Replacing entire Cisco 3750 Stack with Cisco 9300 Stack

[Rob456]

Hi,

I'm new to Stackwise and I'm currently trying to plan an entire replacement of a two switch stack with new models as part of tech refresh. 

I've read that to replace a member the new switch needs to be running the same model/IOS which isn't the case in my situation, so I'm wondering how to tackle it if I can't replace one at a time whilst maintaining the stack. 

Does anyone have any guidance / procedural steps as the best way to approach this? Services are dual homed on both switches so I'm trying to work out a way to swap one at a time without causing an outage. 

Any guidance appreciated. 

Many thanks.

[balaji.bandi]

You can not mix 3750 with Cat 9300 - it not supported.

Stackcking Guidelines : same Model / Same IOS

When you refreshing with 3750 with Cat 9300 here is the steps :

1. Build new Cat 9300 Stack configuraiton offline - make stacking configuraiton.

2. Copy the Old Config  from 3750 and paste to Cat 9300 ( make sure some syntax may have changed) - align the config as per new Cat 9300 standard.

3. Once the config applied and Liceses applied - no other errors seen

2 Options to cut over from old to new :

Options 1  ( required down time or maintenance window)  - i know you mentioned you want less downtime.

Turn off OLD Switche and add new Switches and test.

Most cases above Option not feasible

Options 2 :

Little Tweak required - how your Uplink connected ( Layer 2 or Layer 3)

If Layer 2 - it easy to connect new stack of Cat 9300 to uplink side allow the respected VLAN in to Port-channel.

Move the devices fom Cat 3750 to Cat 9300 with minimal downtine.

If layer 3, you need to take new Point to Point IP required to be new IP address and follow same proceedure as above.

same test plan, move to new switch and test.

I have said all the steps thinking only Migration point of you, since we dont know your Network how it look and designed.

is this make sense ?

[Rob456]

Thank you for your detailed reply, much appreciated. 

Regarding the migration I have been thinking perhaps the below would work, avoiding the need for an additional L3 up link and any downtime:

1. Remove old master switch, so member switch takes over (all services dual homed).
2. Rack up new master switch and create a trunk to remaining old switch so they can communicate. 
3. Once connected, reconnect all ports that were taken from old master. 
4. Verify connectivity on new switch. 
5. Remove remaining old switch. 
6. Rack up and setup stacking cable for second new switch. 
7. Power up second new switch. 
8. Verify master/ member status. 
9. Reconnect all ports and remove trunks, no longer needed due to logical stack.

Would this work? Any thoughts?

[balaji.bandi]

For now are not sure how your uplink arrangement - i have suggest best approach each method, so you get enough space for testing and role back ?

here is my reply - May be it work - but i dont know your enviroment for now - good to have some HLD to view network

1. Remove old master switch, so member switch takes over (all services dual homed).

BB - Are you removing 3750 Master from stack - how is your uplinks connected ?

      - Instead you can build new Cat 9300 and trunk to Old Switch and Migrate

      - any of the approach, you get small blip of network when you like to move uplink ( depends on L2 or L3 - we dont know at this tage).
2. Rack up new master switch and create a trunk to remaining old switch so they can communicate.

   BB - As i suggested you can still Trunk to old switch and do it.
3. Once connected, reconnect all ports that were taken from old master.

 BB - since you trunk to old switch- still you can balance dual home device 1 to 3750 and 1 to 9300.
4. Verify connectivity on new switch.

5. Remove remaining old switch.

BB - once all devices moved to Cat 9300 - you can take some time and decomm all testing ok.
6. Rack up and setup stacking cable for second new switch.

BB - instead of doing later why not build Stacking from Day 1.
7. Power up second new switch.
8. Verify master/ member status.
9. Reconnect all ports and remove trunks, no longer needed due to logical stack.

BB - Not sure if i get this one ? " no longer needed due to logical stack"

On this step, how is your uplink traffic flowing with new switch or old switch ?

The suggest was made only based on Migration from 3750 to Cat 9300 (new Switch) - if anything i misunderstood requirement please clarify.