802.1Q / gs108t vs gs108tv3

[Freyja]

Hi there,

I have a gs108t switch that broke and while waiting for the replacement I bought a gs108tv3.

Unfortunately, I can't get it to work like the v1 works.

My installation is as follows:

- Port 1 - Tagged (VID 900/1) -> Internet / PLC

- Port 2 - Untagged (VID 900) -> firewall external interface

- Port 3 - Untagged (VID 500) -> DMZ server

- Port 4 - Untagged (VID 500) -> Firewall DMZ interface

- Port 5 - Untagged (VID 1) -> Firewall LAN interface

- Port 6 to 8 - untagged (VID 1) -> LAN

My FW is a Netgate 1100 and the 3 interfaces are actually a switch with different VLANs (all Untagged).

As a result, I only have a single network interface that is shared between the three ports.

The same MAC address is therefore found on all 3 ports of the switch (2, 4 and 5).

The switch obviously doesn't like this, it thinks there's a loop and gives me this error and blocks the interfaces:

PORT-4-ERR_DISABLE rsd_port.c(950) %% loopback-detection error detected on GigabitEthernet4, putting GigabitEthernet4 in err-disable state
PORT-4-ERR_DISABLE rsd_port.c(950) %% loopback-detection error detected on GigabitEthernet2, putting GigabitEthernet2 in err-disable state

In reality, there are no loopback as we are on differents VLANs.

My previous switch (the gs108t) didn't have this problem.

I can't find the parameter to be changed on the gs108tv3 so that it doesn't block ports.

Do you have any ideas?

Thank you.

PS: I've already tried to fake different MAC addresses on the firewall but that's not possible as there is only one physical interface 😞

[schumaku]

The Loop Protection is (like STP or RSTP!) independent of the VLANs. Fact is that these ports can "see" and reach the other ports in a L2 transparent way. The Loop Protection does send out a certain frame type, and does monitor if the same frames are received on other ports. A kind of poor-men's STP 8-)

8-Port Gigabit (PoE+) Ethernet Smart Managed Pro Switch with (2 SFP Ports and) Cloud Management Mode... is your friend - almost 500 pages of great documentation for small switches - p.230 ff "Configure Layer 2 loop protection". You can control it globally, or by port.

[Freyja]

Thanks!

In fact I had already disabled Loop Protection on ports 2 & 4

I've added port 5 and I'll see what happen