Please refer to the diagram. All the switches are 6500. I have 2 server access switches connected to 2 distribution switches in a U via L2 trunks.
I would like to upgrade the L2 port-channel between Server access switch I & II from 1 gig links to 10gig links. I want to make sure that there is zero(minimal) downtime when I upgrade it.
I have tried 2 different methods to achieve this:
i) Create a new 2x10gig port channel between the two access switches & allow vlans 2 & 3 on it while it is in shutdown mode. Now, I shutdown the old 2x1gig port channel & enable the new port channel almost instantaneously. Obviously, I will be doing it from console connection. Using this method, there is a downtime of 30seconds while the spanning tree reconverges & hsrp goes active-active on both the distribution switches during that time.
ii) Create a new 2x10gig port channel between the two access switches & allow vlans 2 & 3 on it. This will create a spanning-tree loop between the access switches & recalculation happens as a result of this. All the vlans then(after reconvergence) become FORWARDING on the 20gig port channel but block 1 vlan each on the old 2gig port channel. During this reconvergence period of 30sec, the hsrp goes active-active on both the distribution switches & hence causes 30sec downtime. Once the reconvergence is done, I shutdown the old port channel.
I am unable to think of a better way to do this. Can anyone suggest a way to accomplish this with minimal downtime ? We are running PVST as per our standards & cannot go to RPVST which would have reduced the downtime.
Thanks in advance.
