

But this is for switch-chip. Don't think it will depend. But checking now...
Checked. Nothing happens on Wi-Fi.
 
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mkx
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Re: No L2 connection between 2 wi-fi clients

Thu Jun 02, 2022 10:00 pm

Host1 - 5GHz <-> Host2 - 2.4GHz on VID 20 "ACL" - Fault - Even more strange 'cause I thought it should work via software bridge "LAN Bridge"
The problem with broadcast frames actually pripagates around. When a frame is tagged improperly at some point, nothing can fix it.


According to the manual On QCA8337 and Atheros8327 switch chips, a default vlan-header=leave-as-is property should be used.

But this is for switch-chip. Don't think it will depend. But checking now...

The documentation is a bit too strict. There was a discussion about the matter, even some MT staffers participated, and IIRC the AR8327 switch chip actually ignores setting of vlan-header and works as if it was set to always-strip and according to settings under /interface ethernet switch vlan (so stripping VLAN headers for frames with VLAN ID equal to default-vlan-id). Which is why I'm always setting my access ports with these settings (even though switch chip ignores the setting) just to show what port actually does (leave-as-is doesn't strip headers on egress).
 
Mo33ga
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Re: No L2 connection between 2 wi-fi clients

Sat Jun 18, 2022 1:09 pm

So, colleagues. Is there some solution? Do modern ROSes solve this?

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