Adding a switch in VLAN

[ali.asghar]

If I have a working network, for example (2) 3550 switches are connected to (2) 6509s. The first 3550 is in VLAN 10 connected to both 6509s, and the second 3550 is in VLAN 11 again connected to both 6509s. I like to add one more 3550 (24) ports in VLAN 10 and the other (24) ports in VLAN 11. As I assume this new switch will run STP Calculations to determine which uplink ports should go into the forwarding/Blocking mode since the switch is connected to both Core 6509s.

My question is will it interrupt the already working VLANs 10 and 11 since STP will have to be rerun for this new switch only. If it will then I will have to do this after hours if not then my job will be easier.

[daniel.bowen]

Before you plug in the switch, set the bridge priority to a figure higher than the current root bridge. Otherwise, the new switch may force a root bridge election and could cause disruption to the rest of the network plus leave you with an undesirable root bridge.

Other than this, the effect should be minimal

Daniel,