Observe the topology in the exhibit. HSRP is configured between RTB and RTC with RTC as the active router.
SW2 is configured as the root bridge for the Spanning Tree Protocol. What will happen if the serial connection
of RTC is down?
A.
STP will not need to be recalculated because RTB will take over as active router
B.
RTB and RTC will flap between active and standby because the timers for the STP are greater that the
timers for HSRP
C.
All traffic will automatically forward to RTB
D.
SW3 will take over as the new root bridge
I am not sure that B is the correct answer for this question. When the Serial link on Router C goes down it is a Layer3 link and does not participate in the spanning tree. HSRP can track the interface and lower its priority at the time at link failure. Router B will take over from router C, but no Topology change in spanning tree will occur. Therefor A should be the correct answer.
Maybe I am missing something, if so please let me know.
Thanx
Ian
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I agree, answer B is not correct, SW2 and STP will have no knowledge of a change in L3 topology which occurs outside of their STP domain.
Answer A seems to be the best answer, at least that’s going to be my choice if I see this question on the test when I take it next month.
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I second the responses with the above gentlemen, even though the answer is B in the dumps. Weirdo
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I agree with you.
It does not matter, if the HSRP gateway redundancy is realized with subinterfaces, Bridge virtual interfaces (BVI) or Switch virtual interfaces SVI when using EtherSwitch Network Module (ESW) like NM-16ESW. No change in spanning tree Topology will occur, when the Serial link on Router C goes down. The rules for stp are still the same and regardless of this Change.
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The answer is C.
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agree with Richard, answer would be C I think.
B is obviously wrong as stated above. STP boundaries are layer2, so stop at the layer 3 routers.
answer A is deceiving… it lures you… think about it though… its telling you spanning tree wont converge because rtb is taking over a router…. that’s not correct. spanning tree is not coverging because nothing has changed (nothing to do with rtb).. all the interfaces that were previously up are still up (in its broadcast domain).
Answer C must therefore be correct. RTB becomes hsrp master and starts receiving gateway traffic.
thanks all.
tony.
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