CIsco Spanning tree issue argh

Hi

I have 3 location A, B, C

A  has

stack cisco WS-C3750X-24 

spanning-tree mode pvst
spanning-tree etherchannel guard misconfig
spanning-tree extend system-id

** I am looking into moving to MST

This is port-channeled to a stack of dell

8024f switches

spanning-tree mode mst
spanning-tree mst configuration

instance 1 add vlan 1

instance 2 add vlan 200-400

instance 3 add vlan 500-600

instance 5 add vlan 10,11,12,13

name "A"

revision 1

B has

2 x WS-C3560G-24PS no stack, but trunked ... (can't stack) each of these has a trunk to  8024F

spanning-tree mode mst
spanning-tree mst configuration

instance 1  vlan 1

instance 5  vlan 10,11,12,13

instance 7  vlan 80-90

instance 8  vlan 90-100

name "B"

revision 1

2x 8024f Dells

spanning-tree mode mst
spanning-tree mst configuration

instance 1 add vlan 1

instance 5 add vlan 10,11,12,13

instance 7 add vlan 80-90

instance 8 add vlan 90-100

name "B"

revision 1

C has

2x 8132f Dells

spanning-tree mode mst

spanning-tree mst configuration

instance 1 add vlan 1

instance 2 add vlan 200-400

instance 3 add vlan 500-600

instance 5 add vlan 10,11,12,13

name "C"

revision 1

I have 3 dark fibe cables to make a ring A -> B -> C -> A

I allow tagged vlans 10,11,12,13 on the dark fibre, running as a stretched vlan

so when i put this together B has a hiss fit. The cisco see PVST mis configure on the ports attached to the dell 8024F and block :( I believe the PVST bpdu packet from the cisco at site A are traversing via vlan 1, I haven't set the untagged vlan id on any of the ports so !!!! I will have to look at that.

I am going to try changing the PVID on the wan port on the 8024f to something apart from vlan1.

Now I have been reading the cisco documentation and it say vlan1 for IST is needed for MST region to MST Region communication, which is going to make it hard

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cfc.shtml#mst_config_region 

So maybe instead of blocking vlan1 on the wan links just between the dell and the cisco's ! 

The document also says that vlan 1 needs to be in instance 0, but the documentation i had read on the dells say instance 1. it also says i need vlan 1 for IST stp ... so that why i need vlan 1 on the wan links.

I am thinking I might just take it out of any instance declaration and let it fall into instance 0.

Now what happens now with site to site traffic

for example

A -> C

vlan 10, its know in both MST regions (A & C) and i believe the inter MST region communication will have both regions saying they know about vlan 10 thats okay no loop. But then add in site B.

so site A will see that C has vlan 10 and site B has vlan 10, lets say it blocks site B port,  can I unblock for certain vlans ? or cause its mst region to mst region its all or nothing.

All this inter region stuff is a pain, i could just go for 1 MST region and have lots of different MSTI, the thing that worries me about this is that I need the VLANS defined on all the switches, thus I am going to have vlans from site b configured in site A and C

Another bit of the puzzle with the 1 MST region is that the wan links only have some of the VLANS associated with them, if site C can't talk to the root bridge for vlan 30 what happens (at least not on vlan 30, cause its not allowed on the wan link)