Quanta Cloud Technology QuantaMesh QNOS5, Configuration Manual

Page: 234 / 256

234
3. Enable PFC and configure traffic marked with 802.1p priority 5 to be paused rather than dropped when
congestion occurs.
(QCT) (Interface 0/3,0/5,0/10)#data-center-bridging
(QCT) (Config-if-dcb)#priority-flow-control mode on
(QCT) (Config-if-dcb)#priority-flow-control priority 5 no-drop
(QCT) (config-if-dcb)#exit
4. Enable VLAN tagging on the ports so the 802.1p priority is identified.
(QCT) (Interface 0/3,0/5,0/10)#switchport allowed vlan add tagged 100
(QCT) (Interface 0/3,0/5,0/10)#exit
9.3. Data Center Bridging Exchange Protocol
The Data Center Bridging Exchange Protocol (DCBX) is used by DCB devices to exchange configuration
information with directly connected peers. DCBX uses type-length-value (TLV) information elements over
LLDP to exchange information, so LLDP must be enabled on the port to enable the information exchange. By
default, LLDP is enabled on all ports. For more information, see “LLDP and LLDP-MED”.
The main objective of DCBX is to perform the following operations:

Discovery of DCB capability in a peer : DCBX is used to learn about the capabilities of the peer
device. It is a means to determine if the peer device supports a particular feature such as PFC.

DCB feature misconfiguration detection : DCBX can be used to detect misconfiguration of a
feature between the peers on a link. Misconfiguration detection is feature-specific because
some features may allow asymmetric configuration.

Peer configuration of DCB features : DCBX can be used by a device to perform configuration
of DCB features in its peer device if the peer device is willing to accept configuration.
DCBX is expected to be deployed in Fibre Channel over Ethernet (FCoE) topologies in support of lossless
operation for FCoE traffic. In these scenarios, all network elements are DCBX enabled. In other words, DCBX
is enabled end-to-end.
The DCBX protocol supports the propagation of configuration information for the following features:

Enhanced Transmission Selection (ETS)

Priority-based Flow Control (PFC)

Application Priorities
These features use DCBX to send and receive device configuration and capability information to the peer DCBX
device.
The Application Priorities information is simply captured from the peer and potentially propagated to other
peers by the DCBX component.
9.3.1. Interoperability with IEEE DCBX