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IDProjectCategoryView StatusLast Update
0000028RouterOS v5[All Projects] Generalpublic2012-10-08 14:52
Assigned Toomega-00 
Status confirmedResolutionopen 
PlatformAllOSRouterOSOS Version5.14
Summary0000028: WDS linking ap-bridge on two MTs leads to broadcast storm
DescriptionThrough ROS 4.17, when we wanted to create a (bridged) wireless backhaul link between RouterBoards, we would bridge the radio and Ethernet (RSTP enabled), configure corresponding radios on each RB to ap-bridge, dynamic WDS, and they would simply connect and work for weeks or months at a time.

As of of ROS 5.x, this same configuration results--sometimes immediately and sometimes after an hour or two of seemingly normal operation--in a packet storm of several Mbps between the APs that effectively makes the remote RBs unreachable. Sometimes even the local board becomes unreachable by Ethernet, and must be power-cycled to log on and disable the radios.
Steps To ReproduceTake two routerboards, running 5.x or 6.x; reset configuration.

Install one radio (confirmed with r52Nm, r52Hn, CM9) in each.

On each RB, create bridge1 with the radio and ether1 as ports; assign IP addresses (on the same subnet as your test network) to the bridge interfaces on the two RBs.

Configure radios to ap-bridge, matching SSIDs and channels, with wds-mode=dynamic and wds-default-bridge=bridge1.

Enable the radios; connect one RB to your network via ether1 and leave the other RB ether1 disconnected.

Monitor traffic across the WDS link. Eventually (sometimes immediately), several Megabits of broadcast traffic will start passing between the two devices and onto the rest of your test network, making one or both of these devices (and possibly other devices on the same subnet) unreachable.
Additional InformationPosted on MT forum:
TagsNo tags attached.




2012-06-01 14:42

reporter   ~0000020

Creating mesh1 rather than bridge1, making wlan1 and ether1 mesh ports, and setting wds-mode=dynamic-mesh seems to put an end to the packet storms. Evidently, when Mesh was added to ROS, a bug was introduced in the Bridge interface.

Unfortunately, Mesh (which uses proprietary HWMP+) is not an option for us because we have non-MT switches throughout our network, and workarounds that use EOIP et. al. are just too cumbersome. Bridging two AP-bridge radios should be trivial.


2012-07-25 13:09

reporter   ~0000021

Issue identified and resolved as of ROS 5.18.


2012-10-08 14:52

administrator   ~0000022

Confirmed in forum reply by MT support

Issue History

Date Modified Username Field Change
2012-06-01 14:35 hotz1 New Issue
2012-06-01 14:42 hotz1 Note Added: 0000020
2012-07-25 13:09 hotz1 Note Added: 0000021
2012-10-08 14:52 omega-00 Note Added: 0000022
2012-10-08 14:52 omega-00 Assigned To => omega-00
2012-10-08 14:52 omega-00 Status new => confirmed