Users Guide

Data Center Bridging Features 1133
Interoperability with IEEE DCBx
To be interoperable with legacy industry implementations of the DCBx
protocol, The Dell EMC Networking N4000 Series switches use a hybrid
model to support both the IEEE version of DCBx (IEEE 802.1Qaz) and
legacy DCBx versions.
The Dell EMC Networking N4000 Series 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). DCBx can also be
configured 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
Ports operating in the manual role do not have their configuration affected by
peer devices or by internal propagation of configuration. These ports have
their operational mode, traffic classes, and bandwidth information specified