hi,

i have 2 buildings between which runs a cable connected to 2 Cisco Switches in either building.

this switches have multiple VLAN's working on them and the cable mentioned above is a Trunk.

i need to keep a Wireless RB-SXT PTP connection between the buildings in case the cable gets severed (cut) the trunk should start working through the RB-SXT wireless PTP.

can i please get to know which is the best configuration to achieve the above? also do i need to plug the SXT into the trunk port? or can it start working on any other port forwarding all VLAN's?

Make the bridge. The vlans will pass thru like with the wire. You don't need anything special for it.

i did the bridge but it just passes traffic for only one VLAN (probably the one it is plugged in)

i am just not understanding how can i go about it.

i did the bridge but it just passes traffic for only one VLAN (probably the one it is plugged in)

i am just not understanding how can i go about it.

connect both SXTs to trunk ports on their respective switches. The SXTs can only pass traffic that is sent to them, and the switch is what is stopping other VLANs' traffic from reaching the SXTs.

Saint I think you are overthinking the solution to trunking the VLANS.
All you do is run either of the wireless bridge into a trunk port and the vlans will pass through.Note you will start a network loop the moment this goes online.Just think of the bridge as a long trunk ethernet uplink.

To make it work as a backup link you are going to have to use some flavor of Spanning Tree and use higher port costs to influence l2 path selection.My experience has not been great dealing with the cisco's proprietary spanning tree methods and industry standard stp/rstp.

hi,

i did the same and the client has replied the following when he took the trials on a weekend :

As per our telephonic discussion last weak ; today I had connected your devices on both side in Trunk Port of switches.
After that it was not worked for both VLANs. Then I had connected both devises to VLAN209. It was also not worked.
When I had connected to VLAN200 then it worked for only for VLAN200.

I am suggesting you please check you devices for Trunk Port accessibility.

the result above is out of VLAN200 to VLAN 212.

now i am wondering what the hell is wrong?

Make sure both SXT are in AP-bridge / station-bridge mode, and have ether1 and wlan1 connected to a bridge. It really should be that simple.

As for spanning tree, if the two switches are running spanning tree on their interfaces connected to the wireless bridge, then your link should appear identical to any other simple cable (except of course that it can't go at wire speed).

Also make sure that the l2mtu for the interfaces >= 1508

Make sure both SXT are in AP-bridge / station-bridge mode, and have ether1 and wlan1 connected to a bridge. It really should be that simple.

As for spanning tree, if the two switches are running spanning tree on their interfaces connected to the wireless bridge, then your link should appear identical to any other simple cable (except of course that it can't go at wire speed).

Also make sure that the l2mtu for the interfaces >= 1508

hi zerobyte... thank you very much for the reply.

the wireless bridge is working perfectly fine... ironically even when connected to the Trunk Port (on Cisco Switch) only one VLAN passes through it.

i have not checked the L2MTU interface settings though but would that make so much of a difference?? and how to identify if the Cisco Switch is running a Spanning Tree??

In Cisco:
show spanning-tree interface Fa0/1 (or whatever the interface designation is)

Eg: When you have the cable and the wireless bridge attached, you should see a status like BLK or Altn instead of Root... you might also want to set the spanning tree cost on the interface to the wireless bridge so that the switches know for sure that this is a slower / less-preferred interface:
http://www.cisco.com/web/techdoc/dc/ref ... _cost.html


Also make sure the interfaces are actually running as trunks and are allowed to pass all vlans.... versus
(voice vlan is enabled on 1/0/23 which is why it shows two vlans)

i have not checked the L2MTU interface settings though but would that make so much of a difference?? and how to identify if the Cisco Switch is running a Spanning Tree??

If the L2MTU is not large enough, then 802.1q vlan tagged frames could be dropped... the tag adds 8 bytes to the frame size.

