Which technology uses LLDP TLVs to tell connected devices information such as the correct queue for PFC?

Data Center Bridging Capability Exchange (DCBx) is the correct technology. It is an extension of the Link Layer Discovery Protocol (LLDP) that uses specific Type-Length-Value (TLV) fields to communicate and negotiate Data Center Bridging (DCB) parameters between network switches and adapters. This exchange ensures that both ends of a link have a consistent configuration for features like Priority-based Flow Control (PFC), including which traffic classes (queues) are designated as no-drop, and Enhanced Transmission Selection (ETS) for bandwidth management.

A. ETS (Enhanced Transmission Selection) is a DCB feature for allocating bandwidth to traffic classes; it is configured and advertised using DCBx, but it is not the protocol itself.
B. PFC (Priority-based Flow Control) is a DCB mechanism for creating lossless Ethernet for specific priorities; it is also configured and advertised using DCBx.
C. ECN (Explicit Congestion Notification) is a congestion management mechanism, typically operating at Layer 3/4, and is not the protocol that uses LLDP TLVs for DCB configuration.

1. HPE ArubaOS-CX 10.11 Fundamentals Guide

Chapter: "Data Center Bridging (DCB)"

Page 2. "Data Center Bridging Exchange (DCBx) is an extension of Link Layer Discovery Protocol (LLDP) that enables configuration of DCB devices. DCBx allows switches and adapters to exchange information about their DCB capabilities and the operational configuration of those capabilities. DCBx is used to ensure a consistent configuration of DCB features across the network."

2. IEEE Std 802.1Qaz-2011

"IEEE Standard for Local and metropolitan area networks—Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks—Amendment 18: Data Center Bridging

" Clause 1

Page 1. This standard formally defines DCBx and specifies the LLDP TLVs used for exchanging parameters for PFC

ETS

and application priorities.

3. Stanford University

CS244: Advanced Topics in Networking

Lecture 11: Data Center Networking

Slide 38. Course materials describe Data Center Bridging (DCB) and note that "DCBX (DCB Exchange Protocol) is a discovery and capability exchange protocol... based on LLDP" used to configure features like PFC and ETS.