Core switch replacement

[UK-Gary]

Hi, 

 

I'd like to preface this - I am not a networking guy - I know a little, enough for day to day running but that's about it (currently)

 

I'd like to replace my core switch - what is the best practice/process for this? 

 

Configure new switch then swap it our?

Slow migrations to new switch?

Another way?

 

What are the pros/cons for each? 

 

Any thing additional to take in to account?

 

Cheers

 

[Needfuldoer]

What "core switch" are you replacing?

 

Why are you replacing it? To what end?

 

Is this a home install, or a business? 

[RollinLower]

well this question is quite open as it stands now.

are you fine having some downtime when swapping the switch out? then just re-configure and plug the connections over.

do you want the network to stay online during the swap? create new paths and slowly migrate connections over.

 

also, i second the question above. is this for a business?

[UK-Gary]

2 minutes ago, Needfuldoer said:

What "core switch" are you replacing?

 

To what end?

 

Is this a home install, or a business? 

Business - I have explained I'm not an expert but they have said that's fine, just take my time - find he solution and go with it 

 

This is the current layout from what document the guy left behind. SW56 is the current core switch that requires replacing.

I believe is a 3 x 48 port stack 

[UK-Gary]

7 minutes ago, RollinLower said:

well this question is quite open as it stands now.

are you fine having some downtime when swapping the switch out? then just re-configure and plug the connections over.

do you want the network to stay online during the swap? create new paths and slowly migrate connections over.

 

also, i second the question above. is this for a business?

Down time should be fine, I'd so a weekend install.

 

If its a migrations how would I do that? 

[Needfuldoer]

Are all those edge switches only connected by a single gigabit connection to the core? What's connected to those?

 

Do they have 10 gig ports?

 

Again, what model switches are we talking about? Are any of them Layer 3 (and using those capabilities)?

[Blue4130]

17 minutes ago, UK-Gary said:

Hi, 

 

I'd like to preface this - I am not a networking guy - I know a little, enough for day to day running but that's about it (currently)

 

I'd like to replace my core switch - what is the best practice/process for this? 

 

Configure new switch then swap it our?

Slow migrations to new switch?

Another way?

 

What are the pros/cons for each? 

 

Any thing additional to take in to account?

 

Cheers

 

Why do you want to swap it out? What does the current one lack? What do you want from the new one?

[UK-Gary]

[UK-Gary]

This is the core setup - Catalyst 3750G

 

Replacing due to the age

(sorry I was looking at the wrong switch)

[Lurick]

If you're swapping out the chassis then I would recommend doing it as follows:

1) Bring up the new core switch stack or chassis next to or above the current one.

2) Bring the bulk of basic configurations over and map interfaces properly and triple check

3) Diff the configs (AAA, TACACS, RADIUS, SVIs, etc.) and make sure those map properly to the new core switch

4a) If there is any HSRP, routing protocols, etc. then make sure they're ready to go as well

4b) Add connections to the upstream firewall/router/etc. and make sure it forms a routing adjacency with the new core

4c) Check connections come up and you can at least ping out from a SVI or loopback*.

4d) During a maintenance window swap connections one VLAN at a time. Shutdown the VLAN on the old core and bring it up on the new core and then move those connections.

 

*The biggest issue to watch out for is IP conflicts. Make sure any loopback you add doesn't conflict with the existing core switch and that you do one SVI at a time, it's not as simple as doing it linecard by linecard but this way you can shutdown one SVI on the old core, bring it up on the new, and then move those connections more easily.

 

If you've got a big enough window you can skip 4d for the most part and just swap them all at once after shutting down all the SVIs on the old core.

[UK-Gary]

15 minutes ago, Lurick said:

If you're swapping out the chassis then I would recommend doing it as follows:

1) Bring up the new core switch stack or chassis next to or above the current one.

2) Bring the bulk of basic configurations over and map interfaces properly and triple check

3) Diff the configs (AAA, TACACS, RADIUS, SVIs, etc.) and make sure those map properly to the new core switch

4a) If there is any HSRP, routing protocols, etc. then make sure they're ready to go as well

4b) Add connections to the upstream firewall/router/etc. and make sure it forms a routing adjacency with the new core

4c) Check connections come up and you can at least ping out from a SVI or loopback*.

4d) During a maintenance window swap connections one VLAN at a time. Shutdown the VLAN on the old core and bring it up on the new core and then move those connections.

 

*The biggest issue to watch out for is IP conflicts. Make sure any loopback you add doesn't conflict with the existing core switch and that you do one SVI at a time, it's not as simple as doing it linecard by linecard but this way you can shutdown one SVI on the old core, bring it up on the new, and then move those connections more easily.

 

If you've got a big enough window you can skip 4d for the most part and just swap them all at once after shutting down all the SVIs on the old core.

I'll give this a try - I'm still waiting on the new switched to arrive - once they are installed I'll update you. Hopefully no issues

[Lurick]

5 minutes ago, UK-Gary said:

I'll give this a try - I'm still waiting on the new switched to arrive - once they are installed I'll update you. Hopefully no issues

Sounds good, let me know

[Bdavis]

No offense, but I feel pretty comfortable setting up small to midsize networks and wouldn't attempt what you're trying to do. Cisco switches can have crazy complicated configurations. I believe they offer courses with certificates to network professionals. You don't want to be responsible for down time and lost productivity when you can't get Humpty Dumpty put back together again. Any business with this level of network layout should be able to afford to pay a professional to do the swap and configure the switch.