Deployment 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 receives its conguration from DCBX peers (ToR or
FCF device). 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.
252 Data Center Bridging (DCB)