Why can I add two network devices to a bridge?

[joscu]

Hey! im trying to learn about ethernet node proxmox (and learning english...) and i dont understand two things.

First, why is possible to add two network devices to a bridge, if we can use bond.

And the last, why can i put IP to a bridge, if i put IP to the Virtual machine?

Thanks!!

 

[joscu]

 

[B.Otto]

Hello,

a bridge is something like a switch. If you add two NICs to a bridge, you can make two different connected network devices talk to eachother via the bridge.

A bond combines several NICs to for one big 'virtual' network device. Depending on how the bond is set up that can increase the bandwidth and/or add redundancy.

If you are not bonding your interfaces do NOT add several interfaces to one nic and connect them to the same switch, as this will cause a network loop.

The IP on the bridge is an IP address that your Proxmox host holds. So through this IP you can connect to your Proxmox host. In that way you can both connect to your Proxmox host and to your virtual machines through the same interface. (if your VMs have a virtual network card attached to this bridge)

Kind regards,
Benedikt

 

[joscu]

First of all thanks for answering.

If you are not bonding your interfaces do NOT add several interfaces to one nic and connect them to the same switch, as this will cause a network loop.

Are you saying this because of the image I posted? because both are enp0sX? its like this because its a virtual machine.
I think that i understood your explanation. Bridge can use two or more interfaces to be able to communicate with each other, as if we were connecting two network cards to the same switch

Thanks!!

 

[B.Otto]

Are you saying this because of the image I posted? because both are enp0sX? its like this because its a virtual machine.

Yeah, I wrote this because it is quite rare that you would want to add several physical interfaces to a single bridge.

The basic way is one physical interface to the bridge:

• Bridge vmbr0
  • Bridge ports: enp0s0

If you want to use bonding, you make a bond bond0 with your interfaces and then add that single virtual interface bond0 to the virtual bridge

• Bond bond0
  • Port Slaves: enp0s0, enp0s1
• Bridge vmbr0
  • Bridge ports: bond0

In both cases the bridge holds only one interface.

Kind regards,
Benedikt