Configuring Data Center Bridging Features 819
DCBX information is carried over LLDP, which is a link-local protocol. When 
configuring links in a port channel to use DCBX, the DCBX settings should 
be the same for all links in the port channel.
Interoperability with IEEE DCBx
To be interoperable with legacy industry implementations of the DCBx 
protocol, The PowerConnect 8024/8024F/81xx switches use a hybrid model 
to support both the IEEE version of DCBx (IEEE 802.1Qaz) and legacy 
DCBx versions. 
The PowerConnect 8024/8024F/81xx switch automatically detects whether a 
peer is operating with either of the two CEE DCBx versions or the IEEE 
standard DCBx version (the default mode). You can also configure DCBx to 
manually select one of the legacy versions or IEEE standard mode. In auto-
detect mode, the switch starts operating in IEEE DCBx mode on a port, and 
if it detects a legacy DCBx device based on the OUI of the organization TLV, 
then the switch changes its DCBx mode on that port to support the version 
detected. There is no timeout mechanism to move back to IEEE mode. If the 
DCBx peer times out, multiple peers are detected, the link is reset (link 
down/up) or if commanded by the operator, DCBx resets its operational mode 
to IEEE.
The interaction between the DCBx component and other components 
remains the same irrespective of the operational mode it is executing. For 
instance, the DCBx component interacts with PFC to get needed 
information to pack the TLVs to be sent out on the interface. Based on the 
operational control mode of the port, DCBx packs it in the proper frame 
format.
DCBx and Port Roles
The behavior of each port is dependent on its operational mode and that of 
other ports in the stack. The port mode is a DCBx configuration item that is 
passed to the DCBx clients to control the processing of their configuration 
information. There are four port roles:
1
Manual
2
Auto-Upstream
3
Auto-Downstream
4
Configuration Source