[c-nsp] VTP/STP/TRUNK

Shaun mailinglists at unix-scripts.com
Sun Dec 18 03:55:25 EST 2005


I have a 3750 connected to multiple 2950G's, 3750 is running as VTP Server 
V1 with pruning enabled.  The 2950G's are trunked to the 3750 and run VTP as 
a client.  One of my 2950G's recently through this error at me.

%SPANTREE_VLAN_SW-2-MAX_INSTANCE: Platform limit of 64 STP instances 
exceeded. No instance created for VLAN153 (port Fa0/1).

I understand the error, STP is enabled on too many interfaces for this 
device but this switch only has probably different vlans assigned to it. 
After further investigation I found that a sh int <port> trunk on both the 
2950 and the 3750 showed different info.

2950G
    Port        Vlans in spanning tree forwarding state and not pruned
    Fa0/1       1-2,20,50,60-61,95-119,121-153,155-158

3750
    Port        Vlans in spanning tree forwarding state and not pruned
    Fa1/0/13    1-2,60,97-99,115,120,122,133,137-138,141-142,144,153

As you can see the 2950 is showing more vlans on the trunked port than the 
3750 is showing.  Is this normal?  Shouldn't they match?

Just to clarify I'm not restricting vlans on the trunked interfaces on the 
3750.

I also ran this same test on a different 2950 that's trunked to the 3750 and 
the results where backwards on that switch.  The 2950 showed fewer vlans on 
the trunked port than the 3750 showed..

I verified I have the right ports to the right switches by doing a sh cdp 
nei

Thanks in advance.

-- 

~Shaun 





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