I have this situation:
PVST+_SWITCH ----- MST_REGION
MST consist of MST0(CST),MST1.MST2 with 20 swtiches
Problem started when I noticed flooding on switches in MST region. I also determined that the source of flooding is that every 35 seconds there are TCN in MST1. I was tracing source of TCN (via show spanning tree detail) and finaly found that source is PVST+_SWITCH ouside od MST region.
1) How switch outside MST region can influence TCN on MST1. Shouldn't MST interact with outside switches via MST0?
2) On PVST+ switch I cant find on either VLAN Topolgy change (there are 5 VLANs). Could it be some software bug on PVST+ switch that sends every 35 seconds TCN?
Also all ports on this switch has either portfast, or portfast trunk.
3) Since PVST+ runs 802.1d does it immeditly clear MAC-address table or it shortens age of mac entry by some factor?
thanks in advance,