Networking not working for KVM guests

[Alexqw]

Hey everyone,
First, I would like to say that Proxmox is a great piece of software. It's been very easy to use and provides a lot of great flexibility.
Recently I physically moved my proxmox server to a datacenter. Prior to the move only one NIC was used. After the move I created a bond interface for two NICs using balance-rr. The network comes up just fine. It works for the physical server and all OpenVZ guests (which all are using venet). However, the KVM guests cannot access the network. IPs are set and I have confirmed all network information is correct in the guest. I cannot even ping my gateway. The network card for the KVM guests are virtio and point to vmbr0. I have deleted the network card and recreated it, just in case that was the issue. No dice.
Am I missing a known problem with connecting KVM guests to a bridge device to a bond device?

---Alex

 

[Lokytech]

Maybe a problem with your switch ? What switch do you use ?

 

[Alexqw]

So I figured out the problem with this. This thread outlined a solution that worked for me. I do have to say that I don't understand the bridging options as much as I'd like to, but from what I understand turning STP on for the bridge interface is likely what fixed it.
If anyone is able to better describe what the following bridging options do, I would appreciate it.

bridge_stp on
bridge_maxwait 0
bridge_maxage 0
bridge_fd 0
bridge_ageing 0

---Alex