In the report system, there is a report titled "Direct neighborship candidates". Can you find any candidate neighbors for port X there?
No.
There is an idea, that hasn't been implemented, that the topology detector should remove topology information for a port that is down, if the old neighboring port is still up - which would be an indicator of your case, where the link has been taken away and one of the ports reused for another link.
Ok, what if the 'clear the alerts' action removed the link from the topology? Acknowledge the alert would indicate that the link-down is temporary.
OTOH, we know of several weaknesses in the topology detector come from simply using the same topology deduction algorithm for LLDP and CDP data as is used for CAM-based data. We are working on a rewrite of the topology detector to use more reasonable algorithms with data provided from LLDP and CDP [1], which should hit NAV 4.8 sometime this fall.
Looking forward to it :).
Thanks for the clarifications.
best regards Andreas Dobloug USIT/UiO