Running multiple services across multiple machines and implementing appropriate HA methods ensure a high degree of tolerance to failure within our environment, but if it's the physical network that fails and not the service, outages will occur if traffic cannot flow to and from that service. Adding in NIC bonding (also known as teaming or link aggregation) can help alleviate these issues by ensuring traffic flows through diverse routes and switches as appropriate.
NIC bonding requires co-ordination between system administrators and the network administrators, who are responsible for the switches. There are various methods available for NIC bonding. The method presented here is active-passive mode, which describes that traffic will normally flow through a single switch, leaving the other teamed NIC to take no traffic until it is required.