Administrator 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 devices but do not accept
272 Data Center Bridging (DCB)