In Cisco:
show spanning-tree interface Fa0/1 (or whatever the interface designation is)

Eg:

Code: Select all

cisco#show spanning-tree int g1/0/25

Vlan                Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0001            Root FWD 4         128.25   P2p
VLAN0100            Root FWD 4         128.25   P2p
VLAN0101            Root FWD 4         128.25   P2p
VLAN0196            Root FWD 4         128.25   P2p
VLAN0198            Root FWD 4         128.25   P2p
VLAN1970            Root FWD 4         128.25   P2p
VLAN1971            Root FWD 4         128.25   P2p
VLAN1972            Root FWD 4         128.25   P2p
VLAN1973            Root FWD 4         128.25   P2p

When you have the cable and the wireless bridge attached, you should see a status like BLK or Altn instead of Root... you might also want to set the spanning tree cost on the interface to the wireless bridge so that the switches know for sure that this is a slower / less-preferred interface:

Code: Select all

cisco# config t
cisco(config)#interface Gi1/0/1
cisco(config-if)#spanning-tree cost 500

http://www.cisco.com/web/techdoc/dc/ref ... _cost.html


Also make sure the interfaces are actually running as trunks and are allowed to pass all vlans....

Code: Select all

cisco#show int po3 trunk

Port        Mode             Encapsulation  Status        Native vlan
Po3         on               802.1q         trunking      1

Port        Vlans allowed on trunk
Po3         1-4094

Port        Vlans allowed and active in management domain
Po3         1,100-101,196,198,403,800,900,1970-1973

Port        Vlans in spanning tree forwarding state and not pruned
Po3         1,100-101,196,198,403,800,900,1970-1973

versus

Code: Select all

cisco#show int g1/0/23 trunk

Port        Mode             Encapsulation  Status        Native vlan
Gi1/0/23    off              802.1q         not-trunking  1

Port        Vlans allowed on trunk
Gi1/0/23    101,196

Port        Vlans allowed and active in management domain
Gi1/0/23    101,196

Port        Vlans in spanning tree forwarding state and not pruned
Gi1/0/23    101,196

(voice vlan is enabled on 1/0/23 which is why it shows two vlans)

hey thanks a ton for this... i owe you a beer!!

btw.... just in case the port is running as trunks and but are not allowed to pass all vlans what should be the alternative on Mikrotik side? if any...

btw.... just in case the port is running as trunks and but are not allowed to pass all vlans what should be the alternative on Mikrotik side? if any...

Mikrotik's bridge pretty much acts the same as an unmanaged switch would - it just passes the tags along and doesn't know or care what they mean, so it really won't interfere with vlan tagging unless you went in and purposely blocked it by using bridge filter rules or else changed the vlan mode on a switch menu option (I don't think the sxt has a hardware switch in it anyway, so this couldn't possibly apply in that case)

sounds great!!! now let me take the field trial when the client is having a off day... can't work on live network.

and yes I still owe you a Beer!!! Cheers!

sounds great!!! now let me take the field trial when the client is having a off day... can't work on live network.

and yes I still owe you a Beer!!! Cheers!

Heh - well, you can rate my post in lieu of a beer and we'll call it even (customs would hold the beer for too long anyway).

One thing you can try is just moving the cable to the ports you plan to use for the wireless bridge and putting the wireless bridge in the ports that are already configured and working - see if the problem follows the switch ports or follows the wireless bridge. If the switches are configured properly, they're not going to care which is the wire and which is the bridge.

Oh - I think personally, I would disable STP/RSTP on the wireless bridge and let the Ciscos handle it - Mikrotik's STP is single-tree, while Cisco uses PVST by default (a spanning tree running on each vlan)

i have also been reading about using WDS so do you think it will make any difference?

i have also been reading about using WDS so do you think it will make any difference?

WDS is meant for mesh networking, and really wouldn't be the right solution for a point to point link.

Wds has some disadvantages but can make fully transparent bridges unlike many other modes. Nevertheless I would avoid using it if not absolutely necessary.

You would only need WDS if the MAC addresses behind the station bridge are showing up as the station's own MAC address, and the other bridging modes don't fix this.

Since you're using Mikrotik gear as the bridge, make sure the AP is set to mode "ap bridge" and the station is set to "station bridge"
(I hope I've remembered that right)

The WDS mode will create a sort of "tunnel" on the wlan, where all MAC addresses behind the ethernet interface of the client will appear on the WDS interface in the bridge hosts display, while the station itself will appear on the wlan1 interface.

I'm not sure why the advice is to avoid WDS in this kind of scenario - I know why WDS is less-than-desirable when making a mesh type of infrastructure, but when the "next hop" of the WDS client is ethernet, then that removes the drawbacks that I'm aware of... Namely, cutting the available air-time of the wds client in half, but since it's not actually repeating anything on wireless, this doesn't happen.... Maybe there's an overhead caused by WDS that I'm not aware of...