Link aggregation is a widespread mechanism in networks. The linux kernel bond driver currently supports 7 different modes. However, Source Load Balancing (balance-slb) is only supported by OpenvSwitch. SLB bonding allows load balancing without remote switch's knowledge or cooperation. SLB assigns each source MAC+VLAN pair to a link and transmits all packets from that MAC+VLAN through that link. Now this is also available on kernelspace by a combination of nftables rules and kernel bonding configuration, all automated through NetworkManager balance-slb option.

On this talk, we will explore how SLB balancing works and how it was implemented by using nftables and kernel bond driver. In addition, we will explore scenarios where this is useful and some known problems.