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Cisco Bug: CSCtc68613 - MSTP:Flush optimizations required for Network convergence scenarios

Last Modified

Jan 29, 2017

Products (1)

  • Cisco ASR 9000 Series Aggregation Services Routers

Known Affected Releases


Description (partial)


Under some circumstances, MSTP on IOS-XR can perform MAC flushes when not strictly required.  This means that in some network topologies there can be more flooding than is strictly required.  If links are oversubscribed, this may lead to some traffic loss until MAC addresses are re-learned.


MSTP on IOS-XR follows the behavior defined in the IEEE 802.1Q-2005, and as such will perform a MAC flush for all MSTIs whenever a port moves to Forwarding state, even if some MSTIs are not actually affected by the topology change.
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