Attached is a JPG of our STP topology for VLAN6, our NFS VLAN. We are running 2 6500 switches as core devices in each of our 2 Data Centers running PVST. We have noticed saturation on the trunk (labeled "A" in the diagram) between the two Core Switches in the Data Center labeled "Data Center 1". We have multiple VLANs trunked between the switches, but we are focusing on VLAN6 in particular because we have noted that NFS VLAN6 traffic constitutes over 50% of total traffic on this trunk. This NFS VLAN 6 is strictly an unrouted Layer2 VLAN (one large broadcast domain).
Our plan is to run another trunk âBâ between the two core switches in DC1, and only pass VLAN 6 tagged frames over this new trunk. To accomplish this we are planning the following:
1) Configure new 802.1Q trunk between the two EDC 6513's and place each side in shutdown mode
2) Add VLAN 6 tag to the new trunk while leaving each side still shutdown
3) Simultaneously remove VLAN 6 tag from the existing trunk while 'no shutting' the new trunk link.
Since this NFS traffic is integral to our business functions, we need to reduce/eliminate the STP re-convergence ripple effect as much as possible. I am worried that once the TCNs are sent out, that they will cause a 50 second outage for VLAN 6 tagged frames throughout our whole campus.
My questions for you (many thanks if you have read this far BTW):
1)From the included diagram, are you able to identify the scope of the STP reconvergence once the VLAN 6 tag is removed from the existing link? Which switches would be affected by this re-convergence?
2) Would uplinkfast/backbonefast reduce the STP reconvergence due to the fact that the new trunk will be forwarding before the 20second max age timer hits?
3) Is there a better way to complete the configuration steps 1-3 that I have noted above that would limit the STP reconvergence?
Thanks in advance!!!
*** EDIT ***
6509-4's root port is incorrectly labeled. Ths correct root port is Gi1/21.