Link bonding / aggregation can be used to bond two ethernet adapters together so they act as one increasing performance and reliability (if one of the links go down the other might still work). Our switch can do some form of bonding of its ports (called link aggregation) and Gentoo supports link bonding (see HOWTO Setup Bonded Ethernet Adapters). Also relevant is Ethernet bridging.
We should look into this because it can potentially increase the network speed from 1 Gbit to 2 Gbit. Only do this if the bottle neck is the network connection.