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station pseudobridge in 3.x

Posted: Tue May 20, 2008 2:43 pm
by Znuff
This doesn't freakin' work. We spent 5 hours trying to figure out WHY our "internet" didn't work on a remote station because our first wireless p2p bridge was using station pseudobridge.

And guess what? We just added WDS and the damn thing worked.

How exactly is station pseudobridge supposed to be working? Can you actually make a transparent bridge with it?

Re: station pseudobridge in 3.x

Posted: Wed May 21, 2008 4:04 pm
by sergejs
It is not true transparent bridge with mode=station-pseudobridge.
It is something similar to MAC-address cloning.

station-pseudobridge - wireless station that can be put in bridge. MAC NAT is performed on all traffic sent over the wireless interface, so that it look like coming from the station's MAC address regardless of the actual sender (the standard does not allow station to send packets with different MAC address from its own). Reverse translation (when replies arrive from the AP to the pseudobridge station) is based on the ARP table. Non-IP protocols are being sent to the default MAC address (the last MAC address, which the station has received a non-IP packet from). That means that if there is more than one client that uses non-IP protocols (for example, PPPoE) behind the station, none of them will be able to work correctly

station-pseudobridge-clone - similar to the station-pseudobridge, but the station will clone MAC address of a particular device (set in the station-bridge-clone-mac property), i.e. it will change itsown address to the one of a different device. In case no address is set in the station-bridge-clone-mac property, the station postpones connecting to an AP until some packet, with the source MAC address different from any of the router itself, needs to be transmitted over that interface. It then connects to an AP with the MAC address of the device that have sent that packet

Re: station pseudobridge in 3.x

Posted: Wed May 21, 2008 11:08 pm
by GP01Fb
I would like to setup my MikroTik router in station-pseudobridge mode too, but I don't know where to start. Can anyone provide a step by step setup guide? Thank you very much for your help.


Re: station pseudobridge in 3.x

Posted: Thu May 22, 2008 4:22 pm
by sergejs
interface wireless set mode=station-pseudobridge band= ssid=,
command you need,

A lot of information is here, ... reless.php

Re: station pseudobridge in 3.x

Posted: Tue Jul 21, 2009 5:14 pm
by JJF
We also battled with the same thing (pseudobridge), but for some reason it only seems to be a problem when the external network is connected to the client side. If the external network is connected somewhere on the AP's side of the bridge, it works fine.

Would there be a reason why the ARP reverse translation does not work properly when routing traffic from the client side?



Re: station pseudobridge in 3.x

Posted: Wed Jul 22, 2009 7:59 pm
by DogHead
My understanding of station-psuedobridge is that it behaves similarly to NAT. The station associates with it's ap and then uses session tracking to translate MAC addressing on it's client side to use it's MAC over the air link. Clone mode does the same thing, but takes the MAC address of the first session established over the link to use for all other traffic.

The problem this creates at the far end is that in ARP one MAC can have many IP addresses associated with it. Generally any kind of MAC layer discovery or management will not pass over this translation. It is for this reason that WDS was created.

If you have a large network or gateway on the client side of the station-psuedobridge you are basically trying to get the station to manage all of the MAC translations. Depending on hardware, this may or may not work. But in general it is just a bad idea.

Use WDS instead, or flip around the station to be your AP. At least then it will be running the MAC translation as designed. Station psuedobridge should only be used for a couple of client devices on the far end, not as a path to a gateway.

Re: station pseudobridge in 3.x

Posted: Thu Jul 23, 2009 1:51 pm
by JJF
Aaah, now that makes a lot of sense, thanks for the nice explanation DogHead. We have indeed moved over to using WDS and it works very nicely.