Connecting Cisco to unmanaged LAN

[juskel706]

My office has a few unmanaged, non-Cisco switches.  I have been tasked with adding a recently acquired Catalyst 2960X-24TS-L to the LAN, and to configure it.  So here are my questions:

First,

If my PC is on the LAN, and connected to the new Cisco switch via console cable only, is there anyway to accidentally screw up anything on the LAN? 

Second,

If I connect the Cisco switch to the LAN before configuring it, is there anyway to accidentally screw up anything on the LAN?  

Thanks for any help in advance.

[doodles6970]

Hi,

Reading between the lines here I’m picking up a few things. If the switches are not managed then it looks like everything will just be VLAN 1.
Plugging an in configured Cisco switch into this environment will just mimic what you have in all honesty.
Having the console cable plugged into the switch will definitely not break your lab. ( unless you configure something via the console)

What’s the end game here? Are you just adding this switch to provide capacity or are you slowly changing the network.

Thanks,

Ryan

[paul driver]

Hello

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@juskel706 wrote:

If my PC is on the LAN, and connected to the new Cisco switch via console cable only, is there anyway to accidentally screw up anything on the LAN? 

No unless the new switch is also connected tot the lan which I guess it wont be

Second,

If I connect the Cisco switch to the LAN before configuring it, is there anyway to accidentally screw up anything on the LAN?  

Possibly yes - It all depends on your existing environment and if the this "new" switch is a spare switch from another area which hasn't been properly cleaned ,a small chance it could overwrite your exiting vtp database running on your network but again it all depends on the current setup regards your network in relation to the vtp database

However saying that if you are just running a flat network or the switch is brand new then this wouldn't happen.

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res
Paul

[juskel706]

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doodles6970

wrote:

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What’s the end game here? Are you just adding this switch to provide capacity or are you slowly changing the network.

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Both.  For now, just adding it for capacity.  In the future, we are going to be looking into setting up vlans.  I'm sure that'll be rough.

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@paul driver wrote:

Hello

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@juskel706 wrote:

If my PC is on the LAN, and connected to the new Cisco switch via console cable only, is there anyway to accidentally screw up anything on the LAN? 

No unless the new switch is also connected tot the lan which I guess it wont be

Second,

If I connect the Cisco switch to the LAN before configuring it, is there anyway to accidentally screw up anything on the LAN?  

Possibly yes - It all depends on your existing environment and if the this "new" switch is a spare switch from another area which hasn't been properly cleaned ,a small chance it could overwrite your exiting vtp database running on your network but again it all depends on the current setup regards your network in relation to the vtp database

However saying that if you are just running a flat network or the switch is brand new then this wouldn't happen.

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It's a new switch, so it hasn't been configured. 

Thanks for the help, time to plug her in.

[Joseph W. Doherty]

"If my PC is on the LAN, and connected to the new Cisco switch via console cable only, is there anyway to accidentally screw up anything on the LAN?"

So, the new switch would not be connected to any of your existing LAN topology? Then (as also noted by the others), no, you don't risk any impact to you existing LAN.

"If I connect the Cisco switch to the LAN before configuring it, is there anyway to accidentally screw up anything on the LAN?"

Yes. It also depends how you connect it to your existing LAN. Also, if you do configure the switch ahead of time, the same applies. I.e. depending how the switch is configured and how it's connected could impact your existing LAN. The only real difference, if you connect the switch before you configure it, you really don't know how the switch is currently configured, whereas if you do preconfigure it, you then know how the switch is configured, but that doesn't preclude it being configured incorrectly.

As noted by the others, if the switch has a default configuration, it shouldn't cause any issues if you connect it to your LAN, provided you only make one connection.

BTW, unsure the 2960X has one, but some of the later Cisco switches have a management Ethernet port that you can connect to your network. This to provide in-band access to the switch. However, often the switch needs to be configured to use that port. Connecting this port to your network also generally precludes any impact to the rest of your LAN.