Libro sobre Proxmox maestria
Chapter 5
Based on this configuration, the pmxvm01 node has two virtual bridges set up. Bridge vmbro is tied to physical network interface eth0, and bridge vmbrl is tied to eth1 of the node. If we want to create a fully isolated subnet without any outgoing traffic, we could edit bridge vmbrl to look like the following code:
auto vmbrl iface vmbrl inet manual bridge ports none bridge_stp off bridge_fd 0 bridge_stp
The bridge_stp option allows multiple bridges to communicate with each other for network discovery and loop avoidance. This is useful to eliminate data cycles to provide optimal packet routing, because with STP on, bridges can talk to each other and figure out how they are connected and then provide best routing possible for data packet transmission. STP also allows fault tolerance since it will check the network topology if a bridge fails. To turn on the STP option, just modify the bridge configuration as follows:
bridge_stp on STP increases bandwidth efficiency while posing security issues. Do not use STP when a virtual subnet requires isolation from other virtual subnets in the same cluster, and you do not want the bridges to talk to each other. It is a useful option when working in a virtual environment of the same company where data can flow freely between department subnets. STP does not have any authentication and assumes all network interfaces to be trustworthy. When a hostile bridge enquires about the network topology from another bridge, information is freely shared without any authentication. Thus, a user in the hostile bridge could potentially gather data of the entire network topology and other bridges in the network. This leads to a dangerous situation with bridging between the internal environment and the Internet. STP is turned off by default.
FD refers to Forwarding Delay. The bridge_fd option sets the delay of how long before the interface will be ready. During the delay, bridge tries to discover other bridges and checks there are no network loops if STP is on. By default, the forwarding delay is set to 0 as shown in the following line of code:
bridge_fd 0