Bitcoin Forum

I think one my network switches may be going bad.

A description of my setup might help.  Got a workstation PC (Windows 7, remote desktop) in my office.  Cable modem & Router are there also. 

I have a drop from router going to the garage where I have an 8 port switch and my five other rigs mining away.  I noticed last night one of my rigs went offline.  I wouldn't remote into it but using KVM over IP I can access it just fine.  cgminer wasn't locked it just wasn't connecting to internet.  Even ping of the rig went nowhere.   I didn't want to waste anytime so I rebooted the rig but that didn't fix it.

I tried a lot of things but couldn't get the rig online (or access the rig via SSH) but could access the rig from KVM over IP.  Long story short I tried using the other network port (only had 1 connected) and it came online and began hashing right away.  Didn't have any time to mess with it further.

Today (I am checking on them remotely) 3 of the other rigs went offline.  GRR.  Even weirder I can't SSH into them from my workstation but I can access them via KVM.  Even more weird is I SSHed into one of the online rigs and used SSH from that rig into one of the down rigs and that works.  Both the "good" rig and "down" rig are on the same switch.

Only thing I can think of is somehow the MAC lookup table in the switch or router is getting hosed (technical term).  Really annoying I am going to lose 5+ hours on 7GH.  >:(

Most common problem I see with switches is that they go crazy when the MAC address of some card is all zeros. Check the "locally administered MAC address", "network address" (or equivalents) has "not present" checked in the device manager. It is really easy to accidentally click on the "Value" textbox without filling the valid value, thus you'll get a card with MAC address of all zeros.