cnMatrix - any way to NOT pass native VLAN traffic through a trunk or hybrid port?

Products cnMatrix
1

Generally in Cisco world it is preferred to NOT permit a native (untagged) VLAN on a trunk link between two switches.

There does not seem to be any way to do this on cnMatrix?

When setting a port to “Trunk”, all VLANs are allowed, and a native vlan must be specified.
When setting a port to “Hybrid,” a native VLAN must still be set, and it is not possible to EXCLUDE the native VLAN from the “allowed” list.

It’s considered a best practice in Cisco world to not pass untagged traffic through a trunk port, so something like this is common:

int gi0/1
description trunk1
switchport mode trunk
switchport trunk allowed vlan 20,30,101

In this scenario, only VLAN 20, 30, and 101 traffic passes. The untagged/native VLAN is technically still VLAN 1 (default), but since it is not included in the “allowed” list, it should not pass through the port.

I can’t figure out a way to set up this sort of arrangement on a cnMatrix switch (specifically, when managed by cnMaestro).

2

Cisco has very specyfic view on VLANs same as Aruba.
Here native is always on.

3

For cnMatrix a trunk port transmits only tagged frames but can receive both tagged and untagged frames. Incoming untagged frames will be treated in the PVID/native vlan. Typically inter-switch traffic via trunk port is always tagged, however, if there is untagged traffic between the switches and you want to drop them, you can create a “discard” vlan (say 1000) on the switch and set the pvid of the trunk port to that dummy vlan. VLAN 1000 will not be a member of any port other than this trunk port. If you want to use hybrid port between the switch, then you need to add vlan 1000 to the port and set the pvid to 1000.

4

If you’ve got multiple trunk ports, does that mean you must create a unique “discard” vlan per port that you want untagged traffic to be dropped on?