Users Guide

DCBx Port Roles
To enable the auto-conguration of DCBx-enabled ports and propagate DCB congurations learned from peer DCBx devices
internally to other switch ports, use the following DCBx port roles.
Auto-upstream The port advertises its own conguration to DCBx peers and is willing to receive peer conguration. The
port also propagates its conguration to other ports on the switch.
The rst auto-upstream that is capable of receiving a peer conguration is elected as the conguration
source. The elected conguration source then internally propagates the conguration to other auto-
upstream and auto-downstream ports. A port that receives an internally propagated conguration
overwrites its local conguration with the new parameter values. When an auto-upstream port (besides the
conguration source) receives and overwrites its conguration with internally propagated information, one of
the following actions is taken:
• If the peer conguration received is compatible with the internally propagated port conguration, the link
with the DCBx peer is enabled.
• If the received peer conguration is not compatible with the currently congured port conguration, the
link with the DCBx peer port is disabled and a syslog message for an incompatible conguration is
generated. The network administrator must then recongure the peer device so that it advertises a
compatible DCB conguration.
– The conguration received from a DCBx peer or from an internally propagated conguration is not
stored in the switch’s running conguration.
– On a DCBx port in an auto-upstream role, the PFC and application priority TLVs are enabled. ETS
recommend TLVs are disabled and ETS conguration TLVs are enabled.
Auto-downstream The port advertises its own conguration to DCBx peers but is not willing to receive remote peer
conguration. The port always accepts internally propagated congurations from a conguration source. An
auto-downstream port that receives an internally propagated conguration overwrites its local conguration
with the new parameter values.
When an auto-downstream port receives and overwrites its conguration with internally propagated
information, one of the following actions is taken:
• If the peer conguration received is compatible with the internally propagated port conguration, the link
with the DCBx peer is enabled.
• If the received peer conguration is not compatible with the currently congured port conguration, the
link with the DCBx peer port is disabled and a syslog message for an incompatible conguration is
generated. The network administrator must then recongure the peer device so that it advertises a
compatible DCB conguration.
– The internally propagated conguration is not stored in the switch's running conguration.
– On a DCBx port in an auto-downstream role, all PFC, application priority, ETS recommend, and ETS
conguration TLVs are enabled.
Conguration source The port is congured to serve as a source of conguration information on the switch. Peer DCB
congurations received on the port are propagated to other DCBx auto-congured ports. If the peer
conguration is compatible with a port conguration, DCBx is enabled on the port.
On a conguration-source port, the link with a DCBx peer is enabled when the port receives a DCB
conguration that can be internally propagated to other auto-congured ports. The conguration received
from a DCBx peer is not stored in the switch’s running conguration. On a DCBx port that is the
conguration source, all PFC and application priority TLVs are enabled. ETS recommend TLVs are disabled
and ETS conguration TLVs are enabled.
Manual The port is congured to operate only with administrator-congured settings and does not auto-congure
with DCB settings received from a DCBx peer or from an internally propagated conguration from the
conguration source. If you enable DCBx, ports in Manual mode advertise their congurations to peer
Data Center Bridging (DCB)
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