Odd RT-AC88U Port Assignments

[Denna]

Per the review below, the Asus RT-AC88U has two switches.

https://www.smallnetbuilder.com/wir...-band-wireless-ac3100-gigabit-router-reviewed
​

Physical ports 1-4 are connected to the Broadcom BCM4709C0KFEBG switch and ports 5-8 are connected to the Realtek RTL8365MB switch.

After connecting devices to each physical port, you can use "robocfg show" to map the physical ports to their internal counterparts.

Ethernet port    Robocfg port
-------------    ------------
Port 1           Port 3
Port 2           Port 2
Port 3           Port 1
Port 4           Port 0
Port 5           Port 5
Port 6           Port 5
Port 7           Port 5
Port 8           Port 5
WAN              Port 4

"robocfg show" reports the ports assigned to the default VLANs.

VLANs: BCM5301x enabled mac_check mac_hash
   1: vlan1: 0 1 2 3 5 7 8t
   2: vlan2: 4 8u

1) When connecting devices to physical ports 5-8, "robocfg show" reports they're all on internal Port 5. Why is that ?

2) Let's say you wanted to isolate each port from the other with private VLANs. You would only be able to assign one private VLAN to physical ports 5-8 since they appear to share the same Port 5 internally, correct ?

3) Why does port 8 appear as tagged in vlan1, but untagged in vlan2 ?

4) The WAN port is on the same switch as the physical ports 1-4, correct ?

 

[RMerlin]

Robocfg only works with Broadcom switches. The ports 5-8 that it lists are internal ports (port 8 for instance is tied to the CPU), not the router's external ports.

There's no way to configure VLANs on the Realtek switch.

 

[Denna]

So if you create a vlan with internal Port 5, it's not really creating a VLAN ?

The source code below isn't compatible with the RTL8365MB, correct ?

https://github.com/RMerl/asuswrt-me.../src/router/shared/sysdeps/ralink/rtkswitch.c​

 

[RMerlin]

So if you create a vlan with internal Port 5, it's not really creating a VLAN ?

Correct. That port is probably just an uplink to the Realtek switch.

The source code below isn't compatible with the RTL8365MB, correct ?

No, different switch models, with different internal registers.

 

[Denna]

@RMerlin,

If you isolated hardware ports 1-4 with private VLANs, does that mean those ports would be isolated from ports 5 - 8 ?

For example:

Port 1 - Isolated from all other ports
Port 2 - Isolated from all other ports
Port 3 - Isolated from all other ports
Port 4 - Isolated from all other ports
Ports 5-8 - Isolated from ports 1-4 only​

 

[RMerlin]

@RMerlin,

If you isolated hardware ports 1-4 with private VLANs, does that mean those ports would be isolated from ports 5 - 8 ?

For example:

Port 1 - Isolated from all other ports
Port 2 - Isolated from all other ports
Port 3 - Isolated from all other ports
Port 4 - Isolated from all other ports
Ports 5-8 - Isolated from ports 1-4 only​

I don't know.

 

[amplatfus]

Robocfg only works with Broadcom switches. The ports 5-8 that it lists are internal ports (port 8 for instance is tied to the CPU), not the router's external ports.

There's no way to configure VLANs on the Realtek switch.

Dear @RMerlin,

I am looking on net to find out if RT-AX88U have only one switch and what kind it is, if it is Realtek.
Please, could you help me with this info?

Thank you very much!
amplatfus

 

[RMerlin]

It has two switches, both Broadcom.