So I've got this really bizarre problem so please bear with me as I explain.... Previous environment: 4 buildings with multiple B5-series switches/stacks. I stack in each building is/was the MDF connected by 10G GBIC fiber to a K6 core. All remaining B5 switches/stacks is/were IDF connected to MDF by copper.
Recently we deployed fiber runs in all buildings. In 3 buildings we connected the IDF switches/stacks to the MDF using 1G GBICs. Those buildings went well and work fine.
In one building, in addition to adding fiber between the MDF & IDFs, we deployed x450G2 switches in the MDF and 4 of 6 IDFs, and the old B5 switches/stacks are now connected to the new x450G2’s using copper. the 4 x450 IDFs are connected by 10G GBICs and the 2 remaining B5 switches are connected to the x450s using copper. The transition to x450’s and fiber connections has gone well except for one snag….
One of those B5s currently connected by copper needs to also transition to fiber connecting to the x450 MDF. We are attempting to use 1G GBICs on both the B5 and the x450 MDF. If I plug everything in the fiber appears to work fine. Good uplink lights - good replies - I can connect to the B5.
…and here comes the mind-blowing part….
When I disconnect the old copper uplink to the x450 MDF I lose connectivity to any and all other B5’s from the network, and any devices connected to them appear to lose any network connectivity. This is also effectively happening when I plug the GBIC into the B5 fiber port of the same number, thus disabling the old copper uplink port. Either way, all other B5’s go down (no connectivity). Even if I remove all GBICs/fiber from this leg entirely, I still lose all the other B5’s when I pull (temporarily) the copper uplink. So the fiber/GBICs appear to have nothing to do with the problem.
I’m new to EXOS but as best as I can tell there is no ELRP configured. It’s disabled per default. The uplink ports on the B5 do not have Spanguard enabled. This B5 only has 2 ports in use - the uplink to the MDF and another small B5 “downstream”.
I’ve also cleared arp/iparp on all switches. The x450's each only have 1 route set up on the management VLAN (not the built-in management VLAN/4095) pointing to the VLAN interface on our K6 core.
Why can't I remove/disconnect a B5 that's physically out on it's own leg of the network? I’m clueless - please help!