Lenovo Flex System Fabric CN4093, Application Manual

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CN4093 Application Guide for N/OS 8.4
Data Center Bridging Capability Exchange
Data Center Bridging Capability Exchange (DCBX) protocol is a vital element of
CEE. DCBX allows peer CEE devices to exchange information about their
advanced capabilities. Using DCBX, neighboring network devices discover their
peers, negotiate peer configurations, and detect misconfigurations.
DCBX provides two main functions on the CN4093:
 Peer information exchange
The switch uses DCBX to exchange information with connected CEE devices.
For normal operation of any FCoE implementation on the CN4093, DCBX must
remain enabled on all ports participating in FCoE.
 Peer configuration negotiation
DCBX also allows CEE devices to negotiate with each other for the purpose of
automatically configuring advanced CEE features such as PFC, ETS, and (for
some CNAs) FIP. The administrator can determine which CEE feature settings
on the switch are communicated to and matched by CEE neighbors, and also
which CEE feature settings on the switch may be configured by neighbor
requirements.
The DCBX feature requires CEE to be turned on (see “Turning CEE On or Off” on
page 302 ).
DCBX Settings
When CEE is turned on, DCBX is enabled for peer information exchange on all
ports. For configuration negotiation, the following default settings are configured:
 Application Protocol: FCoE and FIP snooping is set for traffic with 802.1p
priority 3
 PFC: Enabled on 802.1p priority 3
 ETS

Priority group 0 includes priority values 0 through 2, with bandwidth
allocation of 10%

Priority group 1 includes priority value 3, with bandwidth allocation of 50%

Priority group 2 includes priority values 4 through 7, with bandwidth
allocation of 40%