Administrator Guide

DCBx Operation
DCBx performs the following operations:
• Discovers DCB conguration (such as PFC and ETS) in a peer device.
• Detects DCB mis-conguration in a peer device; that is, when DCB features are not compatibly congured on a peer device and
the local switch. Mis-conguration detection is feature-specic because some DCB features support asymmetric conguration.
• Recongures a peer device with the DCB conguration from its conguration source if the peer device is willing to accept
conguration.
• Accepts the DCB conguration from a peer if a DCBx port is in “willing” mode to accept a peer’s DCB settings and then internally
propagates the received DCB conguration to its peer ports.
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.
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FC Flex IO Modules