station bridge vs station pseudobridge

RouterOS Wireless Networking
1

I’m testing an emergency solution for the case when an ethernet cable gets unusable and part of the lan becomes unavailable.

I plan to use a Mikrotik router (mAp Lite or RB951***, ROS 7.10 or later) as station bridge to connect to the existing wireless network, which presumably is wired to the working part of the lan. The AP could be Mikrotik or Tp-Link, so I was testing mode=station-pseudobridge. In the working part there is is a DHCP server, allways Mikrotik, which can be also the AP but not allways. So far everythings looks fine: I made a separate lan consisting of 3 swithces with webfig function, a pc and the Mikrotik wireless station that connects to the working lan.

There are some comment in the forum regarding this kind of use of station pseudobridge, stating that it won’t work, if there are several clients behind the station they won’t get ip address especially when the AP is the DHCP server itself, or they won’t be accessible from the rest of the lan …

Am I missing something or just misunderstood why pseudobridge is not the way to go?

2

Here’s an article describing different station modes … and discussing problems with pseudobridge.

3

I’ve read that and then I realized that either it is wrong or I do not understand. The discussion side is empty.

My test environment:
—[AP]-( )-[STA]—[Y]
X : the main network, there is my pc and the DHCP server,
AP: TP-Link access point,
STA: mikrotik mAp Lite, wifi mode=station-pseudobridge,
Y: test network consisting of three switches that have webfig, another mikrotik router (M) and a pc.

And it works!
The manual states that pseudobridge mode “should be avoided when possible” and:

“This mode is limited to complete L2 bridging of data to single device connected to station”: I’ve connected 5 devices,

“bridging of non-IP protocols to more than one device will not work”: each of the 5 devices from Y and the station got ip from the DHCP server, the M router and the STA was reacheable from my pc by mac address with winbox.

“Also MAC address translation limits access to station device from AP side to IPv4 based access”: from my pc the webfig on each of the 3 switches were accessible at the same time, the share on the pc was acessible, the M router and the station were reacheable by ip with winbox.

I didn’t find anything that does not work.

4

Be happy but don’t be surprised if in a subsequent version of ROS it does not work anymore…

Can you show config on map Lite ?
Curious…

5

Well, exactly that kind of surprise I’m trying to avoid.

The configuration is the default + setting bridge ports, the SSID, password and mode. Only routeros package installed.

# 2023-12-18 10:15:06 by RouterOS 7.11.2
# software id = 
#
# model = RBmAPL-2nD
# serial number = 
/interface pwr-line
set [ find default-name=pwr-line1 ] disabled=yes
/interface bridge
add admin-mac=78:9A:18:30:23:48 auto-mac=no comment=defconf name=bridgeLocal
/interface wireless
set [ find default-name=wlan1 ] band=2ghz-b/g/n channel-width=20/40mhz-XX country=romania disabled=no frequency=auto mode=\
    station-pseudobridge ssid=Netis
/interface lte apn
set [ find default=yes ] ip-type=ipv4 use-network-apn=no
/interface wireless security-profiles
set [ find default=yes ] authentication-types=wpa-psk,wpa2-psk mode=dynamic-keys supplicant-identity=MikroTik
/ip hotspot profile
set [ find default=yes ] html-directory=hotspot
/interface bridge port
add bridge=bridgeLocal comment=defconf ingress-filtering=no interface=ether1
add bridge=bridgeLocal interface=wlan1
add bridge=bridgeLocal interface=pwr-line1
/ip settings
set max-neighbor-entries=8192
/ipv6 settings
set disable-ipv6=yes max-neighbor-entries=8192
/interface ovpn-server server
set auth=sha1,md5
/interface wireless cap
set bridge=bridgeLocal discovery-interfaces=bridgeLocal interfaces=wlan1
/interface wireless connect-list
add interface=wlan1 mac-address=1C:61:B4:1B:29:68
/ip dhcp-client
add comment=defconf interface=bridgeLocal
/routing bfd configuration
add disabled=no interfaces=all min-rx=200ms min-tx=200ms multiplier=5
/system identity
set name=RouterOS
/system note
set show-at-login=no
6

I would like to know as well. I read in the online documentation that wifi-qcom does NOT support mesh, and therefore, this may be my only option.
NoMesh.png
https://help.mikrotik.com/docs/spaces/ROS/pages/8978441/HWMPplus+mesh

7

Interestingly enough station bridge is now working, where earlier it was not until I switched it to station pseudobridge
Now I switched it back and it works fine.

For anyone wondering though, the difference between station bridge and station pseudobridge is:
Station Pseudobridge:
Normal AP connections do not use 4-address header information, and therefore source MAC addresses are lost (you need 2 for the radio MACs, and 2 for the src/dest MACs). Therefore pseudobridge does MAC NAT (for lack of better terms). So everything looks like it is coming from one MAC address.

Station Bridge:
This is only compatible with other wifi-qcom devices. It hooks to another device in AP mode and will create a 4-address connection. Therefore MAC NAT is not needed. The documentation is not clear about this at all, that one side needs to be in AP mode and the other side in Station Bridge mode.
From whatI can tell, this is pretty much equivalent to WDS on other wifi brands. Except somehow Mikrotik made it proprietary for wifi-qcom. I don’t know why, but this is what it is.