DCB Protocol

DCB is a term commonly used to describe Ethernet enhancements to improve Ethernet networking and management in data center environments. DCB is a framework that defines the enhancements that are required for switches and endpoints and includes the following features:

• ETS is the enhanced transmission selection specification, which provides bandwidth management as well as a scheduling algorithm for various traffic classes on a converged link.

• PFC is an enhancement to the existing Ethernet pause protocol. This feature allows "no-drop" packet delivery for certain traffic classes.

This release of the SEFOS DCB feature supports both IEEE DCBX and DCB version 1.0.1, as specified by the DCB task group. By default, DCB version 1.0.1 (CEE) is chosen. Only one version of DCB protocol can be configured at one time.

DCB features are discovered and exchanged using the DCBX protocol. DCBX uses LLDP to exchange parameters between two converged link peers. The parameters that are exchanged by DCB are packaged into organizationally specific TLVs and sent to the peer through LLDP messages.

The OUI used for the IEEE DCBX TLV is 0x001B21. Because DCBX is an acknowledged protocol that uses LLDP, both transmit and receive directions from LLDP must be enabled on the interface that runs DCBX.

In addition to exchanging DCB parameters with the link partner, the local system DCBX entity works closely with the QoS module to configure the scheduling policy, manage bandwidth, and control the priority flow control in the hardware.