What multi-homed connectivity options are available?

Multi-homed / diverse transit delivery can be handled in a number of ways.

The most common approaches are:

Layer 2

Active/Active

This is where both ports are physically up, and both will pass traffic together. Your infrastructure must support LACP, which is usually found in a LAG/port-channel/ether-channel (naming dependent on hardware vendor) i.e. a logically stacked switch pair, router with LAG capability, a single managed switch etc.

Active/Passive

This is where both ports are physically up, but only one will pass traffic at any one time. Your infrastructure doesn't need to support LACP i.e. a dumb switch, or a pair of devices that are not logically stacked. For a failover to occur the currently active port needs to go down (i.e. a cable is unplugged, a port shut, or our infra is taken offline due to failure or maintenance).

Layer 3 / BGP

A BGP session is required for each access port to enable multi-homed Layer 3 hand-off. You can then configure high-availability on your own device(s) as appropriate.