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astounding
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Dumb Bridge (P2P) with NO MAC table?

Wed Jun 29, 2011 2:30 am

Is there a way to set up a pair of MikroTik radios in a "dumb" bridge mode such that ZERO MAC table exists in either device, and instead ANY and ALL packets received on the ethernet interface are ALWAYS forwarded out the wireless point-to-point link? (No spanning tree, no mac table, no "learning" at all, instantly in forward-everything mode.) The only exception would be packets with a destination MAC of the device itself.

I know of other manufacturers of P2P radio links that have this mode.

WHY?

If I have two switches at either end of the P2P link handle all the RSTP (doing Cisco-style per-vlan rapid spanning tree) and my P2P bridge devices will transparently pass ALL traffic (including BPDU frames between the Cisco switches), then I can set up P2P redundant links and let Cisco's Per-VLAN RSTP handle fail-over (and even do some load balancing by preferring VLAN X over link A and VLAN Y over link B until there's a link problem).

When the bridge devices are in "smart" bridge mode and "learn" device MACS, then there's always a chance that they'll learn and remember a MAC via the wrong direction (depending on where spanning tree is choosing to block a particular VLAN), which means if there's a link failure, it takes longer for the bridge devices to "re-learn" the new topology of the network and forward correctly. A dumb non-learning bridge is faster and always forwards and makes fail-over super fast in this particular case.

Now if RouterOS was Cisco per-vlan RSTP compatible, perhaps there would be an alternative...

Any ideas?

Thanks!

Aaron out.
 
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astounding
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Re: Dumb Bridge (P2P) with NO MAC table?

Wed Jun 29, 2011 2:55 am

I assume the bridging code when it encounters an unknown MAC forwards to all other bridge ports (much like dumb mode) so I've shortened the timeout and forwarding delay on my bridges to the very minimum. Hopefully that will make the fail-over much quicker.

Aaron out.

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