I have the following network setup:
4 Hosts (Debian, Ubuntu, 2x Freebsd) on a Gbit-Ethernet switch uplinked to ->
a 24-port Fast-Ethernet with a variety of heterogenous hosts in a local lan.
All of the hosts are in the same class C network and use the same gateway and dns server.
I recently added an Esxi server with 2 gbit-Ethernet cards to the network, with one card configured as a dedicated management interface, connected to the Fast-Ethernet switch with an IP in the local network. The other card, used by the VM-nets, is connected to the Gbit Ethernet switch. (I have also tried it the other way around)
The problem: the management network is intermittently unreachable from all but ONE machine, a FreeBSD machine on the same switch. Really weird. I can log into to any other host on the same switch and sometimes have a good connection, sometimes a "no route to host" when I try to ping the management interface. But the connection from the one FreeBSD box on the same switch is rock stable.
I have, of course, tried replacing cables and every possible switch <-> host combination.
Any ideas on what is going on or how to troubleshoot this?