I've posted previously around high-level thoughts about migrating from CCM 3.3(3) to CUCM 6.1 (new cluster)
I've been able to spend time with our chosen migration vendor, and things seem to be a lot clearer to me now :o) However, I am still unsure about some things, and was wondering if anyone can suggest any 'Best Practice' solutions?
1 - How do we successfully 'stage' the migration between clusters? I am looking to migrate users via subnets, so we can control the areas that are migrated to 6.1 simply by altering the "option 150" tftp pointer on our DHCP server. However, i'm not sure how best to route callers from the old system to the new. We will use an ICT between them, but how do i structure the ICT so that there is intelligence such that an internal/external call into the OLD cluster will route to a user who is now on the NEW cluster? (ie caller on 3.3 calls an extension that is now on 6.1. What sort of config is needed on the ICT or Route Patterns to point at the new cluster BUT avoid calls falling into a loop and trying to get back over the ICT)
2 - im concerned that we dont have signed XML downloads at present, so any migration (big bang or staged) would not be possible to roll-back from if we needed to. (CCM 3.3 doesnt support signed loads?, so the phones wont be able to talk back to 3.3 if we re-point them at 3.3 in the event of a roll-back)
3 - I will move one of our E1 lines (outbound) into the new cluster by registering the CMM with that CallManager. However, how can i get inbound calls working on the new cluster in a staged migration? I can move an inbound E1 too, but how will our carrier know which extensions have moved to send calls to that E1? Would Inbound have to stay on the old cluster until we fully migrate and move ALL the E1s to the new CUCM 6.1? (using some clever route pattern across the ICT???)
I might have some other migration-related Q's too - sorry! :) I've supported CCM for years but never worked on a migration before, so this is all new territory for me :o(