I am facing Spanning Tree loop issue after i connect two of my 6509 core-switches with Nexus 5010 .
Below are the things which i have covered while configuring however still STP loop appears randmly in FEW VLAN but not in all vlans.
1) Core1-switch Spanning tree root bridge with prioroy of 4096 for all my vlans
2) Core2-switch Spanning tree root bridge with prioroy of 8192 for all my vlans
3) Core1-swich is configured VTP server mode /pwd authentication and & Core2 is VTP client & pwd auth.
4) Nexus switches in Data Centre * HA site have been configued with VTP Transparent mode with only required vlans.
Server required ( Vlan2,11,15,222-227) on Nexus 5010 .
5) HSRP config : Core1 switch : All Vlans priority - 110
Core2 switch : All vlans priority 100 (default)
HA core3 switch : priority 90
6) nexus 5010 is layer2 switch
attaching the diagram for reference....
plz let me know if any of you..have experienced the same problem......experts : plz comment....your recommendations...
Actual Problem : If only either one of Core1 or Core2 is lets assume Core2 forming VPC with N5k switches and Core 1 is not connected to N5k
for VPC connectvitiy then i dont face any STP loop/HSRP L3 interface flapping issue , Howerver as soon as i connect Core1 to N5k using VPC method then after couple of hours the vlans which are allowe to pass through trunk of N5k ( vlan2,11,15,222-227) are Flapping in HSRP in Core1 switch.
6509 core1 ------allowed valn 2,11,15,222-227 in portchannel2 --- Nexus side trunk same vlans allowed
6509 core2 ------allowed valn 2,11,15,222-227 in portchannel3 --- Nexus side trunk same vlans allowed
In HA site we have single N5010 switch and hence no VPC only ether-channel is being used , but I am sure this issue not triggering from HA site.
Root cause : ???