Removing / Adding Switches to LAN

[GRANT3779]

If I remove a switch from a production LAN does this cause STP to be recalculated and risk the network being down during STP computations?

What If I add a new switch to a production LAN? How does STP handle this?

Thanks

[amabdelh]

This will depend on the locatoion of the switch in your network. Is it a primary/secondary root? Is this switch has a root port for other switches? What spanning tree protocol do you use? Just for your info, any changes on your network will trigger TBCN and in some events the switch will clear the mac table and sometimes the root port or root switch will change and that will cause an outage, this all depend on your network topology and configuration

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[devils_advocate]

If its a tail end access switch with no other uplinks going through it to reach the root bridge then it should be fine.

[Parvesh Paliwal]

but if it is root then ??

It will be  boom ... for stp ..

[devils_advocate]

As long as you are using RSTP and its not the root bridge then adding an additional switch will be fine.

[riyaaz000]

Hi GRANT.

<<< If I remove a switch from a production LAN does this cause STP to be  recalculated and risk the network being down during STP computations?>>>>

Yes, any physical change you made in the network will cause STP to re-calculate for a loop free connectivity, thats its job and only part of your network will undergo and outage.

If you are using traditional STP mode, there is no way out, part of the network will be down. If you are using RSTP mode, you wont notice that your network was down.

<<< What If I add a new switch to a production LAN? How does STP handle this? >>>

This also can cause a downtime on part of your network or even your entire network during computation. that depend how you configure the STP (using default values or you hardcoded them)

As a best practice, never use the STP default priority values on your network. because you wont be able to control which switch will be and remains the root bridge.

ex: assume that all your switches have the same priority, later you want to add a new powerfull switch and you want this switch to become your root bridge. The new switch will never become the root bridge, because as all of them have the same priority, that means there is a tie, so to break the tie the switched will elect who has the lowest mac, so one of your old switch will win. keep in mind that every new network device manufacturered have mac addresses in acending order.

Hope that helps..