Users Guide
– No other port is the conguration source.
– The port role is auto-upstream.
– 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 conguration values through either a symmetric or asymmetric parameter
exchange.
A newly elected conguration source propagates conguration changes received from a peer to the other auto-conguration ports. Ports
receiving auto-conguration information from the conguration source ignore their current settings and use the conguration source
information.
Propagation of DCB Information
When an auto-upstream or auto-downstream port receives a DCB conguration from a peer, the port acts as a DCBx client and checks if a
DCBx conguration source exists on the switch.
• If a conguration source is found, the received conguration is checked against the currently congured values that are internally
propagated by the conguration source. If the local conguration is compatible with the received conguration, the port is enabled for
DCBx operation and synchronization.
• If the conguration received from the peer is not compatible with the internally propagated conguration used by the conguration
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 conguration is later received from the peer, the port is
enabled for DCBx operation.
NOTE
: DCB congurations internally propagated from a conguration source do not overwrite the conguration on a DCBx port
in a manual role. When a conguration source is elected, all auto-upstream ports other than the conguration source are marked
as
willing disabled
. The internally propagated DCB conguration is refreshed on all auto-conguration ports and each port may
begin conguration negotiation with a DCBx peer again.
Auto-Detection and Manual Conguration 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 recongures 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-congured CLI commands require the version negotiation to restart.
• The peer times out.
• Multiple peers are detected on the link.
If you congure a DCBx port to operate with a specic version (the DCBx version {cee | cin | ieee-v2.5} command in the
Conguring DCBx), DCBx operations are performed according to the congured version, including fast and slow transmit timers and
message formats. If a DCBx frame with a dierent 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 eort, it is possible that CIN frames may be processed when DCBx is congured 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 dened to maintain the sequence number and acknowledge
the number sent in the DCBx control TLVs.
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Data Center Bridging (DCB)