[c-nsp] C6500 issue

[R S]

Hi
I run on C6500 (SUP720) IOS 12.2(33)SXI5 and sometimes I got sporadic problems on production systems that I find really difficult troubleshoot.

The only thing I found strange is the following amount of STP active ports:

#sh spanning-tree summary totals 
Switch is in rapid-pvst mode
Root bridge for: xxx
EtherChannel misconfig guard            is enabled
Extended system ID                      is enabled
Portfast Default                        is disabled
Portfast Edge BPDU Guard Default        is enabled
Portfast Edge BPDU Filter Default       is disabled
Loopguard Default                       is disabled
Platform PVST Simulation                is enabled
PVST Simulation Default                 is enabled but inactive in rapid-pvst mode
Bridge Assurance                        is enabled
UplinkFast                              is disabled
BackboneFast                            is disabled
Pathcost method used                    is short

Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
424 vlans                  228         0        0       4037       4265

I see these number of virtual ports:

#sh vlan virtual-port       
Slot 1
-------
Total slot virtual ports 1954
Slot 2
-------
Total slot virtual ports 1944
Slot 3
-------
Total slot virtual ports 262
Slot 4
-------
Total slot virtual ports 398
Slot 5
-------
Total slot virtual ports 423
Slot 6
-------
Total slot virtual ports 423
Slot 7
-------
Total slot virtual ports 372
Slot 8
-------
Total slot virtual ports 74
Slot 9
-------
Total slot virtual ports 148

Total chassis virtual ports 5998

On slot 1 and 2 I run WS-X6708-10GE.

My questions:
1) Why there is a difference in the total of STP active ports (4265) and vlan virtual port (5998) ?
2) Do you see any overcoming limits in these number ? to me total seems ok, I’m wondering if per slot or per port we overcome the limits
3) could be this issue the root cause of the problem ?

Tks