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Vlan interfaces goes down due to STP .Plz help

fariha zain
Level 1
Level 1

Hi Experts,

I would like to know if there is STP recalculation caused vlans to bounce on the switch.

Eg:

SwitchA-----Port-channel-------SwitchB-----SwitchC

I have couple of vlans on all th switches. Portchannel is layer 2 between A and B.

but when I shut down the portchannel between the switches I see the vlans which are active on the Switch B going down and come back online

Even the vlans which are active and up between switch B and C are too going down when i shut down the port channel.

Example:

Vlan 30

ip address 30.0.0.3 255.255.255.0

sh vlan id 30

ports Po1, Gig 3/1 ( gig 3/1--connecting to Switch C)

Error:

Port channel down-->

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan30, changed state to down

%LINK-3-UPDOWN: Interface Vlan30, changed state to up

: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan30, changed state to up

Question:

========

Why is this Vlan going down and coming up online?

Is this due to STP recalculation?

I could see some rootchange happening when i shut down the port-channel. Hence want to know does this vlan bounces bcz of STP recalculation?

Regards

Fari

2 Replies 2

fariha zain
Level 1
Level 1

Any update on this please?

Which switch is the actual gateway for the vlans having the issue?

Which switch is the spanning tree root?

Can you post the config of the EtherChannel?

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