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Edge port continuously switching between Port-offline and blocked by STP

 
TsAmE
Occasional Contributor

Edge port continuously switching between Port-offline and blocked by STP

Hello. I have a computer1 connected to ip phone which is connected to an HP J9625A switch like this:

switch <-> ip_phone <-> computer1

l have been continuously receiving snmp traps close to 10000 traps with the followng traps on computer2:

port 4 is now off-line

port 4 is Blocked By STP

What could be the reason that port 4 is switching between port offline and getting blocked by STP?

3 REPLIES 3
Richard Litchfield
Respected Contributor

Re: Edge port continuously switching between Port-offline and blocked by STP

Are both ports on the phone 1Gb? Does the PC plug directly into the switch port without the phone in-line?

Check the logs (show logging -r) to see if anything else is going on.

If you are brave,  you could enable bpdu-filter on that port (spanning-tree <port> bpdu-filter) - but that may create major network problems elsewhere if there really is a spanning tree problem coming from the phone port. However, it seems more likely that STP is part of the symptom rather than the problem

Linkk
Frequent Advisor

Re: Edge port continuously switching between Port-offline and blocked by STP

Hi,

it is normal that a port is getting blocked by STP before it comes online. Please check the physical connection between the phone and the Switch, try different ports, try what happens if you connect the PC directly to the switch.


Is the phone powered via PoE and does it reboot/loose power? Are many devices powered by the switch? Does the problem still appear with the phone powered by an outside source?

parnassus
Honored Contributor

Re: Edge port continuously switching between Port-offline and blocked by STP

Cabling between that Switch port and that IP Phone port (and, to be sure, including the cabling between that IP Phone and the host it has connected via its mini Switch) should be verified (starting with the assumption that that whole cabling run, patches included, is/was Cat.5E/Cat.6 properly certified).

Once physical layer issues can be excluded a check of Port Status (configuration) done on both sides would be benefical (Speed negotiation and Mode Half/Full Duplex), that's to avoid mismatches between the involved Ethernet ports.

PoE (if deployed) could be the culprit but a general check (physical -> logical) would help too.

Also a check about Switch Firmware and IP Phone Firmware should not be excluded (some issues can be related to Firmware bugs, on both sides).