Propagation Of Dcb Information; Auto-Detection And Manual Configuration Of The Dcbx Version - Dell S4048–ON Configuration Manual

• The port is enabled with link up and DCBx enabled.
• The port has performed a DCBx exchange with a DCBx peer.
• The switch is capable of supporting the received DCB configuration values through either a symmetric or asymmetric parameter
exchange.
A newly elected configuration source propagates configuration changes received from a peer to the other auto-configuration ports. Ports
receiving auto-configuration information from the configuration source ignore their current settings and use the configuration source
information.

Propagation of DCB Information

When an auto-upstream or auto-downstream port receives a DCB configuration from a peer, the port acts as a DCBx client and checks if a
DCBx configuration source exists on the switch.
• If a configuration source is found, the received configuration is checked against the currently configured values that are internally
propagated by the configuration source. If the local configuration is compatible with the received configuration, the port is enabled for
DCBx operation and synchronization.
• If the configuration received from the peer is not compatible with the internally propagated configuration used by the configuration
source, the port is disabled as a client for DCBx operation and synchronization and a syslog error message is generated. The port keeps
the peer link up and continues to exchange DCBx packets. If a compatible configuration is later received from the peer, the port is
enabled for DCBx operation.
NOTE: DCB configurations internally propagated from a configuration source do not overwrite the configuration on a DCBx port
in a manual role. When a configuration source is elected, all auto-upstream ports other than the configuration source are marked
willing disabled . The internally propagated DCB configuration is refreshed on all auto-configuration ports and each port may
as
begin configuration negotiation with a DCBx peer again.

Auto-Detection and Manual Configuration of the DCBx Version

When operating in Auto-Detection mode (the DCBx version auto command), a DCBx port automatically detects the DCBx version on
a peer port. Legacy CIN and CEE versions are supported in addition to the standard IEEE version 2.5 DCBx.
A DCBx port detects a peer version after receiving a valid frame for that version. The local DCBx port reconfigures to operate with the peer
version and maintains the peer version on the link until one of the following conditions occurs:
• The switch reboots.
• The link is reset (goes down and up).
• User-configured CLI commands require the version negotiation to restart.
• The peer times out.
• Multiple peers are detected on the link.
If you configure a DCBx port to operate with a specific version (the DCBx version {cee | cin | ieee-v2.5} command in the
Configuring DCBx), DCBx operations are performed according to the configured version, including fast and slow transmit timers and
message formats. If a DCBx frame with a different version is received, a syslog message is generated and the peer version is recorded in
the peer status table. If the frame cannot be processed, it is discarded and the discard counter is incremented.
NOTE: Because DCBx TLV processing is best effort, it is possible that CIN frames may be processed when DCBx is configured to
operate in CEE mode and vice versa. In this case, the unrecognized TLVs cause the unrecognized TLV counter to increment, but
the frame is processed and is not discarded.
Legacy DCBx (CIN and CEE) supports the DCBx control state machine that is defined to maintain the sequence number and acknowledge
the number sent in the DCBx control TLVs.
274 Data Center Bridging (DCB)