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gbarnes0990

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Linking Cisco Core switches together

Hello,

I have an existing core switch array running 4 x Cisco 3750 Switchs in an array.

I currently have 2 VLANS 220 and 225 running on this switch core. Data and PC's are on 220 and Telephones are on 225.

I need to put in a brand new switch core and to begin with I need to run them in parrallel so I am going to connect the new switch core (4 x Cisco 3850) via a Trunk port to the old switch core. Over that port I was going to allow VLAN's 220 and 225.

I will then start migrating PC's, Telephones and servers over to the new switchcore and eventually switch off the old core.

My question is can I still have VLAN's 220 and 225 on the new core as well? as I need this going forward.

Any gotcha's I need to be mindful of?

Thanks,

Glenn
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Predrag Jovic
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If you have enough cables, space etc.. this can be done in period of 24 hours (or faster if you want - with additional steps) without downtime.
And sure there are assumptions that you are using RSTP instead of STP involved in "no downtime", and that Root bridge is correctly configured etc.
:)
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gbarnes0990

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Thanks,

I don't need to configure DHCP as PC's collect DHCP from the server and Telephones collect IP's from the voice gateway.
I don't need to configure DHCP as PC's collect DHCP from the server
It is DHCP, right? I did not wrote that you need to configure your 3850 or 3750 as DHCP server. Some devices are not checking ARP too often (for example on Cisco switches ARP is checked by default every 4 hours), so this can solve some problems with ARP.
Telephones collect IP's from the voice gateway
This just means that voice gateway is DHCP server for phones.

What you get with this approach is seamless change of your core device...
Sure, you can take any approach you want, this one is just nice and easy way to do it.
Sorry I miss read you comment.
This solves my question.