@jolly-waitress-71272 So yes, this arrangement seemed to work fine. There's actually not much more to add. We installed 100Gb NICs in two servers and connected them with a direct attach copper cable. One of the servers then had an additional 10Gb NIC, connected to the switch to which other machines were connected. On the machine with the two NICs, we made sure the two new interfaces did not have IP addresses, created a bridge, added the two NICs to it, and assigned the bridge an IP address. The only thing that was unexpected was that we had to allow forwarding in iptables on the bridge interface (this was unexpected for us as the bridge machinery sits "below" IP in the stack).