Hey Doug, As you mentioned below, C becomes the designated bridge on segment 3. Therefore it's segment 3 port is no longer a root or alternate port and won't get put into loop-inconsistent state.
cheers, Ben. From: <[email protected]<mailto:[email protected]>> Date: Sun, 4 Mar 2012 05:16:31 -0700 To: IPexpert Online Study List <[email protected]<mailto:[email protected]>> Subject: [OSL | CCIE_RS] LoopGuard theorpy of operation I'm having a little trouble with the theory of operation with LoopGuard. It seems to me that if LoopGuard is enabled, redundancy is lost. For instance, consider 3 switches (A, B, and C) connected in a full layer 2 mesh like a triangle, with A and B comprising a collapsed core, A is root, and C is access with LoopGuard enabled on both non-designated ports as follows: Segment1 A-----------B \ / Segment 2 \ / Segment 3 \ / \ / \ / C My current understanding: In normal operation, B would be the designated port on Segment 3, and transmit BPDU's, and C's port on Segment 3 would be placed in Blocking mode. However, if the link between A and B went down, C would become the designated bridge on Segment 3, while B's port on segment 3 would become a root port and no longer transmit BPDUs. Once BPDUs are no longer received on C's Segment 3 Port, LoopGuard would put it in Loop-Inconsistent state, and B is isolated. B then assumes it is the root, starts sending BPDUs on Segment 3, and then STP converges again on Segment 3 with C having designated port, B having a root port, and the process repeats. I'm obviously missing something here, can somebody clue me in? Thanks! Doug _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
