We have a redundant path for some of our communications through a.) a Metro-E provider and b.) two routers forming an L2TPV3 tunnel.

We have Cisco 2960 switches at both ends running RSTP to prevent switching loops and prefer (through costing) our L2TPV3 link over the Metro-E link.

Twice now we've experienced switching loops that took down the network until one link was unplugged.

Will a switch bring an RSTP alt port back up if it quits receiving BPDUs on that port without seeing a physical link change on either port? Our logs reflect no physical link loss on any ports.


You should turn loop guard on those ports... if rstp blocks a port and looses bpdus, it will unblock and form an unmanaged loop unless stp loopguard is on the port. If an rstp port looses bpdus on a loopguard port, the port will disable in a loop inconsistent state until it starts receiving bpdus again.

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