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2610-PWR port blocked by STP

Tpelley
Occasional Visitor

2610-PWR port blocked by STP

I have a 2610-pwr that shows ports being blocked by stp for no apparent reason.

The switch is used to power voip phones on all 48 user ports. port 52 is used as the only up-link to the adjacent switch. A typical log event looks like.

ports: port 44 is now off-line
ports: port 44 is Blocked by STP
ports: port 44 is now on-line

given that there is an IP phone on each port so in theory the link status of the port should never change, what could be causing this flapping.

LACP is disabled and the STP portion of my config is as follows.

spanning-tree
spanning-tree priority 10

assuming that I do not have a multitude of defective phones, what should I be looking for?

3 REPLIES
Matt Hobbs
Honored Contributor

Re: 2610-PWR port blocked by STP

That's normal when a port comes first comes online (i.e, phone plugged in). Ignore it.
Tpelley
Occasional Visitor

Re: 2610-PWR port blocked by STP

Thanks Matt, but It has to be something other than that as these phones have been is service for weeks.

On occasion when this happens a port will flap continuously for an hour or two and then stop as suddenly as it starts.

I also see no log entries suggesting that power has stopped being delivered to the port and then resumed which implies that the phone has remained physically connected.

Cheers
Matt Hobbs
Honored Contributor

Re: 2610-PWR port blocked by STP

Are users affected? If not, relax!

Maybe there are some other spanning-tree issues occurring higher up that's causing the ports to go through a quick spanning-tree learning process. You could try forcing them to admin-edge-port.