What is the default CoS value for FCoE packets on a storage VDC?

CoS 1 is typically used for background or best-effort traffic and is not the default for FCoE.

CoS 2 is often used for operations, administration, and management (OAM) traffic, not for FCoE.

On Cisco Nexus platforms, the default Class of Service (CoS) value assigned to Fibre Channel over Ethernet (FCoE) packets is 3. This CoS value is part of the FCoE priority tagging mechanism, which is critical for ensuring lossless transport of Fibre Channel traffic over an Ethernet network.

CoS 5 is commonly assigned to video conferencing or voice signaling traffic, not for FCoE.

CoS 7 is generally reserved for network control traffic, which is the highest priority, and not the default for FCoE.