I have not had a tremendous amount of exposure to Layer 2 Networking in Linux, or in general.
The SD-WAN product at my previous startup company has a Layer 2 Gateway that essentially would allow corporations to join LAN segments over a wide area network. So people sitting in an office in, say, Seattle, could be "theoretically" sitting next to some colleagues sitting in an office in, say, Atlanta. All on the same LAN segment. How the product did this is a separate discussions since it involved taking Ethernet Frames, and transporting / tunneling them across the internet (albeit in a very creative and very fast way due to link aggregation, UDP acceleration, multiple channels for delivering the tunneled packets, et al).
I only scratched the surface in terms of understanding the nuances of L2 with this. For example, I learned quite a bit about Bridging (from a Linux perspective). I learned a bit about Spanning Tree Protocol as well, and BPDUS.
I had heard about protocols like LLDP (Link Layer Discovery Protocol), and LACP (Link Aggregation Control Protocol), but since I was not dealing with commercial switches and things, I had no need for enabling, configuring, tuning or analyzing these protocols.
But - I am in an environment now, where these things start to matter a bit more. We run OpenStack hosts that connect to large Juniper switches. These Linux servers are using Link Aggregation and Bonding, and as such, are configured to use LACP to send PDUs to the switches.
LLDP is also enabled. With LLDP, devices advertise their information to directly-connected peers/neighbors. I found a good link that describes how to enable LLDP on Linux.
https://community.mellanox.com/s/article/howto-enable-lldp-on-linux-servers-for-link-discovery
This Juniper document does a pretty good job of discussing LACP.
Understanding LAG and LACP
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