I have a network with a core stack of 3 Dell 6248 switches. These are connected via stacking cables and are configured as a stack.
I have a 4th 6248 switch in a wiring closet that connects to the main stack via 10G base-T copper Ethernet cables. These 10G Base-T cables connect to two different switches in the stack. I've attached a diagram of the network switch layout. All switches are running the latest software 3.3.7.3.
Here's a config snip showing how the 10G ports are configured on the stack:
interface ethernet 1/xg3
channel-group 1 mode auto
exit
!
interface ethernet 2/xg3
channel-group 1 mode auto
exit
!
I have a similar channel-group configured on the closet switch. All my VLANs are trunked over this channel group.
I have no layer 3 routing configured on the switches, and no spanning tree.
All is working perfectly..... Until...
Earlier today the closet switch stopped passing traffic, and some traffic within the core switch also was dropping.
After some troubleshooting, the problem was narrowed down to one Mac workstation (of course it was a Mac!) This Mac was so jacked up we ended up wiping it and starting over. But whenever it was plugged into the network, it would immediately cause all traffic on the switch to stop. It also trashed all traffic on all VLANs on the closet switch - not just the VLAN this Mac was assigned.
It seemed to me like a network loop, although this was just a single computer plugged into the network with a single port.
Questions:
1. How can one computer completely trash a network?
1a. Does it seem odd that other VLANs were effected?
2. Would spanning tree have helped in this situation?
2a. Should I turn spanning tree on?
2b. What problems might I see if I do enable spanning tree?
3. Any theories as to why was some of the traffic on the core switch was effected?
3a. Is it possible that some of the traffic between the core switches traversing over the 10G connection instead of the stack?
4. Is my network design acceptable?
4a. Is there a better way for me to connect a closet switch to the Core?
Any other insights or comments are appreciated.
Thanks!!