Configuring Data Center Bridging Features 993
Interoperability with IEEE DCBx
To be interoperable with legacy industry implementations of the DCBx
protocol, The Dell Networking N4000 switches use a hybrid model to support
both the IEEE version of DCBx (IEEE 802.1Qaz) and legacy DCBx versions.
The N4000 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
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