[c-nsp] STP to L2 FTTx gear

[Justin Shore]

Given all the STP questions on the list this past week I thought I'd add 
mine to the group while STP is on everyones' minds.

We've recently deployed the beginning of our FTTx offering.  The vendor 
we went with is L2-only (that's a good thing).  The GigE rings have been 
built and the L3 side of things on my 7600s has been built.  I'm meeting 
the FTTx gear with 5 VLANs on 2x 1Q trunks for redundancy from, 1 trunk 
from each 7600.  The 5 VLANs are allowed across the port-channel between 
the 7600s and I'm running HSRP on each SVI.  We didn't set up the trunks 
with a native VLAN.  The config is fairly basic.

interface GigabitEthernet1/9
  description TO FTTx
  switchport
  switchport trunk encapsulation dot1q
  switchport trunk allowed vlan 800,801,811,821,831,851
  switchport mode trunk
  spanning-tree portfast trunk

I'm leaving out the SVIs unless someone thinks their pertinent.  The 
current default spanning tree mode for both 7600s is PVST.  The problem 
I has is that I can't have both physical interfaces (the trunks) turned 
up at the same time.  Doing so causes 2 of my VLANs to go into blocking:

7613-1# sh spanning-tree interface gi1/9

Vlan                Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- 
--------------------------------
VLAN0800            Desg FWD 4         128.9    Edge P2p
VLAN0801            Desg BKN*4         128.9    Edge P2p *PVID_Inc
VLAN0811            Desg BKN*4         128.9    Edge P2p *PVID_Inc
VLAN0821            Desg FWD 4         128.9    Edge P2p
VLAN0831            Desg FWD 4         128.9    Edge P2p
VLAN0851            Desg FWD 4         128.9    Edge P2p

Same thing for the other 7600.  The FTTx vendor set up the hardware to 
not participate in any form of STP on the interfaces facing my 7600s. 
They're running EPS on the GigE rings.  I haven't sniffed this yet to 
prove it but I expect to see all BPDUs leaving Gi1/9 on one 7600 being 
received on Gi1/9 of the other 7600 untouched by what's in the middle.

So, my question is which form of STP would be best for this particular 
scenario?  1d, 1w, PVST, Rapid-PVST or should I be looking at MST?  I 
don't care about load-balancing at the present.  It would be nice is the 
physical link mimicked HSRP but I'm not that picky.  I'm assuming that 
the FTTx vendor could participate in 1d or 1w if I asked but not having 
to have that level of integration could be a good thing.  One less thing 
to troubleshoot when something breaks.

Suggestions?  Thanks
  Justin