Cisco Bug: CSCvs84502 - [22.214.171.124I] MSTP: Ports moving to DSGN/BLK state
Oct 04, 2020
- Cisco ASR 9000 Series Aggregation Services Routers
Known Affected Releases
Symptom: On reloading a MSTP root node with multiple connections to peer routers, the MSTP topology is unstable for 30s before converging. Very high numbers of MAC flushes are requested (see "show spanning-tree mst [instance] topology flushes"). In high scale situations, the port states may get stuck due to the large number of MAC flushes requested. Conditions: Router boot with MSTP configured with a non-zero bring-up delay timer. Note: not all platforms are impacted. This is known to affect NCS5500, but it is likely to impact other similar platforms such as NCS540/NCS560. Higher scale (more interfaces and/or VLANs) will see more network churn and more MAC flushes.
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Bug Details Include
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