Command Line Interface Guide

844 Data Center Bridging Commands
the port. The expectation is that the network administrator configures the
upstream devices appropriately so that all such devices advertise a
compatible configuration.
Auto-Downstream
Advertises a configuration but is not willing to accept one from the link
partner. However, the port will accept a configuration propagated internally
by the configuration source. Specifically, the willing parameter is disabled on
auto-downstream. By default, auto-downstream ports have the
recommendation TLV parameter enabled. Auto-downstream ports that
receive internally propagated information ignore their local configuration and
utilize the internally propagated information.
Configuration Source
In this role, the port has been manually selected to be the configuration
source. Configuration received over this port is propagated to the other auto-
configuration ports, however, no automatic election of a new configuration
source port is allowed. Events that cause selection of a new configuration
source are ignored. The configuration received over the configuration source
port is maintained until cleared by the operator (set the port to the manual
role). FIP snooping must be enabled to set a port to configuration source.
Configuration Source Port Selection Process
When an auto-upstream or auto-downstream port receives a configuration
from a peer, the DCBX client first checks if there is an active configuration
source. If there is a configuration source already selected, the received
configuration is checked against the local port operational values as received
from the configuration source, and if compatible, the client marks the port as
operationally enabled. If the configuration received from the peer is
determined to not be compatible, a message is logged, an error counter is
incremented and the DCBX clients become operationally disabled on the
port. The port continues to keep link up and exchanges DCBX packets. If a
compatible configuration is later received, the DCBX clients will become
operationally enabled.
If there is no configuration source, a port may elect itself as the configuration
source on a first-come, first-serve basis from the set of eligible ports. A port is
eligible to become the configuration source if:
2CSPC4.XModular-SWUM201.book Page 844 Monday, October 3, 2011 2:21 PM