How to check network loops on a core switch
You can test/check for network loops without disabling any ports by using Loop-Protect and setting the Receiver-Action to "no-disable". If one is detected, it will add an entry to the event log, but will not disable the port. A network loop occurs when redundant connections between switches cause data packets to endlessly circulate, suitable to broadcast storms, high CPU usage, and network congestion. Now at most of our sites we use Extreme, which has a handy feature called ELRP Extreme Loop Recovery Protocol, despite the name, this mechanism just detects loops, in the logs we can see, ok. The problem happening is that the core switch is disabling one uplink configured as a lag to one of the edge cabinets, when viewing the logs on the core, i found the below : LOOP DETECTION: VLAN 102, port lg110 detect, putting into err-disable state after disabling, reenabling the lag ports on the. There is also of course the way to get a hard proof by using Wireshark and a packet capture to check if one and the same frame is appearing with a.
Read More
