Auto-Detection Of The Dcbx Version; Dcbx Example - Dell PowerEdge M IO Aggregator Command Reference Manual

Auto-Detection of the DCBX Version

The Aggregator operates in auto-detection mode so that 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).
• The peer times out.
• Multiple peers are detected on the link.
DCBX operations on a port are performed according to the auto-configured DCBX 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.

DCBX Example

Figure 6-7 shows how DCBX is used on an Aggregator installed in a PowerEdge M1000e chassis in which
servers are also installed.
• The external 40GbE ports on the base module (ports 33 and 37) of two switches are used for uplinks
configured as DCBX auto-upstream ports. The Aggregator is connected to third-party, top-of-rack
(ToR) switches through 40GbE uplinks. The ToR switches are part of a Fibre Channel storage
network.
• The internal ports (ports 1-32) connected to the 10GbE backplane are configured as auto-downstream
ports.
• On the Aggregator, PFC and ETS use DCBX to exchange link-level configuration with DCBX peer
devices.
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