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Beginner

what happens when a cisco switch connected to an existing network of 4 cisco switches

every time i connect a cisco switch to an existing network of cisco switches, all the LEDs color become orange ,and the whole network goes down, then after a while reconnects again.

all the switches are configured

 

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VIP Advisor

Re: what happens when a cisco switch connected to an existing network of 4 cisco switches

It is spanning tree loops may be kicking off..

 

show us the topology and all the switch configuration and explain when did the network goes down, what stage ?

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Beginner

Re: what happens when a cisco switch connected to an existing network of 4 cisco switches

the network goes down once the new switch is connected
VIP Mentor

Re: what happens when a cisco switch connected to an existing network of 4 cisco switches

Hello,

 

make sure the trunk port connecting to the new switch has root guard configured, in order to prevent the new switch to become the root, which would mess up your network. Also, if you run VTP, make sure to set the revision number to 0 (set the switch to vtp mode transparent and then back to mode client) before connecting the switch to your live network...

Beginner

Re: what happens when a cisco switch connected to an existing network of 4 cisco switches


@Georg Pauwen wrote:

Hello,

 

make sure the trunk port connecting to the new switch has root guard configured, in order to prevent the new switch to become the root, which would mess up your network.


sorry for being too late i actually found that the port that's connected to the other switch need to has root guard configured on it then i configured root guard on that port, which already blocked the port but the other switch doesn't cease sending bpdu "which is superior" which keeps the port blocked now i lost the connection to the other network note: we have 2 networks ,one of them is in remote site which i want to connect to my network

VIP Advisor

Re: what happens when a cisco switch connected to an existing network of 4 cisco switches

Hello

It possible you don't have the access ports in a stp portfast state and as such when you introduce the new switch which will create a stp tcn stp puts those access ports into a blocking state until stp convergence has been completed.



kind regards
Paul

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Hall of Fame Community Legend

Re: What happens when connecting a cisco switch to an existing network of cisco switches


@rolly4444 wrote:

Every time i connect a cisco switch to an existing network of cisco switches, the switches LEDs become orange and the whole network goes down, then after a while reconnects again


This is due to spanning-tree loop.


@rolly4444 wrote:

All the switches are configured to vlan1(as the default configuration)


I hope this network isn't in a production because using VLAN 1 is a big no-no.

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